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Splitting stars – for us and for you!

We are experienced amateur astronomers who especially enjoy viewing double stars with long-focus refractors.  This journal is a record of our observations, but we also hope it will serve as a guide to you to help you plan observing sessions and choose double stars you want to observe.  In the column to the left you’ll find a drop down menu listing the doubles in this blog by constellation – and to the right there’s a list of our 10 most recent observations. Finally, you have two other choices:

  • First, you can read  our observations of a double and leave your own observations of that same star as a comment.
  • Second, you can subscribe to this blog so that you get email notifications when we add a star to it. Just check out the links in the right-hand column.

We’d love to hear from you regarding your own observations of the same doubles.

Sub-Arc Second Successes: Bu 63 (β 63) and Lambda (λ) Cygni

Excerpted from Stelladoppie (http://stelledoppie.goaction.it/index2.php?menu=39&iddoppia=91210).

Lambda Cygni separation and PA from 2000 to 2030 based on orbital data. Click for a better view.

Like many other parts of our planet, it’s not often the skies above me are graced with sub-arc second seeing.   Over the course of a year, I can count the number of times that happens on one hand. Even more to the point, some of those one-handed opportunities only last for an hour or so — which means I’m always watching for subtle signs of advantageous alterations in atmospheric conditions. When those happen, if I don’t grab the ring while it’s being dangled in front of my telescope lens, I find myself resorting to a very un-astronomical like vocabulary when the seeing returns to its normal wretched state.

Many moons ago, Neil English pointed me toward Lambda (λ) Cygni, a fourth magnitude star that lives on the Swan’s eastern wing. There’s more than one component listed for Lambda (λ) Cyg in the WDS, but the one Neil alerted me to is located just under an arc second from the primary.   The Stelladoppie chart at the right, which incorporates data from the WDS Ephemerides table, shows the AB pair with a separation of .0915” as of January 1st, 2014, with an imperceptible widening to .0916” by January 1st, 2015. Add the 1.53 magnitudes of difference between the two stars (4.73 and 6.26) and the result is a difficult pair to part.

Lambda Cygni   (OΣ 413)  (S 765)         HIP: 102589   SAO: 70505
RA: 20h 47.4m   Dec: 36° 29’

Identifier   Magnitudes  Separation  Position Angle     WDS
MCA 63      Aa, Ab:   5.40,   5.80       0.052″         61.4°     2011
STT 413           AB:   4.73,   6.26       0.915″          0.6°     2014
S 765              AC:   4.76,   9.65     82.90″        106°     2012
FYM 126          AF:   4.76, 14.00     52.00″        119°     2012
Distance: 769 Light Years (Simbad)
Spectral Classification: “A” is B5, “C” is K2
Lambda (λ) and Delta (δ) Cygni are shown in light blue, click to enlarge the chart.

Lambda (λ) and Delta (δ) Cygni (mentioned further down in this post) are shown in midnight blue, click to enlarge the chart.

As is frequently the case in such cases, I failed on my first few attempts to crack the pair, but on the fourth (or fifth or sixth or seventh) try, I finally glimpsed the secondary hovering like a miniscule cracker crumb at the north edge of the primary.   I managed that success with a 9.25 inch Celestron Edge SCT, but later I parted the pair with my six inch f/10 refractor, and after that I matched Neil’s prowess with my five inch f/15 D&G refractor (he cracked the pair with his five inch f/12 Istar refractor).

Many, many, many moons later I found myself confronted with another difficult pair of almost attached stars while I was bush-whacking my way through Delphinus. Flamsteed graced the star with a “1”, as in 1 Delphini, but what made my hair stand on end and caused my curiosity quotient to quiver was its double star designation, Bu 63 (or β 63). I knew if the eagle-eyed Sherburne Wesley Burnham had been here, I was in for a visual tussle. And when I dug out the data, that’s precisely what I discovered:

Bu 63  (1 Delphini)       HIP: 101160   SAO: 106172
RA: 20h 30.30m   Dec: +10° 54’

Identifier   Magnitudes   Separation   Position Angle    WDS
Bu   63   AB:   6.20,   8.02        0.90″          350°    2009
Bu 297   AC:   6.20, 14.40      16.90″          340°    2006
Distance: 743 Light Years  (Simbad)
Spectral Classification: A1e
Bu 63 is located just under a degree southwest of Epsilon (ε) Delphini.  Click to enlarge the chart.

Bu 63 is located just under a degree southwest of Epsilon (ε) Delphini. Click to enlarge the chart.

Well aware I would be dancing with the difficult, I cranked up my courage and with a salute to the sky gods and a humble bow to the memory of the beloved S.W., I allowed myself to be lured to the edge of the proverbial stellar ledge, creeping forward carefully with my six inch f/10 on two separate nights of poor seeing. Each time I thought I could detect the secondary at the north edge of the primary, but the image refused to hold still for long enough to call it a solid sighting.

Several nights later I was roaming the skies with the 9.25 inch SCT in search of other targets, but Bu 63 was bouncing around in the back of my mind. After about an hour, I noticed fog was approaching from the southeast, so I thought I had better give Sherburne Wesley’s 63rd discovery another try before the fog obscured it, even though the seeing was a bit below average. I parked a 6mm AT Plössl (408x) in the scope’s diagonal, focused pain-stakingly-carefully, and very much to my astounded surprise, I could detect the secondary immediately, even though the image was hopping around badly. I had the impression the brighter sky background caused by the fog was actually providing some assistance.

The fog receded and stayed away for the next hour, granting me an unexpected wealth of time to study Bu 63.   The view in the short eye relief Plössl quickly annoyed my observing eye, so I replaced it with a 6mm TMB Planetary II with longer eye relief to appease my visual apparatus.  I also tried a 5mm UO Ortho (490x) and a 4mm TMB Planetary II (613x), but the seeing conditions refused to support the magnification levels.

So I settled in with the 6mm TMB PL II to watch an unsteady 408x show for about half an hour, and was pleasantly surprised by what I could see during interrupted intervals of frantic hopping. At times the image was almost un-focusable and at other times, for quark length fractions of a second, it was crystal clear – and provided I was paying rapt attention, it was quite easy to steal a glimpse of the secondary perched on the top edge of the diffraction ring.

During periods when the image was living somewhere between a focused and unfocused state, the secondary was just a bit more than a bright spot on the ring, but during the brief moments of crystal clear seeing, it appeared as a weak dot of white light just beyond the reach of the primary. During those moments the segment of the diffraction ring between the secondary and primary seemed to vanish from view, which was probably an illusion caused by the sudden sharpness of the image.  Given the erratic seeing conditions I had to wrestle with, I was amazed at the way the secondary revealed itself provided I sat still and waited patiently.

But still . . . . . . and yet . . . . . . . . . . and somehow . . . . . . . . . . . . I wanted something more substantial.   There was no doubt I was seeing the secondary, but what I really wanted was an image that would hold still for long enough to distinguish the secondary as an actual star, not as a nervous dot of specterous white light fading in and out of view. What I wanted was the equivalent of a sharply focused mental photograph.

** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **

Bu 63 haunted me for the next month.   Every time I was patrolling the skies with either my six inch f/10 or the 9.25 inch SCT, I put it under a high-powered eyepiece to see what would happen.   But the seeing was just never quite up to it, so I gave up and went on to other things.   Then one night in late August, I was checking the seeing by zeroing in on Delta (δ) Cygni, which always provides me with a good idea of what possibilities the night holds. It split easily, so I switched over to the east wing of Cygnus to look in on Lambda (λ) Cyg again, and once I found the right magnification . . . . . . . . . success was mine!

Pure unfiltered beauty! A sight that makes any visual observer’s pulse pulsate several pulses faster. The 9.65 magnitude “C” component can be see almost due east of the primary. (East & west reversed to match the SCT view, click on the sketch to make your heart race).

Pure unfiltered beauty! A sight that makes any visual observer’s pulse pulsate several pulses faster. The 9.65 magnitude “C” component can be seen almost due east of the primary. (East & west reversed to match the SCT view, click on the sketch to make your heart race).

And then a dancing image of Bu 63 and its twitching secondary rose like a Phoenix and draped itself over my view of Lambda (λ) Cyg.

Well, why not?  The two would make an interesting comparison.  Both have virtually the same separation between primary and secondary, but Bu 63 possesses a wider magnitude difference (1.82 for Bu 63, 1.53 for Delta Cyg) and fainter stellar magnitudes (6.20 and 8.02 for Bu 63, 4.73 and 6.26 for Delta Cyg).   I was getting badly ahead of myself, though.  Assuming Bu 63’s secondary would be there waiting for me was subject to one major danger:  we all know what happens when you assume.  So I switched quickly to pre-sume instead.

And it worked. I even got that sharp mental snapshot I had lusted after for over a month:

I really half expected to see “S.W. was here” carved on the side of the secondary, but maybe I just wasn’t using enough magnification. (East & west reversed again, click on the sketch to get the sharp mental snapshot effect).

I really half expected to see “S.W. was here” carved on the side of the secondary, but maybe I just wasn’t using enough magnification. (East & west reversed again, click on the sketch to get the sharp mental snapshot effect).

Click to enlarge the image.

Click to enlarge the image.

Of course, S.W. Burnham was here, as you can surmise from the two identifiers he left imprinted on 1 Delphini, Bu 63 and Bu 297. In fact, according to his notes (which are shown at the right), he discovered the secondary of Bu 63 with his six inch f/15 Clark refractor – he was, after all, the owner of a pair of eyes which would have been the envy of any eagle. You can see his first estimate of PA and separation there, dated 1874.70, followed quickly by another PA and separation dated 1874.92 (source). Those measures were made for Burnham by Baron Dembowski (identified by Δ, the Greek symbol for capital “D”), who provided the measures for Burnham’s discoveries during the years he was using the six inch refractor.

To get back to the comparison between our two stars, there was no doubt whatever about the prognostication of the data: Bu 63 was every bit more difficult as the numbers said it would be. I could actually detect Lambda Cyg’s secondary as a bump on the primary at 136x (18mm Radian) in the 9.25 inch SCT, which wasn’t quite the case for Bu 63, although I did see some indication of an irregularity at the correct spot on the primary’s edge. I didn’t need to increase the magnification all that much to pry Lambda “B” loose – a jump to 175x with a 14mm Radian was enough.

But Bu 63 was a few orders of magnitude (no pun intended) different. Because of their fainter magnitudes, the apparent diameter of the Bu 63 pair is smaller than that of the Lambda Cyg pair – not by a huge amount, but definitely enough to raise the level of difficulty, and definitely very obvious when you view the two stars back to back. The upshot is Bu 63’s secondary appears closer to the primary than Lambda Cygni’s, which is an optical illusion caused by the smaller apparent diameters of the stars.   The comparison below, which gets darn close to replicating the relative sizes and brightness levels of our two tight-knit pairs, provides a good indication of how much visual difference there is between the two stars.

Even though Bu 63 is under higher magnification, the apparent diameters of its two components is noticeably smaller than those of Lambda Cygni. Be prepared to experience genuine eye strain.

Even though Bu 63 is under higher magnification, the apparent diameters of its two components is noticeably smaller than those of Lambda Cygni. Be prepared to experience genuine eye strain.  Click for a slightly better view.

So give this a try some night when both stars are well placed in the sky and the atmosphere over your head is in an agreeable mood.   I highly recommend starting with Delta Cygni first to test the seeing, and then going on to Lambda Cygni if conditions warrant.  If you don’t succeed with Delta Cygni, it may be time to go hunting for galaxies instead . . . . . or to go find a good book.

Clear Skies!   :cool:

West of Sheliak (Beta Lyrae): Σ 2349, Σ 2333, and OΣΣ 172

This is a continuation of a two part tour in southwestern Lyra, the first part of which looked at an area south and southwest of Sheliak (you can get to it by clicking on this link if you missed it). This time we’re going to strike out west of Sheliak and see what gems were found in the celestial darkness by F.G.W. Struve and his son, Otto.

First, if you’re not familiar with the area, let’s locate Sheliak:

Sheliak, aka Beta (β) Lyrae, anchors the southwest corner of the constellation’s parallelogram.   (Stellarium screen image with labels added, click for a larger view).

Sheliak, aka Beta (β) Lyrae, anchors the southwest corner of the constellation’s parallelogram. (Stellarium screen image with labels added, click for a larger view).

And then we’ll zoom in on the immediate Sheliak environs and look at the chart we’re going to use for this tour:

Notice the stars from the previous tour are also shown. (Stellarium screen image again with labels added, click to enlarge).

Notice the stars from the previous tour are also shown. (Stellarium screen image again with labels added, click to enlarge).

We’ll start with Σ 2349, which is located due west of Sheliak at a distance of just under three arc minutes (2° 49’ to be exact).   If you look on the chart (click here to open it in a second window), you’ll see two faint stars which straddle a line drawn from Sheliak to Σ 2349.   HIP 91984, with a magnitude of 7.35, lies south of that line at a distance of one degree from Sheliak, and HIP 91563 (magnitude of 7.28) lies north of the line at a distance of two degrees from Sheliak. If you aim midway between those stars and continue due west, you’ll find Σ 2349 waiting patiently.

.

Σ 2349             HIP: 91235   SAO: 67164
RA: 18h 36.6m   Dec: +33° 28’
Identifier  Magnitudes   Separation   Position Angle    WDS
STF 2349 AB:  5.39,   9.40         7.40″           204°    2006
WAL 92   AC:  5.39, 12.10       32.90″           314°    1998
Distance: 522 Light Years
Spectral Classification: “A” is B8

This is the most difficult of the three stars we’re going to look at due to it’s relatively tight separation, coupled with a sizable four magnitudes of difference:

At 86x in the six inch refractor I was using, the secondary was a mere spark of light, although it was distinctly seen.   The “C” companion, at a magnitude of 12.10, required averted vision. Part of that was due to its faint magnitude, but the glare caused by the 6.71 magnitudes of difference between it and the white primary also contributed considerably to the difficulty. (East & west reversed to match the refractor view, click on the sketch to get a better look at “C”).

At 86x in the six inch refractor I was using, the secondary was a mere spark of light, although it was distinctly seen. The “C” companion, at a magnitude of 12.10, required averted vision. Part of that was due to its faint magnitude, but the glare caused by the 6.71 magnitudes of difference between it and the white primary also contributed considerably to the difficulty. (East & west reversed to match the refractor view, click on the sketch to get a better look at “C”).

 Click to enlarge.

Click to enlarge.

It was 1830 when F.G.W. Struve first measured the AB pair at 205.5° and 7.33”, and as Thomas Lewis’s compilation of observations at the right shows, there was little change in the next seventy-four years which followed. The WDS measure in 2006 shows not much happening here with the passage of an additional 102 years. The proper motion numbers in the WDS show the primary crawling along at a rate of +004 +003 (.004”/year east, .003”/year north). No numbers are shown for “B”, but considering the absence of significant change in the AB pair, “B” appears to be following the primary at very close to the same pace.

The three letter identifier of WAL 92 belongs to A. Wallenquist, who apparently had a good look at this area since he also discovered the “E” and “F” components of Nu-1 Lyrae on our last excursion.   According to the WDS data, he first measured the 12.10 magnitude “C” component of Σ 2349 in 1944 at 320° and 30”, and as you can see above, the most recent WDS measure for AC is 314° and 32.90”. But if you look carefully at the sketch above, you can see the position angle of AC is actually further north than 320 degrees.

I pulled up an image of Σ 2349 in Vizier to see what I could discover and found a star at that same location, which is labeled “1” in the image below:

This image has been flipped to match the orientation of my sketch above, which puts west at the left and north at the top.   Click on the image to enlarge it.

This image has been flipped to match the orientation of my sketch above, which puts west at the left and north at the top. Click on the image to get an easier to read version.

I also used the UCAC4 catalog in Vizier to get the magnitudes of the stars on the northwest side of the primary in order to pin down the correct star.  (Type UCAC4  — in upper case letters! – in the Vizier search box and then enter the WDS identification of 18366+3328 in the search box on the next screen.  After the date comes up, click on the last option at the bottom of the data [optical image] to get the chart above.  Click on any of the stars with red circles and its data will appear at the bottom of the chart.)

The only star that comes closes to the correct magnitude is the one I labeled  with a “1”, which UCAC4 has at a magnitude of 12.561.  Stars “2” and “3” are way too faint to be candidates.   Next I put the Aladin/Vizier measuring software to work to get the position angle of star number “1” and came up with 341°, but then got a surprise when I found the separation measured 46”, quite an increase from the 1988 WDS separation of 32.90”. Just to check further, I measured the distance and position angle from the primary to star number “2” at 296° and 51.42”, and from the primary to star number “3” at 319.5° and 57.0”

So something is wrong somewhere. My observation and the photo don’t match at all with the first (1944) and last (1988) measurements in the WDS.  Another celestial conundrum, once again.

Now we’ll reverse direction and head for one of Otto Struve’s discoveries, OΣΣ 172, which is located east and somewhat north of Σ 2349 at a distance of just under two degrees (1° 43’) – here’s our previous chart once again.   You can use 7.28 magnitude HIP 91563, located not quite halfway to OΣΣ 172 at a distance of 48’, as a stepping stone. Or you can center your finder midway between Sheliak and Σ 2349 and you should be able to spot OΣΣ 172 northeast of that spot at about 40’ away. A good 8×50 finder will show both stars, similar to what’s shown on the chart, which makes it easier to locate.

OΣΣ 172 (STTA 172)          HIP: 91940   SAO: 67311
RA: 18h 44.5m   Dec: 34° 00’
Magnitudes: 7.91, 8.66
Separation:  61.20”
Position Angle: 6° (WDS 2012)
Distance: 176 Light Years in Simbad; 168 Light Years in Hipparcos
Spectral Classifications: “A” and “B” are F8

This is a bright and wide pair which should also be suitable for a 60mm refractor.  On close examination, it’s a real beauty:

I detected a weak gold in both stars which was slightly more noticeable in the primary. Notice the surrounding field of stars seem to mainly arranged in groups of three and four. (East & west reversed once more, click on the sketch for a better view).

I detected a weak gold in both stars which was slightly more noticeable in the primary. Notice the surrounding field of stars seem to mainly arranged in groups of three and four. (East & west reversed once more, click on the sketch for a better view).

I didn’t catch it (not that I was looking for it) but S.W. Burnham mentioned seeing a faint star between the primary and secondary during one of the two observations he made of OΣΣ 172 in 1880 and 1905 (source):

Burnham on STTA 172

Chances are it would have been buried in the glare, anyway, since according to the UCAC4 data it’s a 13.76 magnitude star:

Click on the image for a larger view.

Click on the image for a larger view.

Because this is a wide pair, I was curious about whether the primary and secondary are related.   The WDS shows very similar proper motions for both the primary and secondary, which a chart from Simbad shows rather well:

The proper motion for the primary is +013 -015 (.013”/year east and .015”/year south), and for the secondary is +015 -017 (.015”/year east, .017”/year south). I zoomed into a six arcminute view for this chart, as opposed to the usual ten arc second view which is the default view in Simbad.   Click on the image for a larger view.

The proper motion for the primary is +013 -015 (.013”/year east and .015”/year south), and for the secondary is +015 -017 (.015”/year east, .017”/year south). I zoomed into a six arc minute view for this chart, as opposed to the usual ten arc second view which is the default view in Simbad. Click on the image for a larger view.

In order to get a better picture of where the two stars are in relation to each other, it would be helpful to know the distance of the secondary (which also is identified as BD +33 3191 and SAO 67314), but several sources failed to show any data.  Just to give you an idea of what’s available, I checked Hipparcos (available in Vizier by entering I/239/hip_main in the search box), Simbad, the Tokovinin Multiple Star Catalog, and the Yale Trigonometric Parallaxes (available in Vizier by entering I/238A/picat in the search box).  It’s rather unusual for an 8.66 magnitude star not to have a published distance or parallax, so it could be both stars are at the same distance.  Before I forget about it, many thanks to Bob Argyle and Neil English for the Tokovinin and Yale references.

Now let’s return to Σ 2349 in order to find our way to our last star, Σ 2333. If you look on our chart again, you’ll see we need to move southwest from Σ 2349 for about the same distance that separates Sheliak and Σ 2349, which is just under two degrees (1° 41’ in this case). You can use 7.60 magnitude HIP 90716 as a reference point since there’s nothing but a dark lane existing between Σ 2349 and Σ 2333.

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Σ 2333 (S 703)                     HIP: 90766
 SAO: 67059
RA: 18h 31.1m   Dec: +32° 15’
Identifier  Magnitudes    Separation  Position Angle     WDS
STF 2333 AB:  7.82,   8.57          6.40″         333°     2007
STF 2333 AC:  7.82, 12.90       164.40″           35°     2002
STF 2333 AD:  7.82, 13.70         85.80″         339°     2002
STF 2333 BC:  8.57, 12.90       161.20″           37°     2002
Distance: 707 Light Years (Simbad)
Spectral Classification: “A” is A0
The primary is white and the secondary radiates faint traces of orange – both stars are very similar in brightness. “C” wasn’t all that tough to pick out with direct vision in the six inch refractor. I looked long and hard for 13.70 magnitude “D”, but wasn’t able to detect any sign of it with averted vision.   (East & west reversed to match the refractor view, click on the sketch to enlarger-erate it).

The primary is white and the secondary radiates faint traces of orange – both stars are very similar in brightness. “C” wasn’t all that tough to pick out with direct vision in the six inch refractor. I looked long and hard for 13.70 magnitude “D”, but wasn’t able to detect any sign of it with averted vision. (East & west reversed to match the refractor view, click on the sketch to enlarger-ize it).

Click to enlarge.

Click to enlarge.

Even though Struve’s name is assigned to this system, Sir James South actually arrived here first with his measuring tools, coming up with a position angle of 336° 9’ and a separation of 6.43” for the AB pair in 1825. If you look at his observation at the left, you’ll see he started out using n p (north preceding) on his first measures of June 9th, 1825, and then switched to s p (south preceding) a month later on July 13th, and continued with south preceding on his final averages. But the final figure of 66° 9’ south preceding translates into 203° 51’, which is obviously way off, whereas 66° 9’ north preceding results in a more harmonious 336° 9’ (compare with the measurements shown below at the right). If you’re wondering how I translate those figures, at the end of this post I’ve attached a chart I use which comes from page 428 of this version of Admiral Willam H. Smyth’s Bedford Catalogue.  (The Bedford Catalogue is actually part two of a larger book, A Cycle of Celestial Objects, which is where that link takes you).

Click to enlarge.

Click to enlarge.

Six years later, when F.G.W. Struve arrived on the scene, he measured the position angle at 335.3° and the separation at 6.28”.   After that, as the excerpt at the right from Lewis’s book shows, through 1904 the position angle averaged out to 334.6° and the separation to 6.38”.  Comparing those numbers to the last WDS measure in 2007 shows little change occurring.

However, there’s an interesting difference in the proper motion numbers shown in the WDS and Simbad. The WDS has “A” and “B” moving at the same rate (.001”/year west, .002”/year south), while Simbad has “B” with a different rate and direction (.0065”/year west, .0036”/year north).   The WDS also shows PM numbers for “C” and “D”, but Simbad shows nothing for either star.

Proper Motions of Σ 2333
     Primary     Component
AB:    -001 -002     -001 -002 (006.5 +003.6 in Simbad)
AC:    -001 -002     -001 +002
AD:    -001 -002    +002 +016

Simbad also has a plot of the AB pair, which looks like this when you zoom into a three arc minute view:

Click on the chart for a larger view.

Click on the chart for a larger view.

Considering how little change in separation and position angle has taken place, it looks like the WDS data is more reliable, although in either case the motion is very minimal.

Since I had been unable to see it, I was curious about “D”, so I pulled up an Aladin photo of Σ 2333 and used the UCAC4 catalog to see if the magnitude there was fainter than what was shown in the WDS.   After using Aladin’s measuring software to pin down the location of “D”, I found UCAC4 listed the magnitude at 14.173, which may explain why I didn’t see it. On the other hand, even if the magnitude had been 13.70 per the WDS listing, it would have been tough to detect in the combined glare of the primary and secondary.

East and west are reversed here to match the orientation of the refractor view and avoid confusion.   Click on the photo for a better view.

East and west are reversed here to match the orientation of the refractor view and avoid confusion. Click on the photo for a better view.

So at the end of this three star adventure, we’re left with two head scratching contradictions, one being the correct position angle and separation for Σ 2349 AC, and the other the correct proper motion for the secondary of Σ 2333. While you’re busy solving those two issues, I’m going to pay a visit to a small constellation I haven’t given enough attention to over the last few years.   Meet me in Delphinus next!

Clear skies until then.   :cool:

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The Old Style Position Angle Chart

Click on the chart to get a larger and easier to read version.

Click on the chart to get a larger and easier to read version.

The numbers in the outer ring of this chart represent the current system of measuring position angles, while the numbers on the inside refer to the old style used above by James South (here’s his observation of Σ 2333 again).   So if we take Sir James’ June 9th, 1825, position angle of 66° 23’ north preceding and look it up on the inside ring of the chart, we get a reading of 336° 23’ on the outer ring.   If we use his July 13th, 1825, position angle of 65° 55’ south preceding, we find it equals 204° 05’ – which is nowhere close to Struve’s 1831 position angle of 333.3°.

The old style of measuring the position angle has the virtue of being more descriptive because it conveys the position angle in terms of the motion of a star through the eyepiece: preceding puts a secondary on the west side of a primary, following places a secondary on the east side of a primary. What stands out as rather odd, though, is the way south is placed at the top of the chart and north at the bottom. Although refractors were far more common in the early days of astronomy, star diagonals were apparently non-existent.  Viewing an object without a diagonal in the eyepiece end of the tube results in all four directions being reversed, just as they are on the chart. That’s the most likely explanation for the reversal of north and south, but it may also have to do with the orientation of the image in a Newtonian reflector, although that telescope design didn’t get much attention until William Herschel began producing and using them.   I haven’t been able to pin down the point at which the old style PA chart came into widespread use, but it’s possible Sir William had some influence since he was the first observer to produce a large number of double star measures, virtually all of which were done with Newtonian instruments.

South of Sheliak: Nu-1 and Nu-2 Lyrae, Σ 2397, Σ 2367 (with HJ 1336), and HJ 1352

Note at the beginning:  Many of these posts rely on the help and input of other people, which is especially the case for this one.   So before we get started, I want to extend my thanks to Brian Mason and Bill Hartkopf at the USNO/WDS for their help.  Brian sent me the HJ 1352 text file and a link to some valuable data I’ll use at a later date, and Bill Hartkopf was a huge help in making sense of the proper motion of HJ 1352, even going to the trouble of generating a new rectilinear chart of HJ 1352’s motion.   I couldn’t have done this one properly without their input.  It would be impossible to overstate the importance of these two guys to those of us who observe, measure, or write about double stars.

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Considering the relatively small parcel of celestial real estate covered by Lyra, it seems to be rather well stocked with a large collection of double and multiple stars.   If you start from any one of the four corners of the constellation, or from the apex at Epsilon (ε), you don’t have to go far before you find you’re surrounded by a maze of multiple points of light, many of them carrying double star designations.

For some reason Beta (β) Lyrae, aka Sheliak, caught my attention one night and, lured by the dual lighthouse-like beams radiating from Nu-1 (ν-1) and Nu-2 (ν-2) just south of Sheliak, I began to wander through the area.  In fact, it was such an enjoyable stroll that I came back later and wandered around west of Sheliak/Beta (β).  We’ll cover the southern stellar terrain in this tour and then look at what’s west of Beta (β) on the next tour.

First, let’s get oriented:

We’ll start immediately south of Beta (β) at Nu-1 (ν-1) and then move on to Nu-2 (ν-2).  (Stellarium screen image with labels added, click on the chart for a larger view).

Beta (β) Lyrae, aka Sheliak, is located at the southwest corner of Lyra. (Stellarium screen image with labels added, click to enlarge the chart).

And then let’s take a closer look at the area south of Sheliak:

We’ll start immediately south of Beta (β) at Nu-1 (ν-1) and then move on to Nu-2 (ν-2). (Stellarium screen image with labels added, click on the chart for a larger view).

We’ll start immediately south of Sheliak/Beta (β) at Nu-1 (ν-1) and then move on to Nu-2 (ν-2). (Stellarium screen image with labels added, click on the chart for a larger view).

Nu-1 Lyrae  (H V 40)  (8 Lyrae)               HIP: 92398   SAO: 67441
RA: 18h 49.8m   Dec: +32° 49’

Identifier   Magnitudes Separation Position Angle    WDS
H 5 40     AB:   5.93, 10.89     34.10″          76°    2009
H 5 40     AC:   5.93, 10.30     57.50″         120°    2009
WAL 95   AE:   5.93, 11.64     80.00″         350°    2008
WAL 95   AF:   5.93, 12.92     70.60″         349°    2002
H 5 40     CD: 10.30, 11.50     18.80″         212°    2008
Distance: 1309 Light Years (Simbad)
Spectral Classification:  “A” is B3

With six components, Nu-1 (ν-1) is a mesmerizing visual experience. I used a 9.25 inch SCT for the sketch below, but easily could have gone with as little as five inches of aperture, possibly even four, and still captured all the members of the tribe except for the difficult 12.92 magnitude “F”, which suffers from being within ten arc seconds of 11.64 magnitude “E”.

 If you’re looking for color here, all you’ll find is white, and lots of it.   “B” and “C” are easy enough to see, whereas “D” and “E” require you to look more closely. “D” is especially interesting because of its proximity to “C”. I did everything but stand on my head in hopes of catching a glimpse of “F”, but it’s just faint enough and close enough to “E” to be too tough of a task. (East and west reversed to match the SCT view, click on the sketch for a better view).

If you’re looking for color here, all you’ll find is white, and lots of it. “B” and “C” are easy enough to see, whereas “D” and “E” require you to look more closely. “D” is especially interesting because of its proximity to “C”. I did everything but stand on my head in hopes of catching a glimpse of “F”, but it was just faint enough and close enough to “E” to be too tough of a task. (East and west reversed to match the SCT view, click on the sketch to bring it to life).

William Herschel and his six inch reflector landed here first, discovering three of the components (A, B, and C) on September 24th, 1781 (source, scroll down to the twelfth title):

Wm. Herschel on Nu-1 Lyrae

The star he describes as north (n.) preceding is “B” and the south (s.) following is “C”, which is also the star he provides measurements for.   His 28° 27’ s. following translates to today’s 118° 27. Surprisingly Herschel missed (or ignored) “D”, which we’ll come back to in a moment. The last two components were added by A. Wallenquist, a Swedish astronomer, who uncovered “F” in 1934 and “E” in 1944.

If you look closely at the southwest edge of the sketch above, you’ll see a faint and shadowy pair, which is ES 2287 (18493+3301, 10.9 and 12.3, 3.9”, 293°, WDS 2011), discovered by T. E. Espin in 1927.   The secondary didn’t appear to me to be 1.4 magnitudes fainter than the primary as per the WDS data, but even the UCAC4 catalog (enter UCAC4-616-064988 in the box labeled “ID”) shows a magnitude of 12.489 for it. At any rate, it’s difficult to visually separate this pair because of their overall faintness and tight separation.

Getting back to Nu-1’s 11.50 magnitude “D” component, it looks as if Admiral William H. Smyth should be credited with first putting that star under a micrometer.   He measured the CD separation at 12.0” in 1836 with a PA of 208 degrees.   Since he hasn’t made an appearance here for a while, I’ll let him describe Nu-1 and get us started towards Nu-2 (ν-2). His magnitudes, which are considerably different than today’s, follow the letter designation of each star.

A quadruple star on the cross-piece of the Lyre. “A” 6, pale yellow; “B” 13, bluish; “C” 11, pale blue; “D” 15, blue; and there are three other stars in the field.   This object is 40 H V, who only measured “A” and “C”, though perceiving “B” and not “D”; he records it as triple. Sir James South, who appears not to have seen “B” or “D”, also observed the stars “A” and “C” . . .

This very delicate set is followed by ν2 Lyrae, a whitish star of the 6th magnitude, at an angle of 175°, and a distance of about 15’ of space; and they are both just to the south of β, the following object.”   (The Bedford Catalogue, pp. 432-33)

Nu-2 Lyrae  (HO 440)  (9 Lyrae)               HIP: 92405   SAO: 67446
RA: 18h 49.9m   Dec: 32° 33’
Magnitudes: 5.25, 12.70
Separation:  18”
Position Angle: 175° (WDS 2002)
Distance: 238 Light Years
Spectral Classification: “A” is A3

The primary is white, and you have to look closely to find the secondary hiding on the south side of the primary’s glare.   I could only see it with averted vision, and even that was tough at times due to the 7.45 magnitudes of difference between the two stars.   (East & west reversed once again, click on the sketch to catch the secondary).

The primary is white, and you have to look closely to find the secondary hiding on the south side (left in the sketch) of the primary’s glare. I could only see it with averted vision, and even that was tough at times due to the 7.45 magnitudes of difference between the two stars. (East & west reversed once again, click on the sketch to catch the secondary).

Click to enlarge.

Click to enlarge.

After reading Admiral Smyth’s description of Nu-2, it appears he didn’t see the secondary, which was also missed by William Herschel and James South. It wasn’t until 1892 that someone caught sight of it, that someone being George W. Hough, who did it with the 18.5 inch Clark refractor at the Dearborn Observatory.   As you can see by his comment in the excerpt above (source), even with that much aperture he had a difficult time spying the secondary.

Now we’ll move on to Σ 2397, which lies south and slightly west of Nu-2 (ν-2) at a distance of 1° 17’. You can use 6.05 magnitude HIP 92243, which is 54’ south of Nu-2, as a stepping stone to find your way. (Here’s the second chart above once again). I also labeled HIP 92396 (magnitude of 6.60) and HIP 91883 (magnitude of 5.65) on that chart, which come in handy as reference points.

Σ 2397                  HIP: 92178   SAO: 67378
RA: 18h 47.2m   Dec: +31° 25’
Magnitudes: 7.47, 9.08
Separation:  3.9”
Position Angle: 266° (WDS 2011)
Distance: 883 Light Years (Simbad)
Spectral Classification: “A” is G3

 If you like subtle colors, this is an appealing pair. The primary has a slight, but very noticeable white/gold hue. Both stars stood out distinctly with an 18mm Radian (136x) in the SCT. Also interesting, and well worth spending a few minutes on, is the surrounding field of stars.   (East & west reversed, click on the sketch for a much better view).

If you like subtle colors, this is an appealing pair. The primary has a slight, but very noticeable white/gold hue. Both stars stood out distinctly with an 18mm Radian (136x) in the SCT. Also interesting, and well worth spending a few minutes on, is the surrounding field of stars. (East & west reversed, click on the sketch for a much better view).

Click to enlarge.

Click to enlarge.

This pair was discovered by F.G.W. Struve in 1830, and they haven’t changed much since his original measurements of 3.72” and 267.4°, as you can see by comparing both the current WDS data and the various measurements shown at the right which followed those of Struve (from Thomas Lewis’s 1906 compilation of data on Struve’s discoveries).  The lack of significant change is reflected in the proper motion numbers for the primary and secondary, which are identical, +001 +016 (.001”/year east, .016”/year north).  These two stars are essentially moving through our galaxy in tandem, and provide an excellent example of a double star which is physically related, but not orbital.

Our next stop, Σ 2367, shining southwest of Σ 2397 at distance of 1° 42’, is a little tougher to get to. (Here’s the chart once more).   If you aim a line from Σ 2397 that runs midway between 7.55 magnitude HIP 92129 and 6.40 magnitude HIP 91533, it’ll point straight to Σ 2367.

Σ 2367                  HIP: 91636   SAO: 67250
RA: 18h 41.3m   Dec: +30° 18’

Magnitudes   Separation  Position Angle   WDS
AB: 7.70,   8.03        0.418″         73.5°   2014
AB,C: 7.70,   8.75      14.30″       192.0°   2012
AB,D: 7.70, 12.00      21.90″         84.0°   2007
AB,E: 7.70, 11.00    151.70″       341.0°   2002
AB,F: 7.70, 15.10      42.40″       173.0°   2007
Distance: 530 Light Years
Spectral Classification:  “A”, “B”, and “C” are all G5
Notes: Orbital period of AB is 93 years; AB,F is also BTG 2
The primary draws your eye immediately with its gold glow, which contrasts well with the subtle blue I saw in “C”, the star just south of the primary (left in the sketch). Lewis described both stars as yellow, which matches with their identical spectral classifications, so the blue I saw was likely caused by the proximity of the two stars. Hiding dimly in the west corner of the field is HJ 1336. (East & west reversed to match the refractor view, click on the sketch to go deeper).

The primary draws your eye immediately with its gold glow, which contrasts well with the subtle blue I saw in “C”, the star just south of the primary (left in the sketch). Lewis described both stars as yellow, which matches with their identical spectral classifications, so the blue I saw was likely caused by the proximity of the two stars. Hiding dimly in the west corner of the field is HJ 1336. (East & west reversed to match the refractor view, click on the sketch to go deeper).

Click to enlarge.

Click to enlarge.

This one was quite a sight when I first laid eyes on it. Your observational eye is immediately drawn to the two brightest stars in the field, 7.70 magnitude AB and 8.75 magnitude “C”, which actually stands in as the visual secondary in this case since the true secondary is hiding in the primary’s glow at a too-close-to-crack distance of 0.42”. There’s a plot of the 92 year orbit of AB in the WDS (shown here from the Stelledoppie page), which includes the separation and position angle I listed in the data above. If you have enough aperture, and cooperative seeing, this would be a great pair to attempt to split since they’re almost identical in magnitude. Lewis has an interesting diagram which comes close matching the WDS.

You have to look harder and closer to catch sight of twelfth magnitude “D” (I needed averted vision to see it) and eleventh magnitude “E” because of the glare caused by the AB,C pair.   After identifying “E”, I couldn’t help but wonder why that faint star to its north (right in the sketch) wasn’t included in the measurements for the stars surrounding AB-C, especially since a fifteenth magnitude star was added as “F” in 1998.

Also lying in the same field of view with Σ 2367 is an unexpected bonus, HJ 1336, an intricate and dim collection of stars in an interesting arrangement.   When I first saw them, I found them rather striking, despite their faint magnitudes . . . . . . .

HJ 1336               No HIP   SAO: 67236
RA: 18h 40.5m   Dec: +30° 17’

 Magnitudes   Separation Position Angle    WDS
AB  8.69, 12.00      16.90″          89°    2013
AC  8.69, 11.50      32.60″        174°    2012
AD  8.69, 12.70      33.30″        294°    2012
AE  8.69, 14.20      32.10″        337°    2012
Distance: ?????
Spectral Classification:  “A” is A0

. . . . . . . but I wasn’t sure if I was looking at a small cluster or a multiple star. I had to go back to Sky Tools 3 and Stelladoppie to find out what I was looking at. I missed twelfth magnitude “B” entirely on that first view, so I came back later with the six inch f/10 refractor and pried it out of the darkness with a 10mm Radian (152x).  I also tried my trusty 7.5mm Celestron Plössl (203x), but the murky air and poor seeing made the 10mm Radian a better choice, although I needed averted vision in both cases to detect it.

When you use high magnification and center HJ 1336 in your field of view, it’s actually a neat little system. “C” and “D” are not tough in a six inch refractor, and “B” just requires some patience and awareness of where to look.   (East & west reversed once more, click on the sketch to get a better view).

When you use high magnification and center HJ 1336 in your field of view, it’s actually a neat little system. “C” and “D” are not tough in a six inch refractor, and “B” requires some patience and awareness of where to look. (East & west reversed once more, click on the sketch to get a better view).

John Herschel discovered what is now AB and AD in 1828, and S.W. Burnham added what is now AC in 1901 (source).

Burnham on HJ 1336

The eleventh magnitude (“11 m”) star Burnham refers to on the last line is the AD pair that Herschel discovered.   Herschel’s observation of HJ 1336, which refers to that pair as AC, is shown below in the discussion of HJ 1352.  As you can see, there are times when you really need a scorecard to keep track of what went where when the identifications of components change as additional stars are added to a system.

Last on this tour is HJ 1352, which again requires some careful navigation (our chart once more). It lies one and a half degrees east and slightly south of Σ 2367. The only reasonably bright star along the way is 8.45 magnitude HIP 92261, which is a full degree east and a bit south of Σ 2367. You can also use 7.55 magnitude HIP 92129, which lies a bit more than a degree (1° 12’) east and very slightly north of Σ 2367, as a reference point. Either way, you’ll find HJ 1352 occupying the north end of a string of eighth magnitude stars aligned in a northwest-southeast diagonal.

HJ 1352               HIP: 92419   SAO: 86484
RA: 18h 50.1m   Dec: +29° 49’
Magnitudes: 7.8, 10.0
Separation:  13.7”
Position Angle: 249° (WDS 2006)
Distance: 1105 Light Years (Simbad)
Spectral Classification: “A” is B8

“Bears a singularly bright illumination.”

Those are John Herschel’s words, and as the sketch below shows, the primary stands out distinctly from the rest of the field:

I found the primary’s white glow was strong enough that the secondary was mainly an averted vision affair in the 10mm Radian, although it was also easy to spot with a 14mm Radian (109x) and some averted vision. The pair is surrounded by a very busy field of stars – in fact, I gave up trying to capture all the faint ones. There are two faint pairs shown, one at the east edge of the view (bottom) and one near the west edge (at about 11 o’clock), neither of which are cataloged as doubles from what I could determine. (East & west reversed, click on the sketch for a much better view).

I found the primary’s white glow was strong enough that the secondary was mainly an averted vision affair in the 10mm Radian, although it was also easy to spot with a 14mm Radian (109x) and some averted vision. The pair is surrounded by a very busy field of stars – in fact, I gave up trying to capture all the faint ones. There are two faint pairs shown, one at the east edge of the view (right edge of sketch) and one near the west edge (at about 8 o’clock), neither of which are cataloged as doubles from what I could determine. (East & west reversed, click on the sketch for a much better view).

This is another 1828 discovery by John Herschel — his observation is shown below at the bottom of the page (source):

Herschel’s observations of HJ 1336 and HJ 1352 are in the yellow boxes, and if you look in the middle of the page, you’ll see his data on Epsilon Lyrae (the stars labeled Σ. 2382, Sh. 277, and Σ. 2383). Click to enlarge the image.

Herschel’s observations of HJ 1336 and HJ 1352 are in the yellow boxes, and if you look in the middle of the page, you’ll see his data on Epsilon Lyrae (the stars labeled Σ. 2382, Sh. 277, and Σ. 2383). Click to enlarge the image.

Even though Herschel included the comment “Well measured”, it’s likely the separation (6″) was estimated.   If we look in Burnham’s 1906 Catalog , we find measurements by Otto and Hermann Struve’s from 1879 and 1885 which cast a doubtful light on that six arc second figure:

Otto and Hermann Struve on HJ 1352

And if we jump ahead to 1909, we find S.W. Burnham’s efforts (source) confirm the Struve measures — but notice the four degree change in position angle, which Burnham comments on :

Burnham on HJ 1352

Curious about that rapidly changing position angle, I sent a request to Brian Mason for the text file listing all the measures for HJ 1352 from 1828 to the most recent in 2006, and used the data to generate a chart showing the changes over that 178 year period.  There were a cluster of five measurements between 1906 and 1918, and three each in 2002 and 2006.  To avoid cluttering up the chart below with dots stacked on top of one another, I averaged each of those clusters to come up with one measure for each time period, resulting in this plot:

This is a mirror-reversed image to match the orientation of the sketch above of HJ 1352, meaning north is at the top and west is at the left.   (Click for a larger view).

This is a mirror-reversed image to match the orientation of the sketch above of HJ 1352, meaning north is at the top and west is at the left. John Herschel’s 1828 separation is clearly out of place. If you estimate the actual separation in 1828 at nine arc seconds, then his position angle is a better match with the other data, although even then it looks like it may be off a few degrees. (Click for a larger view).

You can see the secondary is steadily moving both north and west, which in fact is exactly what the proper motion figures show: -017 +005 (.017”/year west, .005”/year north).  On the other hand, the primary, with a proper motion of +003 -001 (.003”/year east, .001”/year south), is hardly moving at all .

When we compare HJ 1352 with our earlier discussion above of Σ 2397, we find although the directions are different, the rates of motion are very similar: +001 +016 (.001”/year east, .016”/year north) for the Σ 2397 pair and -017 +005 (.017”/year west, .005”/year north) for the HJ 1352 secondary.  The main difference is the primary of HJ 1352 is virtually stationary, so about 99% of the change in position angle and separation is a result of the secondary moving away from the primary.   Which is a pretty darn clear indication the two stars aren’t physically related in any way.

Amazing what a few numbers can tell you about a pair of stars!

Next time out, we’ll start at Sheliak again and head due west to see what we can find.

Clear Skies until then!   :cool:

Epsilon Lyrae Revisited, and a Few Friends: Bu 51, HJ 1341, and BLL 35

.

“This wide pair is readily seen with the naked eye.”
S.W. Burnham
A General Catalogue of Double Stars Within 121° of the North Pole, Part II,
p. 805

 

Well, maybe . . . . .  if you happen to have S.W. Burnham’s eagle-sharp eyes.  I’ve tried this trick many times, and the best I can manage is a ghost-like elongated impression of more than one star, but not quite two.  For comparison, the next time Taurus is in the sky, try Theta (θ) Tauri, an evenly matched pair separated by 341.20″.  Under cooperative skies, it’s a breeze.  Epsilon (ε) Lyrae is about thirty percent closer together (207.9″) than Theta (θ) Tauri, which explains why it’s a tougher visual split.

At any rate, the Lyra pair has a magnetic lure I find impossible to ignore — if it’s anywhere in the sky, I always point the nearest telescope at it.  Every time I look at those two pairs of stars, the routine is always the same: focus carefully until the CD pair disengage from each other; adjust the focus a few tenths of a turn more until the bear-hugging AB pair become distinct dots of white light, one slightly fainter than the other; and take note of the small sphere of faint white light lying between and east of a line thrown from AB to CD.

And then move on to other things.

But there’s more to Epsilon (ε) Lyrae than the AB-CD pair – aka the “Double-Double” – that most everyone is familiar with, and I’ve long had intentions of looking under the hood, so to speak, to see what else there is to see.  In fact, that plan has been parked forever on my List of Things to Do When I Get Around to It Provided I Can Remember It.  Of course I never quite managed to get around to it, even though I did remember it.

Finally, after some serious star-hopping one dark night in search of obscure pairs in the neighborhood of Sheliak, aka Beta (β) Lyrae, I could resist an in-depth perusal no longer.

First, in case you’ve never been where we’re going, here’s a chart to get oriented:

Think of this as the S.W. Burnham view of Lyra, since you won't see Epsilon as two distinct stars . . . . . . .  unless you have very sharp eyesight!   (Stellarium screen image with labels added, click for a larger view).

Think of this as the S.W. Burnham view of Lyra, since you won’t see Epsilon as two distinct stars . . . . . . . unless you have very sharp eyesight! (Stellarium screen image with labels added, click for a larger view).

And next, here’s the entire roster of measurements and surrounding components currently listed in the WDS.  A word of warning: don’t panic — we’re not going to use the whole list!   It’s only here to jolt you back to life in case your eyes are at half-mast after a long night behind or beside a telescope.

Epsilon Lyrae                     HIP: 91919   SAO: 67310
RA: 18h 44.3m   Dec: +39° 40’
Distance  AB: 162 Light Years  CD: 162 Light Years (both from Simbad)
Spectral Classifications: “A” is A3, “B” is F0, “C” is A6, “D” is A7
Notes:  AB is 4 Lyr, H II 5, Σ 2382, SHJ 276
.          CD is 5 Lyr, H II 6, Σ 2382, SHJ 278

discov# comp  first  last  pa   sep mag1 mag2
STF2382 AB 1777 2013 346    2.3   5.15   6.10
STFA 37 AB,CD 1830 2013 171 207.9   4.67   4.56
STFA 37 AD 1903 2012 172 208.7   5.15   5.38
STFA 37 AI 1863 2012 138 150.0   5.15 10.43
STFA 37 BC 1903 2011 172 210.9   6.10   5.25
STFA 37 BD 1903 2002 172 210.0   6.10   5.38
STFA 37 BI 1872 2002 137 149.6   6.10 10.43
CHR 77 Ca,Cb 1985 2005 225     0.1   5.25
STF2383 CD 1777 2013   78     2.4   5.25   5.38
SHJ 277 CD,F 2012 2012     0   92.2  11.71 11.20
SHJ 277 CD,G 2012 2012 292   75.6  11.71 13.83
SHJ 277 CD,H 2012 2012 312   95.8  11.71 13.22
STF2383 CE 2000 2012 333   63.1   5.25 11.71
STFA 37 CI 1863 2012   37 120.4   5.25 10.43
STFA 37 DI 1909 2002   36 122.4   5.38 10.43
SHJ 277 EF 1831 2012   37   45.3  11.71 11.20
SHJ 277 EG 1878 2002 237   49.3  11.71 13.83
STFA 37 EI 2011 2011   68 108.9  11.71 10.43
SHJ 277 GH 1878 2012 358   35.6  13.83 13.22

What you have here is a whole bunch of measures busily crossing back and forth between the various components like a spider web gone berserk.  So before your eyes glaze over and you decide to give up double stars forever and pursue something less intimidating – like fifteenth magnitude galaxies with binoculars — it’s not as complex as it looks.  Let’s boil the long list above down to basics.

Apart from the AB and CD pairs your eyes normally light on every time you focus your gaze on Epsilon Lyrae, there are only five additional components to look for, and one of those five you’ve probably noticed almost every time you’ve looked at Epsilon – that would be “I”, the star lying east of the line running between AB and CD, the one I obliquely referred to in the last line of the second paragraph above.

Which only leaves four components, all faint, most of which will be new to many observers.

So here are the essentials, with the data for the ever-present AB and CD pairs taking up the first three lines, and “I” on the fourth line.  Our focus will be on the E through H components on the next four lines.

Epsilon Lyrae                     HIP: 91919   SAO: 67310
RA: 18h 44.3m   Dec: +39° 40’
Distance: 162 Light Years
Spectral Classifications: “A” is A3, “B” is F0, “C” is A6, “D” is A7
Notes:  AB is 4 Lyr, H II 5, Σ 2382, SHJ 276
.          CD is 5 Lyr, H II 6, Σ 2382, SHJ 278

UCAC4 “f”
discov# comp  first  last  pa   sep mag1 mag2 Magnitudes
STF2382 AB 1777 2013 346    2.3   5.15   6.10
STF2383 CD 1777 2013  78    2.4   5.25   5.38
STFA 37 AB,CD 1830 2013 171 207.9   4.67   4.56
STFA 37 AI 1863 2012 138 150.0   5.15 10.43        9.77
STF2383 CE 2000 2012 333   63.1   5.25 11.71       11.97
SHJ 277 CD,F 2012 2012     0   92.2  11.71   11.2       12.38
SHJ 277 CD,G 2012 2012 292   75.6  11.71 13.83       13.97
SHJ 277 CD,H 2012 2012 312   95.8  11.71 13.22       13.54

As for that new column I added at the far right, ignore it for the moment – we’ll come back to it in a few paragraphs.

So let’s look at what there is to see when you lasso Epsilon Lyrae with six inches or more of aperture (under dark and cooperative skies, a five inch refractor could probably duplicate what my six inch refractor saw).

The six inch view is in the center of this sketch, and to the right is an inset showing the view in a 9.25 inch SCT, which also identifies all the components.  (East & west reversed to match the views in the refractor and SCT – click on the sketch to get a better look at the four faint components, E through H).

The six inch view is in the center of this sketch, and to the right is an inset showing the view in a 9.25 inch SCT, which also identifies all the components. (East & west reversed to match the views in the refractor and SCT – click on the sketch to get a better look at the four faint components, E through H).

As I mentioned, I’ve seen “I” many times, although I never realized it was listed as a component of Epsilon Lyrae.  You can’t miss it, even in a 60mm refractor.  To digress for a moment, you may see the AI pair referred to as STF 4037 in some catalogs or atlases, instead of STFA 37 as shown in the WDS data above.  The “A” in the WDS identification refers to the stars in F.G.W. Struve’s first appendix, but prior to the WDS usage, some observers made a practice of adding 4000 to the appendix number.  There are actually two Struve appendices – the WDS identifies the stars in the second appendix as STFB, and yes, those stars were once identified by adding 5000 to the appendix number.  In fact, the “B” and “C” components of Altair (aka Alpha (α) Aquilae, aka STFB 10), are still identified in Simbad as STF 5010B and  STF 5010C.  (Thanks to Bill Hartkopf at the USNO/WDS for much of that information).

But enough digressing – back to “E”, “F”, “G”, and “H”.

In my six inch f/10 refractor, “E” popped into view first, and then with an application of careful and persistent averted vision, I finally managed to get “F” to pop out of the glare.  That’s the opposite of what I expected since the WDS listing shows “F” is the brighter of the two at a magnitude of 11.2 versus 11.71 for “E”.  And with “E” lying about thirty arc seconds closer to the glare of the CD pair, it was even more surprising.

That drove me to the UCAC4 catalog, which includes a magnitude category designated as “f”, short for “fit model magnitude” (more information on how to access that catalog is in the discussion of HJ 1341 below).  That particular magnitude is frequently a better match with what you’ll see visually, and in this case it reverses the relative brightness of “E” and “F”.  As the right column in the table above shows, UCAC4 has “E” at 11.97 and “F” at 12.38.  That’s not a lot of difference, but at any rate it’s a better relative comparison of the magnitudes of the two stars compared to the WDS values, and it explains why “F” was playing hide and seek in the glare of AB and CD.  Based on my experience, though, there seems to be more of a difference in magnitude between “E” and “F” than the .41 shown by the UCAC4 data.

Since both “G” and “H” managed to stay hidden from my six inch refractor, I returned the following night with a 9.25 inch SCT to see what would happen.  I was able to catch both of them using a 26mm Celestron Plössl (94x), a 24mm Brandon (102x), and an 18mm Radian (136x).  “H” popped into view first and was visible with direct vision most of the time.  “G” was much tougher, mainly due to its closer proximity to the glare of CD.  It was strictly an averted vision, now-you-see-it-now-you-don’t, apparition.  That experience matches the relative magnitudes shown for the two stars in the WDS, as well as the UCAC4 catalog which shows each of them to be slightly fainter than the WDS data.

Click to enlarge the image.

Click to enlarge the image.

These four stars are described in the WDS notes file (scroll halfway down the page) as the SHJ group, which is fitting since James South (the “S” in SHJ) and John Herschel (the HJ) appear to have been the first observers to discover the brighter of the four stars, “E” and “F.”  And they didn’t have an easy time of it, based on the description shown at the right from their 1824 Catalog (scroll down to the bottom of that page).

Not surprisingly, they saw “I” easily enough with their 3.9 and five inch refractors (the “Equatorials” referred to in their account), but had no hint of either of the two stars now designated as “E” and “F”.  Nor did they catch sight of either of those two stars with six and nine inch reflectors.  It wasn’t until they aimed John Herschel’s twenty inch reflector at Epsilon Lyrae that “E” and “F” appeared in the field of view.  Based on that experience, they described the two stars as “each of the 15th or 20th magnitude”, which is more than a little off the mark of course, but probably reflects the way they interpreted the relative performances of the various apertures they used.

The first dates of measure in the WDS for “G” and “H” are listed as 1878.  I’m not sure at this point who measured or discovered the two stars, but apparently it wasn’t S.W. Burnham, even though that date points to him.  But he does refer to them in his 1906 catalog, describing them as “light tests for small apertures”.  I wish I knew what apertures he had in mind, since my experience is they’re well out of reach of a six inch refractor.

In his 1906 catalog, Burnham labeled the four SHJ 277 stars as “A” through “D”.  His AB refers to present-day EF, and his CD refers to what is now GH.

In his 1906 catalog, Burnham labeled the four SHJ 277 stars as “A” through “D”. His AB refers to present-day EF, and his CD refers to what is now GH.

Epsilon Lyrae has some multiple star company surrounding it, all of which are worth looking for since it’s possible to see them while Epsilon is still in the field of view.  You’ll need at last six inches of aperture to catch two of them, Bu 51 and HJ 1341.

We’ll start with Bu 51, which is located east of the Double-Double.

Bu 51      No HIP or SAO Numbers
RA: 18h 45.7m   Dec: 39° 42’
Magnitudes   AB: 9, 11.95    BC: 11.95, 12.90
Separation    AB: 74.10”       BC: 6.10”
Position Angle  AB: 185° (WDS 2002)   BC: 297° (WDS 2002)
Distance:  ?????
Spectral Classification:  “A” is M0

Start with Epsilon Lyrae in the center of the field of view and then slide it toward the west corner of the view until the ninth magnitude primary of Bu 51 comes into view.   The BC pair will appear as a ghost-like star attempting to split in two.

 In the six inch refractor, BC appears as a faint elongated smudge trying to come apart.  In the 9.25 inch SCT, the two stars were distinctly separate in an 18mm Radian (136x) and, surprisingly, not much brighter despite the larger aperture.  (East & west reversed to match the refractor and SCT views, click on the sketch for a better look at the BC pair).

In the six inch refractor, BC appears as a faint elongated smudge trying to come apart. In the 9.25 inch SCT, the two stars were distinctly separate in an 18mm Radian (136x) and, surprisingly, not much brighter despite the larger aperture. (East & west reversed to match the refractor and SCT views, click on the sketch for a better look at the BC pair).

S.W. Burnham discovered this triple star in 1870 using his six inch Clark refractor, so obviously it can be seen more clearly in a six inch than the view I had of it:

Burnham on Bu 51

Click to enlarge the image.

Next on the list is HJ 1341, another faint and ghost-like pair, and with a little care, we can pull our third pair, BLL 35, into the scene as well.  Again, start with Epsilon Lyrae centered in the field of view, and this time slide it to the east corner of the field.

You’ll see a faint triangle of eleventh to twelfth magnitude stars come into view in the west edge of the field.  The star holding down the north corner of the triangle is HJ 1341.  Because both stars are faint, I had to look closely to catch the secondary.  With Epsilon Lyrae wedged tightly in the east corner of the field and HJ 1341 parked as close to the opposite edge of the field as possible without losing it, you’ll find BLL 35 shining in the southwest corner of the field.  In addition to a much brighter primary than Bu 51 and HJ 1341, the secondary is about a magnitude brighter than the additional components of the previous two stars.  The pair is also wider, and the orange hue of the 6.64 magnitude primary is obvious.  (East & west reversed once more, click on the sketch for a better view).

You’ll see a faint triangle of eleventh to twelfth magnitude stars come into view in the west edge of the field. The star holding down the north corner of the triangle is HJ 1341. Because both stars are faint, I had to look closely to catch the secondary. With Epsilon Lyrae wedged tightly in the east corner of the field and HJ 1341 parked as close to the opposite edge of the field as possible without losing it, you’ll find BLL 35 shining in the southwest corner of the field. In addition to a much brighter primary than Bu 51 and HJ 1341, the secondary is about a magnitude brighter than the additional components of the previous two stars. The pair is also wider, and the orange hue of the 6.64 magnitude primary is obvious. (East & west reversed once more, click on the sketch for a better view).

BLL 35        HIP: 91820   SAO: 67287
RA: 18h 43.3m   Dec: +39° 18’
Magnitudes: 6.64, 10.35
Separation:  62.7”
Position Angle: 191° (WDS 2012)
Distance: 1359 Light Years
Spectral Classification: K5
Note: “A” is a spectroscopic binary

Never having come across the BLL identifier before, I looked it up and found it referred to R.S. Ball, who among other things, used Lord Rosse’s 72 inch reflector at Birwell (scroll down to the bottom of the page to see the monster) to discover eleven NGC objects.  In 1874 he was appointed Royal Astronomer of Ireland, and later wrote books on astronomy, kinematics and mathematics.

Click to enlarge.

Click to enlarge.

I had no luck turning up Ball’s 1877 observation in any of his publications, but I did find it in Burnham’s 1913 Proper Motion Catalog, which included measures made by Burnham in 1910.  At the time of Burnham’s observations, the pair hadn’t yet been cataloged with an assigned prefix or number, so he used the Bonner Durchmusterung (DM) number for identification.  His reference to “C” as being DM (39°) 3504 is an error since there is no “C”.  Simbad, which I checked for confirmation, identifies “B” with that number.

HJ 1341     No HIP or SAO Numbers
RA: 18h 42.6m   Dec: +39° 37’
Magnitudes: 11.39, 11.8
Separation:   8.8”
Position Angle: 286°  (WDS 2012)
Distance: ?????
Spectral Classifications:  Both stars are G

Click to enlarge.

Click to enlarge.

John Herschel’s 1828 observation of this pair of stars is shown at the left.  Also included there are his observations of the AB and CD components of Epsilon Lyrae, as well as the “E” and “F” components, whose estimated magnitudes he places at fourteen and fifteen, an improvement over the fifteen to twenty he and James South had estimated in 1823. (Source — in volume 4)

As I was comparing my sketch to the WDS data, I stumbled into an issue with the relative magnitudes of the primary and secondary – as in which of the two stars is actually the brighter of the pair.  (For those not familiar with the practice, position angle (or PA) is measured from the brightest to the faintest of a given pair of stars).  If you look closely at Herschel’s measure in the excerpt above, you’ll notice he shows the PA at 105°, meaning he saw the star on the east side of the pair as being the fainter of the two stars.  That differs from the WDS PA above by 181 degrees – in other words, Herschel’s impression of the brightness of the two stars was the reverse of what was seen when the 2012 WDS measure was made.  Just to add more mystery to the mystery, if you look at my sketch above, you’ll notice I saw the relative magnitudes of the two stars in the same way Herschel did.  So why is the WDS measure treating the two stars as though their relative magnitudes are opposite of the way John Herschel and I saw them?

HJ 1341 is at the center, click to enlarge. (North is at the top, west at the left — 1993 POSS II Band F photo).

First, if you look at various photos of HJ 1341, as in the one at the right, it’s hard to tell which of the two stars is the brightest.  That led me to Vizier, where I turned to the UCAC4 catalog in search of magnitudes.  (Enter the WDS identification for HJ 1341, 18426+3937, in the Target box to get the UCAC4 data).  Vizier has an option (last one at  the bottom of the list of data: “Optical Image of this region . . . .”) which allows you to pull up an Aladin photo of the area on which it identifies the UCAC4 stars in that data by super-imposing small circles on them.  Clicking on any star bearing the circle will list its UCAC4 data below the photo, including magnitudes.  That resulted in the photo below, with the data shown below it.

Click to enlarge.

To see the data more clearly, click on the image to enlarge it. (NOTE: In order to avoid the confusion caused by conflicting orientations, I’ve flipped the image to match the SCT sketch of HJ 1341, meaning east and west have been reversed).

Since it’s debatable which of the two stars of HJ 1341 is the primary, I numbered them with “1” and “2” as shown in the photo.  The UCAC4 catalog assigns an “f” magnitude of 11.694 to star “1” and assigns star “2” an “f” magnitude of 11.80.  In that case, the WDS PA of 286° would be correct.  However, you can’t see it in the photo above – BUT — when you click on star “1” and then click on star “2”, the software returns a position angle of 105° — which is puzzling . . . . . . .

. . . . . . but maybe it’s because Simbad shows star “1” as the fainter of the pair.  Specifically, Simbad lists star “1” with a visual magnitude of 11.3 (it identifies that star as CCDM J18426+3937B) and assigns star “2” (which it identifies as CCDM J18426+3937A) a magnitude of 11.2 — in which case, John Herschel’s PA of 105° would be correct.

All I can add is I looked at HJ 1341 four times – twice with the six inch refractor and twice with the 9.25 inch SCT – and every time the fainter star was on the east side of the pair (the one I labeled “1” in the image above).

To pile more mystery on top of enough mystery already, Stelladoppie designates the primary as TYC 3122-02059-1.  And there’s no need to puzzle over which of the two stars of HJ 1341 are being referred to, since neither one is TYC 3122-02059-1.  At least according to the UCAC4 catalog — it identifies the real TYC 3122-02059-1 as the 10.656 magnitude star directly south of the HJ 1341 pair at a distance of 104”, which I’ve labeled it on the image above.

All of which goes to show you just never know what kind of confused and entangled web you’re liable to be ensnared by in the dark of the night.

On to Sheliak next time out!  Clear Skies! :cool:

On the Hercules-Draco Border – South of Rastaban: Σ 2142, Σ 2167, Fox 202, and Σ 2229

During our last exploration we star-hopped our way through a distinctive area of Hercules south of Gamma (γ) Draconis, aka Eltanin, which is situated at the southeast corner of Draco’s head. For this excursion we’ll see what we can turn up in a seldom-traveled area of the sky beneath the southwest corner of the circuitous Dragon’s four-sided head, which is occupied by Beta (β) Draconis, aka Rastaban, aka Alwaid (scroll down to the middle of the page). It’s an eye-catching yellow-white third magnitude star which also just happens to carry a double star designation, Bu 1090. With magnitudes of 2.79 and 14.0 separated by 4.40”, it’s another one of S.W. Burnham’s vision tormenting pairs. I notice the most recent observation of that pair was in 1939, which apparently means others have had a hard time detecting the 14th magnitude secondary as well, especially since a third component was added as recently as 2012 (magnitude of 12.70 at 118.90”) without updating the measurements of the 14th magnitude star.

At any rate, to get where we’re going it’s much easier to start from Eltanin again and then drop south and work our way west through a rather dim and forlorn stretch of sky.

First, though, here’s a wide view of or we’re where going:

Stellarium screen image with labels added, click for a larger view.

Stellarium screen image with labels added, click for a larger view.

And now we’ll zoom in on the area south of Eltanin and Rastaban:

Starting at second magnitude Eltanin, we’ll hop southwest almost a degree and a half (1° 23’) to fifth magnitude 30 Draconis. From there it’s a full degree further southwest to 7.0 magnitude HIP 86869, which is also double (TDT 485), although with a separation of .80” and a 2.33 magnitude of difference (7.29, 9.62) we’ll pass on it this time out.   However, with HIP 86869/TDT 485 centered in your eyepiece, you’ll find our first target, Σ 2229 shining in the same field just 12’ northeast of it. (Stellarium screen image with labels added, click on the chart to enlarge it).

Starting at second magnitude Eltanin, we’ll hop southwest almost a degree and a half (1° 23’) to fifth magnitude 30 Draconis. From there it’s a full degree further southwest to 7.0 magnitude HIP 86869, which is also double (TDT 485), although with a separation of .80” and 2.33 magnitudes of difference (7.29, 9.62) we’ll pass on it this time out. However, with HIP 86869/TDT 485 centered in your eyepiece, you’ll find Σ 2229, our first target, shining in the same field just 12’ northeast of it. (Stellarium screen image with labels added, click on the chart to enlarge it).

(You can also start at Rastaban and take this tour in reverse order (which is what I did originally) by following an arc of stars outlined in the chart above by 6.45 magnitude HIP 85268, 5.65 magnitude HIP 84950, 7.45 magnitude HIP 84511, 6.25 magnitude HIP 84021, 7.10 magnitude HIP 84072, and 6.45 magnitude HIP 83857, and on to Σ 2142. That’s a bit trickier, but it’s a good way to sharpen your star-hopping dexterity).

Σ 2229            No HIP   SAO: 30555
RA: 17h 45.9m   Dec: +50° 11’
Magnitudes: 8.31, 10.30
Separation:  6.6”
Position Angle: 338° ( WDS 2006)
Distance: ?????
Spectral Classification: “A” is K2
Note: Simbad shows “B” at a visual magnitude of 9.76

The seeing wasn’t cooperating at the time I was looking at this relatively tight pair, so I had to settle for a lowly magnified view in order to catch a firm glimpse of the secondary:

The primary had a very delicate and beautiful red-orange-white tint, and even in the wider field provided by the 26mm Plössl, the secondary, which was just a bit more than a spark of light, was clearly separated. (East and west reversed to match the SCT image, click on the sketch to get a better view of the secondary).

The primary had a very delicate and beautiful red-orange-white tint.  Even in the wider field provided by the 26mm Plössl, the secondary, which was just a bit more than a spark of light, was clearly separated from the primary. (East and west reversed to match the SCT image, click on the sketch to get a better view of the secondary).

Shown in the southwest corner of the view is the star we used to locate Σ 2229, HIP 86869. As I mentioned above, it’s also a double star, TDT 485. The WDS shows magnitudes of 7.29 and 9.62, a separation of .80”, and a position angle of 328°, all based on 1991 data from the Tyco Double Star Catalog.  That’s the only existing measure, so here’s a chance for someone with a well-developed photographic double star technique to make a contribution.

Click to enlarge.

Click to enlarge.

It looks like there has been some change in the Σ 2229 pair since Struve’s first measurements, although not much. I added older WDS data I dug up to the excerpt at the right from Lewis’s compilation of Struve’s double stars and some distinctive irregularities are obvious. Mädler (Maed) shows a large increase in separation in 1843 to 6.72” which stands out from the rest of Lewis’s data, while the WDS data shows a 1931 separation of 5.3” which isn’t repeated by any of the other measurements.   The WDS data also shows a surprising variation in position angles which don’t match the pattern of the data listed by Lewis.

Simbad shows a proper motion for the primary of -006 -010 (.006”/year west and .010”/year south) and -008 -007 for the secondary (.008”/year west and .007”/year south), which isn’t much, but it does mean the two stars should be separating slowly as the position angle decreases very gradually:

Click to enlarge the image.

Click to enlarge the image.

Based on Simbad’s PM numbers, I would expect the 2006 WDS position angle is likely to be more accurate than the numbers shown from 1931 and 2002. The 2006 PA also matches the slowly decreasing trend in position angles from 1830 to 1905 shown in Lewis’s data. At any rate, here’s another opportunity for a photographic measurement.

Now on to our next pair, Fox 202 (here’s our last chart once more). From HIP 86869/TDT 485 move almost a full degree (52’) southwest to 6.60 magnitude HIP 86446, then another 40’ in the same direction to 7.5 magnitude HIP 86418, and then 32’ west and slightly south to 7.35 magnitude HIP 85880. Fox 202 lies 27’ northwest of it at the north end of two 9.5 magnitude stars that point almost directly to it.

Fox 202           HIP: 85769   SAO: 46777
RA: 17h 31.6m   Dec: 49° 43’
Magnitudes: 8.1, 10.8
Separation:  55.40”
Position Angle: 237° (WDS 2003)
Distance: 937 Light Years (Simbad)
Spectral Classification: “A” is K0

The primary and secondary are located at the center of this field of view, competing for notice with a scattering of stars of slightly fainter magnitude to the southeast. I saw white in the primary and had to use averted vision to catch sight of the secondary. (East & west reversed to match the refractor view, click on the sketch for a better version).

The primary and secondary are located at the center of this field of view, competing for notice with a scattering of stars of slightly fainter magnitude to the southeast. I saw white in the primary and had to use averted vision to catch sight of the secondary. (East & west reversed to match the refractor view, click on the sketch and it’ll spring to life).

Also seen in the sketch above at the extreme east edge of the field of view is Hu 1282, a dim pair discovered in 1904 by W.J. Hussey.   It’s just a bit tight and faint for my astronomical apparatus, with magnitudes of 10.3 and 11.3, a separation of 0.5”, and a PA of 142° (WDS 2010).

 Click for a larger view.

Click for a larger view.

Fox 202 was discovered by Philip Fox in 1909 with the observatory’s 18 ½ inch Clark Refractor (shown full size at the bottom of this piece) while he was employed at the architecturally intriguing Dearborn Observatory outside of Chicago.

It took a while, but I found Fox’s original observation of what was later cataloged as Fox 202 in a 1915 publication of Dearborn Observatory. Fox identified the pair with the primary’s BD (Bonner Durchmusterung) number, +49 2653, which I was able to cross-reference in Stelladoppie and Simbad with Fox 202.

Click to enlarge.

Click to enlarge.

There’s a surprising difference between the 2003 data listed in the WDS and Fox’s observation. As the excerpt at the left shows, he made two measures, both of which were very consistent. Simbad shows a small amount of proper motion for the primary, +017 +005 (.017”/year east and .005”/year north), but none for the secondary.   Since the small amount of motion of the primary is nowhere near enough to account for the ten arc seconds of change in separation from 1909 to 2003, I became curious about what measurements between those of Fox in 1909 and the WDS data of 2003 might show.  Brian Mason at the USNO, home of the Washington Double Star Catalog (WDS), was kind enough to send me the text file for Fox 202, and I was surprised at what I found.

The WDS text files contain all known published measures of a given double star, which is always handy data to have in order to see how a pair of stars change over time. In the case of Fox 202, I found there was only one additional measure made between 1909 and 2003.  But just as important, the text file also contains a bibliographical reference to the original source of each measurement. The reference for the only additional observation of Fox 202 led me to the Webb Society’s Double Star Circular Number 15:

Tobal on Fox 202As you can see, that data is much closer to Fox’s 1909 measures, and very close to what you would expect to see based on the proper motion of the primary. I also learned from the introductory material to the data that the measure was made on a digitized photographic plate by Tòfal Tobal at the Garraf Astronomical Observatory in Spain as part of a comprehensive program to measure what at the time was a long list of neglected double stars in the WDS – which explained why there were no measures of Fox 202 between 1909 and 1983.

As for the last (2003) measure listed in the WDS for Fox 202, the bibliographic information in the text file showed the source of those measures came from an unpublished manuscript connected with a 2003 project at Georgia State University. Given that the separation of 55.40” in that manuscript varies by over ten arc seconds from Fox and Tobal’s measurements, it’s quite likely a result of an error. Just to check a bit further, I turned to Vizier for the Aladin image of Fox 202 shown below and used Vizier’s measuring tools to come up with a separation of 45.22” and a position angle of 233.7 degrees, very close matches to Tobal’s 1983 data.

Click for a larger image.

Click for a larger image.

As I mentioned at the outset, we’re in a seldom-traveled and neglected part of the sky, which we’ll find is the case again with our next pair, Σ 2167.

This one will require some careful navigating even though it isn’t far (here’s our chart again). There are two ways to get there. First, move due west to a pair of faint stars, magnitude 8.65 HIP 85430 and 8.55 magnitude SAO 46712 (no HIP number).   The distance from Fox 202 to HIP 85430 is 40’, and from there it’s another 32’ southwest to Σ 2167. Because that pair of stars is faint and right at the limit of many finders, you might have better luck dropping back down to 7.35 magnitude HIP 85880 and then moving due west for a distance of 1° 25’ to reach Σ 2167.

Σ 2167            HIP: 85175   SAO: 46697
RA: 17h 24.4m   Dec: +49° 31’
Magnitudes: 8.12, 10.67
Separation:  20.8”
Position Angle: 208° (WDS 2010)
Distance: 843 Light Years (WDS)
Spectral Classification: “A” is F5

Another faint Struve pair (in the center of the view) surrounded by an interesting scattering of stars. The primary was white and the secondary was almost an averted vision object because of the 2.5 magnitudes of difference. (East & west reversed, click on the sketch for a much better view).

Another faint Struve pair (in the center of the view) surrounded by an interesting scattering of stars. The primary was white and the secondary was almost an averted vision object because of the 2.5 magnitudes of difference. (East & west reversed, click on the sketch for a much better view).

In our last tour, we ran into a Struve pair, Σ 2293, which had been labeled as rejected (“rej.”) in Burnham’s 1906 catalog, and that was again the case with this pair.

Burnham on STF 2167 in 1906

Lewis also skipped over it in his collection of Struve observations, so I went back to Struve’s 1827 catalog and found he had described the pair as having a separation of between 4” and 8” (see p. X of Lewis for a breakdown of Struve’s Roman numeral categories), which obviously doesn’t match Espin’s observation of 18.24” in 1900 or the WDS observation of 20.8” in 2010  . . . . .  which explains the “rej.” notation.

Curious as to whether any other observations might have existed between Struve’s in 1827 and Espin’s in 1900, I once again sent a request to Brian Mason at the WDS.  And again, when I opened the text file I was surprised at what I found:  not a single observation between 1827 and 1900.  But I did find a series of observations made relatively quickly following Espin’s, which I collected from various sources based on the bibliographical information in the WDS text file.   Among those were observations by Burnham in 1907 and Philip Fox in 1909. I also found a pair of observations from 1901 and 1902 by an Italian astronomer, A. Bemporad, which weren’t published until 1934, along with a 1919 observation by W.S. Franks.

Click for a larger view.

Click for a larger view.

There’s a steady increase in separation in those measurements as well as the later ones in the WDS text file up through the most recent 2010 data, which is reflected in the proper motion numbers for the Σ 2167 pair. The primary is listed with a proper motion of -022 +040, meaning it’s moving west at the rate of .022” per year and north .040” per year, while the secondary is practically sitting still with motions of +001 (.001” east/year) and -004 (.004” south/year).

Our last stop is Σ 2142, which is due west of Σ 2167. Start by moving a long degree (1° 15’) due west to 7.50 magnitude HIP 84530 (here’s that chart again). Then continue due west for another 50’ and you’ll arrive at Σ 2142.

Σ 2142            HIP: 84108   SAO: 46561
RA: 17h 11.7m    Dec: +49° 45’
Identifier            Magnitudes        Separation         Position Angle        WDS
STF 2142   AB:  6.18,   9.35             5.30”                   109°                2006
KUI 78       AC:  6.18, 14.70            28.10”                   107°                2003
Distance: 309 Light Years (Simbad)
Spectral Classification:  “A” is A5

You have to look closely to see the weak ninth magnitude secondary overshadowed by a white primary three magnitudes brighter. With the 18mm Radian I used for the sketch, I needed averted vision to see the secondary (mainly because of poor seeing), but could detect it easily with direct vision using a 14mm Radian (109x). (East & west reversed once more, click on the sketch to improve the view).

You have to look closely to see the weak ninth magnitude secondary overshadowed by a white primary three magnitudes brighter. With the 18mm Radian I used for the sketch, I needed averted vision to see the secondary (mainly because of poor seeing), but could detect it easily with direct vision using a 14mm Radian (109x). (East & west reversed once more, click on the sketch to improve the view).

There’s another double over at the east edge of the field of view, COU 1776.  Magnitudes on that one are 10.5 and 11.0 (although Simbad shows the primary at 9.91) with a separation of 0.4” and a PA of 276 degrees (WDS 2008). Again, just a slight bit out of my reach.

To get some perspective on the Σ 2142 pair, I went to Lewis’s book on Struve’s double stars, which listed observations from 1830 to 1905. I added additional observations in red — a 1902 observation by W. J. Hussey that I found in Burnham’s 1906 catalog and some WDS observations I pulled from archived WDS lists.

Lewis on STF 2142

As you can see, this pair of stars seems to be wobbling just a bit.  With the exception of Mädler’s 1843 observation, the position angle decreases steadily through 1905, but then from 1958 to 2006 it bounces back and forth. Meanwhile, the separation is inconsistent throughout the whole range of dates. Again, in a situation like this one, proper motion is the best clue as to what’s taking place.  The WDS shows proper motion for the primary at +018 +016 (.018”/year east, .016”/year north) and the secondary at +019 +019.   Simbad shows the secondary at +019 +020, but surprisingly doesn’t show any data for the secondary.  If the WDS data is correct for both primary and secondary, it would mean there’s no change taking place between the two stars.

Not finding any help there, I took a look at several photos of Σ 2142 in hopes of finding one I could measure, but the secondary was drowned out by the primary’s glare in all of them.  What I did find, though, was the 14.7 magnitude “C” component, KUI 78, which I hadn’t been able to see in my six inch refractor.  In fact, I initially mistook it for the secondary because its position angle is very close to that of the secondary (109° for “B”, 107° for “C”).

1955 POSSI photo, click to enlarge.

1955 POSSI photo, click to enlarge.

I’m not sure what to make of the inconsistent data on Σ 2142, but at a minimum it leaves one with the impression that for some reason it’s a difficult star to measure. Why that would be the case I couldn’t even begin to guess, but at any rate it fits in with the other odd characteristics of this short stretch of the sky we’ve just looked at – forlorn, neglected, and unpredictable.

Next time out we’ll head south to Sheliak, aka Beta (β )Lyrae, to see what stellar oddities are lurking there in the dark.

Clear skies until then!   :cool:

Click for an even larger view!

Click for an even larger view!

On the Hercules-Draco Border – South of Eltanin: HDS 2572, Σ 2277, OΣ 343, and Σ 2293

After my last session in Hercules with a rather difficult double, OΣ 344, I found myself rather taken with the surrounding scenery and decided to stay a while.   First, there was the allure offered by the chance to see what OΣ 344’s numerical predecessor, OΣ 343, offered, and north of it were two enticing Struve (Σ) delicacies waiting to be cornered in an eyepiece.  First, though, I decided to strike out east of OΣ 344 in search of a dim double with a strange prefix, HDS 2572.

But first, we better get oriented:

Cast your eye north of Hercules to Gamma Draconis, aka Eltanin, a second magnitude K5 (orange) beauty worth lingering over. It also happens to be a multiple star with six faint components buried in its glare, ranging in magnitude from 11.2 to 13.4, cataloged as Bu 633. One of S.W. Burnham’s devilish delights, we’ll save it for another night. (Stellarium screen image with labels added, click on the chart to enlarge it).

Cast your eye north of Hercules to Gamma Draconis, aka Eltanin, a second magnitude K5 (orange) beauty worth lingering over. It also happens to be a multiple star with six faint components buried in its glare, ranging in magnitude from 11.2 to 13.4, cataloged as Bu 633. One of S.W. Burnham’s devilish delights, we’ll save it for another night. (Stellarium screen image with labels added, click on the chart to enlarge it).

To get to our first star, HDS 2572, we’ll retrace the route we took last time out to reach OΣ 344. Move east and somewhat south for a distance of 1° 45’ to reach 6.3 magnitude HIP 88732. Another half degree leap directly southeast will take us across the Draco-Hercules border to 7.3 magnitude HIP 88975. Now switch to the southwest and hop a short degree (actually 48’) to 6.5 magnitude OΣ 344. Pause for breath and then leap a full degree east to our goal, 9.65 magnitude HDS 2572.   If you have trouble seeing it in your finder, you should be able to pick out the 8.77 magnitude light of SAO 47315 (this one doesn’t have an HIP number). (Stellarium screen image with labels added, click on the chart for a larger view).

To get to our first star, HDS 2572, we’ll retrace the route we took last time out to reach OΣ 344. Move east and somewhat south for a distance of 1° 45’ to reach 6.3 magnitude HIP 88732. Another half degree hop directly southeast will take us across the Draco-Hercules border to 7.3 magnitude HIP 88975. Now switch to the southwest and hop a short degree (actually 48’) to 6.5 magnitude OΣ 344. Pause for breath and then leap a full degree east to our goal, 9.65 magnitude HDS 2572. If you have trouble seeing it in your finder, you should be able to pick out the 8.77 magnitude light of SAO 47315 (this one doesn’t have an HIP number), or you could just land halfway between OΣ 344 and 6.39 magnitude HIP 89943. (Stellarium screen image with labels added, click on the chart for a larger view).

HDS 2572           HIP: 89299   SAO: 47320
RA: 18h 13.3m   Dec: +49° 44’
Magnitudes: 9.65, 10.49
Separation:  14.5”
Position Angle: 70° (WDS 2006)
Distance: 596 Light Years
Spectral Classifications: “A” is K0, “B” is G0

Delicate and dim describes this pair (trio?) rather well. I detected a very pale orange fragment of light trying to escape from the primary. (East & west reversed to match the SCT image, click on the sketch to get a much better look).

Delicate and dim describes this pair (trio?) rather well. I detected a very pale orange fragment of light trying to escape from the primary. (East & west reversed to match the SCT image, click on the sketch to get a much better look).

Note the star peeking out between the primary and secondary! Click to enlarge.

Note the star peeking out between the primary and secondary! Click to enlarge.

Dim though it may be, this is a very striking configuration of stars in a 9.25” SCT. But there are a couple of things about HDS 2572 that jumped out at me right away.

First, the primary and secondary are very similar in brightness. Simbad shows the primary with a visual magnitude of 10.0, which fits better with the relative magnitudes of the two stars.   A glance at the inverted image at the right also leads me to believe there’s less than a full magnitude of difference between the pair (source).

Second, there’s that third star (GSC 03533-0606) parked east of the secondary, which is what makes the configuration so attractive. It’s listed with a photographic magnitude of 13.51, although visually it’s somewhere between 12.5 and 13.0. Using the measuring capability of Sky Tools 3, I found it’s separated by 19” from the secondary at a position angle of 84 degrees. It could as easily be included as a third member of HDS 2572 as not, but the cold harsh stellar reality of the matter is the primary and secondary aren’t related anyway, as this Simbad chart shows:

 “A” and “B” seem intent on going their own way.  Click to enlarge.

“A” and “B” seem intent on going their own way. Click to enlarge.

And one last item: if you’ve been wondering what the exotic and rare HDS prefix stands for . . . . . well, it’s not that exotic and the name is really not that rare.   HDS stands for Hipparcos Double Star – and even though this one is number 2572, I’ve never run into the prefix before this.

On to other stellar pastures now. Let’s hop back to OΣ 344 now and head south for F.G.W. Struve territory (here’s our last chart again for reference). We’re in luck this time since we have a pointer to direct us. A glance 27’ south and slightly west of OΣ 344 will turn up the 7.39 magnitude orangish light of HIP 88602.   Follow the line formed by OΣ 344-HIP 88602 a full degree further southwest and you’ll find sixth magnitude Σ 2277 waiting for you, parked at the north end of a line of four stars of similar magnitude.

Σ 2277            HIP: 88415   SAO: 47173
RA: 18h 03.1m   Dec: +48° 28’
Magnitudes   AB: 6.28, 8.93   AC: 6.25, 10.19   BC: 8.93, 10.19
Separations  AB: 26.40”         AC: 99.70”          BC: 123.60”
Position Angles   AB: 130° (WDS 2011)   AC: 299° (WDS 2010)  BC: 299° (WDS 2003)
Distance: 526 Light Years (WDS)
Spectral Classifications: “A” is A1, “B” is K
Note: High Proper Motion for C, -006 +231  (.006” west/year, .231” north/year)
(PM for A is +021 +012 [east and north] and for B is -015 -010 [west and south])

The primary is a very definite white, but between the secondary’s relative faintness compared with the primary and its proximity to it, I didn’t see any trace of the orange which is normally present in a K class star. (East & west reversed to match the SCT view, click on the sketch to enlarge it).

The primary is a very definite white, but between the secondary’s relative faintness compared with the primary and its proximity to it, I didn’t see any trace of the orange which is normally present in a K class star. (East & west reversed to match the SCT view, click on the sketch to enlarge it).

SCStI photo, click to enlarge.

STScI photo, click to enlarge.

Again I noticed the relative magnitudes weren’t matching the data – “C” looked brighter to me than “B”, even though “B” was listed as being 1.26 magnitudes brighter. Checking the visual magnitudes in Simbad, I found the difference was about the same, even though the visual magnitudes themselves were slightly different: 8.83 for “B” and 10.08 for “C”. The glare from the primary, which is 2.65 magnitudes brighter than “B”, accounts for part of that impression, and I suspect “B”’s orange spectral class (orange is less visually intense than white) also has some effect. As the STScI photo above clearly shows, “B” is brighter than “C”, but not by much.

Click to enlarge.

Click to enlarge.

Another interesting aspect of these three stars is the high proper motion of “C”, which was added to the system in 1895. S. W. Burnham (see excerpt at right [source]) credits Glasenapp with some 1897 measures, but the WDS data show 1895 as the date of first measurement. Thomas Lewis (p. 525) also shows Glasenapp making measurements of AB in 1895. Notice that although there has been little change in separation of the AB pair, the position angle has changed quite a bit since the three measures shown by Burnham, apparently a result of the primary and secondary moving in opposite directions from each other.

The Simbad chart below illustrates that very clearly, as well as showing “C” is fleeing the sight rapidly. At any rate, it’s clear from their proper motions, none of the three stars are physically bound to each other.  (The proper motion numbers in the data above are from Simbad).

Click to enlarge.

Click to enlarge.

On to Σ 2293 now. With Σ 2277 centered in your finder (here’s the last chart again), look a long degree east (actual distance is 1° 7’) and you should see an eighth magnitude bundle of photons beaming from Σ 2293. For reference, 6.65 magnitude HIP 89143 can be seen 18′ east and slightly south of Σ 2293.

Σ 2293            HIP: 88999   SAO: 47273
RA: 18h 09.9m   Dec: +48° 24’
Magnitudes: 8.08, 10.34
Separation:  13.4”
Position Angle: 83° (WDS 2008)
Distance: 257.5 Light Years (Simbad)
Spectral Classification: “A” is G0

Just your basic primary-secondary pair. The primary appeared white to me, even though its G0 spectral class argues it should have some yellow present.   (East & west reversed once more, click on the sketch to improve the view).

Just your basic primary-secondary pair. The primary appeared white to me, even though its G0 spectral class argues it should have some yellow present. (East & west reversed once more, click on the sketch to improve the view).

There are two faint pairs in the field — one on the southeast side of the sketch, the other north and slightly east of the primary – neither of which are identified as doubles from what I can determine. The star labeled TDT 713 was just a bit beyond my reach with magnitudes of 10.85 and 10.90 and a separation of 0.5”, although on a night of steady seeing it ought to be possible to see the pair in a 9.25 inch SCT. (The TDT prefix stands for Tyco Double Star).

There was a surprise lurking for me when I checked Burnham’s 1906 catalog to see what data and notes he had on this pair:

Burnham on STF 2293 in 1906

First, it looks like Hussey (Hu) reversed the position angle – the measurement shown is from “B” to “A” (add 180 to the 83 degrees shown in the data above for 2008 to get 263°). And of course, the other was that rejRejected???  I immediately went to Lewis’s compilation (p. 530) of the senior Struve’s observations and found he skipped over it entirely.  I knew there was more here than met they eye at the eyepiece, so I sent off a request to Brian Mason at the USNO (WDS), hoping the data in the text file for Σ 2293 would shed some light here.

But Struve’s initial observation wasn’t included there, so I looked it up in his 1827 Catalogus novus stellarum duplicium, only to find it wasn’t much help. As you can see below, there is no separation or position angle shown, which is actually the case for all of the stars listed in that 1827 catalog.

Struve on STF 2293

Click to enlarge.

However, Struve used a classification system of Roman numerals similar to William Herschel to indicate separation, which can be seen in the column labeled “Description”.  Unfortunately, I’m not quite sure why he shows two Roman numerals in the listing for Σ 2293.  At any rate, neither is much help: the “III” refers to separations of 2” to 4”, and the “IV” refers to separations of 4” to 8” (see page X of Lewis’s book for that information), neither of which applies in the case of Σ 2293 . . . . . . . which I presume is the reason his listing for Σ 2293 was rejected.

Getting back to the text file Brian Mason sent me for Σ 2293, I found the first measure listed was dated 1901, but was unable to track that one down.   I had more luck with the second one shown, since it was the W.J. Hussey measure shown above in the excerpt from Burnham’s 1906 catalog.  As I scanned further down the list, I discovered Burnham had located Σ 2293 in 1907 (source) and measured it, followed by Eric Doolittle (source) in 1908 and T.E. Espin (source) in 1911.

Burnham-Doolittle-Espin on STF 2293So as of 1911 it would appear Σ 2293 had been solidly rescued by those three observers. But then it disappears from the record again — for a period of fifty-five years, from 1925 to 1980, there are no measures listed.  I’m sure there’s a story there, but I have no idea what it is — maybe a hint of sly stellar sleight of hand?

Whatever the case, it’s fortunate this pair was rescued from wherever it went since it’s actually a physically related pair, unlike our previous star, Σ 2277. You can tell that by looking at the proper motion numbers in Simbad, which for “A” are -028 +062 (.028” west/year, .062” north/year) and for “B” are -027 +060. Graphed they look like this:

Click to enlarge.

Click to enlarge.

Last on our list is OΣ 343, which lies south of and midway between Σ 2293 and Σ 2277 (last chart again). If you’re pacing off distances in the sky, it’s 52’ from Σ 2293 to OΣ 343, and 27’ from Σ 2277.

OΣ 343          HIP: 88555   SAO: 47200
RA: 18h 04.9m   Dec: +48° 08’
Magnitudes: 7.63, 10.51
Separation:  3.3”
Position Angle: 79° (WDS 2002)
Distance: 414 Light Years (Simbad)
Spectral Classification: A2

The primary was white and the secondary was barely a spark of light. I needed 175x (14mm Radian) to see it clearly on 6/23, but two nights earlier when I made the sketch it had been easy to see at 136x (18mm Radian).   (East & west reversed again, click on the sketch to get a much better look at the secondary).

The primary was white and the secondary was barely a spark of light. I needed 175x (14mm Radian) to see it clearly on 6/23, but two nights earlier when I made the sketch it had been easy to see at 136x (18mm Radian). (East & west reversed again, click on the sketch to get a much better look at the secondary).

I think it would be fair to classify this tight pair as training for its much more difficult numerical successor, OΣ 344, which we covered last time out. We’re dealing with 2.88 magnitudes of difference here between the primary and secondary and 3.3” of separation, compared to 3.84 magnitudes of difference and a full arc second less of separation on OΣ 344. For a visual observer, there’s an abyss of difference between those two scenarios, but even at that, OΣ 343 can be a difficult character when the seeing fails to cooperate.

The good news is these two stars are gradually moving further apart. Otto Struve measured the separation at 2.55” in 1846 when he discovered the pair, and as the excerpt from W. J. Hussey’s compilation shows below, the measures in the following years show a steady widening.

Hussey on STT 343

And that’s it for this part of Hercules south of Eltanin. Next time we’ll see what Herculean gems are lurking beneath the star that marks the southwest corner of Draco’s head, Rastaban, aka Beta (β) Draconis.

Clear Skies! :cool:

Wrestling on a Herculean Mat: A Tale of Two Close Encounters — OΣ 344 (with Σ 2290) and Zeta (ζ) Herculis

OK, it’s time to put away the low power eyepieces and aperture-challenged optical devices and get serious about prying into the diabolically difficult and totally torturous realm of high Delta doubles. Those would be doubles with magnitude differences of roughly two magnitudes or more. And to keep things manageable and sane, we’ll stay away from any pairs fainter than fifteenth magnitude. ;)

But in reality we don’t need to go anywhere near that faint – not that we ever could anyway – because the two stars we’re going to look at here are more than capable of making us yearn for less challenging targets such as Albireo or Mizar. In fact, keep a bottle of aspirin handy – you may need to subdue a headache caused by high-frequency stellar spinning-hopping-and-twitching.

We’re going to start way up high in the northeastern corner of Hercules with an enticingly innocent 6.47 magnitude star dubbed OΣ 344 by its discoverer, Otto Struve, and then re-dubbed STT 344 by the Washington Double Star Catalog (WDS).  If you didn’t know there was a tenth magnitude companion hovering near that 6.47 bundle of photons, you probably would skip right over it – which just goes to show there are times when ignorance can truly be bliss.

But since the fate of a double star addict is to be cursed with a surplus knowledge of numerical data, we’ve got no choice but to stop and take a peek.

Hang on tight.

Zeta (ζ) Herculis, the second star we’ll look at, is easily found at the southwest corner of the distinctive Hercules Keystone asterism. The star we’re in search of now, OΣ 344, is hiding two and a half degrees southeast of Gamma (γ) Draconis. Since it’s three and half magnitudes fainter than Zeta (ζ) Herculis, we’ll need another chart to locate it. (Stellarium screen image with labels added, click to enlarge).

Zeta (ζ) Herculis, the second star we’ll look at, is easily found at the southwest corner of the distinctive Hercules Keystone asterism. The star we’re in search of now, OΣ 344, is hiding two and a half degrees southeast of Gamma (γ) Draconis. Since it’s three and half magnitudes fainter than Zeta (ζ) Herculis, we’ll need another chart to locate it. (Stellarium screen image with labels added, click to enlarge).

We’ll start at second magnitude Gamma (γ) Draconis and move east and slightly south for a distance of 1° 45’, to 6.3 magnitude HIP 88732. Then we’ll cross the border into Hercules by making a half degree jump directly southeast to 7.3 magnitude HIP 88975 (also known as HU 674, a tight pair we’ll avoid since it’s separated by .52”).   Now hop just short of a degree (48’) southwest to our goal, 6.5 magnitude OΣ 344, which is at the north end of a faint, but distinctive, group of three seventh and eighth magnitudes stars. Be careful not to land on another similarly configured, but wider, group of four stars located another degree to the southwest.   I’ve labeled the northern member of that group, 6.2 magnitude HIP 88415 (also known as Σ 2277, which we’ll come back to in another post). (Stellarium screen image with labels added, click on the chart for a larger view).

We’ll start at second magnitude Gamma (γ) Draconis and move east and slightly south for a distance of 1° 45’, to 6.3 magnitude HIP 88732. Then we’ll cross the border into Hercules by making a half degree jump directly southeast to 7.3 magnitude HIP 88975 (also known as HU 674, a tight pair we’ll avoid since it’s separated by .52”). Now hop just short of a degree (48’) southwest to our goal, 6.5 magnitude OΣ 344, which is at the north end of a faint, but distinctive, group of three seventh and eighth magnitudes stars. Be careful not to land on another similarly configured, but wider, group of four stars located another degree to the southwest. I’ve labeled the northern member of that group, 6.2 magnitude HIP 88415 (also known as Σ 2277, which we’ll come back to in another post). (Stellarium screen image with labels added, click on the chart for a larger view).

OΣ 344 (STT 344)             HIP: 88754   SAO: 47233
RA: 18h 07.1m   Dec: +49° 43’
Magnitudes: 6.47, 10.31
Separation:  2.3”
Position Angle: 140° (WDS 2009)
Distance: 722 Light Years
Spectral Classification:  “A” is  A2

I was first made aware of the existence of OΣ 344 after wrestling two difficult high Delta pairs to a dubious draw in Ursa Major (namely Bu 1074 and Cou 1900) when Mark McPhee posted a comment about it – something like “If you’d like a taste of what Cou 1900 is supposed to offer, mosey over to STT 344 in Hercules – you won’t be disappointed.”  Now that’s like waving a dog-eared first edition copy of Burnham’s 1906 double star catalog in front of me, but I had to wait until seeing conditions aligned with the stars, so to speak.   It took most of a year, but I finally had my chance – and this is what things looked like on first approach:

As I said, very innocent looking – just another six-plus magnitude star beaming its white photons into a fairly sparse field. (East and west are reversed here to match the SCT view).

As I said, very innocent looking – just another six-plus magnitude star beaming its white photons into a fairly sparse field.  Note the location of ninth magnitude SAO 47230 — we’re going to need that later.  (East and west are reversed here to match the SCT view, click on the sketch to enlarge it).

So there I sat, parked permanently (at least it had begun to seem that way) in upper northeast Hercules, attempting to wrestle frantically wriggling white photons into a stationary image for long enough to visually grab that 10.31 magnitude secondary. Seeing conditions were OK – certainly not worth bowing to the sky gods for – but I had a hunch there was a chance.  The image in a 10mm Radian (245x) didn’t divulge anything, but since the frantic wriggle wasn’t high frequency yet, I reached for what is usually my ace-in-the-hole ocular, an old Celestron 7.5mm Plössl (327x) . . . . . and the wriggle not only advanced into high frequency territory, the image turned to mush. Suddenly I couldn’t buy a sharp focus with that eyepiece for all the Plössls on planet Earth.

Sometimes, though, there’s a different world lurking on the other side of that realm where visual images turn to mushy photons, so I reached for another dependable tool, a 6mm Astro-Tech Plössl. That eyepiece has always done an excellent job at controlling the glare in very glaring situations, such as this one.   And for who knows what reason, I was able to get its 408x image into focus – usually only briefly, but occasionally for several seconds at a time.

I sat patiently still, waiting and hoping for that magical secondarial sighting, while my tortured right eye grudgingly tolerated my obsession. After about fifteen minutes – I’m guessing since time becomes every bit as relative in this situation as Einstein predicted – I had an averted vision glimpse of something popping into view just inside the thick diffraction ring surrounding the primary.

Several times it leaped into sight and then slipped silently back into the primary’s high frequency twitch, and then re-appeared again.   After several of those teasing episodes, I grabbed the secondarial light with direct vision and held it for a couple of seconds:

Believe me, the image was nowhere near this stable.   (East & west reversed once again).

Believe me, the image was nowhere near this stable.  Click on the image to get a better view of the secondary. (East & west reversed once again).

Seeing conditions seemed to be improving slightly – either that, or my eyepiece eye and a secret compartment in my brain were getting better at cooperating with each other. At one point, I had the secondary in direct view for about ten seconds. It was a bit more than a puff of light – it had to be in order to be seen in the primary’s throbbing glare – but not quite what you would call a splendidly solid beam of light. At times there was almost a thinly transparent, surreal, quality to it.

But it was there – definitely, undeniably, unquestionably there – which was more than I had been able to say about the secondaries of Bu 1074 and Cou 1900 the year prior.

And as I sat there, mesmerized into a stellar stupor, I remembered another Herculean challenge – Zeta. But by the time I tore myself loose from Otto Struve’s 344th pair, the clouds began moving in, turning the sky into a featureless dark ocean. So I had to wait until the following night . . . . . . . and having wrestled unsuccessfully with Zeta numerous times the prior year, I reached for the 9.25 inch edge once again.

BUT – before you move your scope, we really should pan over to one of F.G.W. Struve’s nearby discoveries, Σ 2290, for a quick peek – it’s located a mere 18’ to the north. If you move OΣ 344 to the south edge of the field of view, Σ 2290 will come into view just slightly west of the north corner of the field. You can use 8.79 magnitude SAO 47230 to guide you in the correct direction.

Σ 2290         HIP: 88713   SAO: 30749
RA: 18h 06.6m   Dec: +50° 01’
Identifier                  Magnitudes          Separation        Position Angle        WDS
Cou 2276    Aa, Ab:  9.77, 10.00                0.30”                  13°                 1993
STF 2290         AB:  8.90, 11.20                3.90”                 352°                 2009
STF 2290         AC:  8.90, 12.70            178.00”                   69°                 2003
Distance: 2233 Light Years (Simbad)
Spectral Classification:  “A” is A5

The primary was a definite white, and the close-in eleventh magnitude secondary was easy to spot when the seeing cooperated and a real pain when it didn’t. The 12.70 magnitude “C” component, added to the system in 1880, is just a speck of light in the 9.25 inch SCT. You have to wonder why the 13th magnitude star one minute north of “C” wasn’t included at the same time.   (East & west reversed once more, click on the sketch for a much better version).

The primary was a definite white, and the close-in eleventh magnitude secondary was easy to spot when the seeing cooperated, and a real pain when it didn’t. The 12.70 magnitude “C” component, added to the system in 1880, is just a speck of light in the 9.25 inch SCT. You have to wonder why the 13th magnitude star one minute north of “C” wasn’t included at the same time. (East & west reversed once more, click on the sketch for a much better version).

Now that we have that one under our belts, we’ll move on to Zeta (ζ ) Herculis. If you’ve lost track of it, here’s the first chart once again.

Zeta (ζ) Herculis  (40 Her)  (Σ 2084)  (H I 36)
HIP: 81693   SAO: 65485
RA: 16h 41.3m   Dec: +31° 36’
Magnitudes: 2.95, 5.40
Separation:  1.186”
Position Angle: 145.5° (WDS 2014)
Distance: 35 Light Years
Spectral Classification: “A” is G0, “B” is G7
Note: Orbit and data can be seen here

I think it was Neil English, renowned guru of the long focus achromatic refractor, who first brought Zeta (ζ) Herculis to my attention — and here I was, attacking it with an SCT.   However, without giving too much away, after the evening with the SCT, I returned to the refractor fold with my six inch f/10 to get this wide field view of Zeta (ζ):

Again, a very sparse field, but enhanced marvelously by Zeta’s subtly hypnotizing gold/white glow that I find absolutely irresistible after two seasons of staring at it. (East and west reversed to match the refractor view).

Again, a very sparse field, but enhanced marvelously by Zeta’s subtly hypnotizing gold/white glow that I find absolutely irresistible after two seasons of staring at it. (East and west reversed to match the refractor view — click on the sketch to bring the gold glow to life).

To get back to the evening of June 23rd, I found the skies a couple of notches more cooperative, something close to a IV on this chart. I spent some time on other objects until close to midnight, which gave Zeta (ζ) plenty of time to get into position high in the sky and just west of the meridian. Once I located it and centered it in an 18mm Radian (136x), I went immediately to the 6mm Astro-Tech Plössl (408x) again. The image was more steady than the previous night, so it didn’t take long at all to realize the secondary was sitting out in the open, right at the outer edge of the first diffraction ring:

Apart from the welcome sight of the secondary, one of the things I quickly noticed was the pleasing gold/white photons characteristic of the low power view had been transformed into a thin, weak yellow.

Apart from the welcome sight of the secondary, one of the things I quickly noticed was the pleasing gold/white photons characteristic of the low power view had been transformed into a thin, weak yellow.  (East & west reversed, click on the sketch for a larger view).

I was amazed at how easy it was! I had tried and failed to split Zeta several times the previous year and here it was, just like that, on the first try. But now that I had the secondary in sight, I realized last year’s tantalizing teases were the real thing.  All those attempts had been under less than friendly seeing conditions, with so much jumping, whirling, spinning, and hopping that I could never be certain of what I saw.

When I returned to Zeta (ζ) a week later to get the wide field sketch with the 6 inch f/10 refractor, the seeing conditions were somewhere between the previous visit to Zeta (ζ) and the one to OΣ 344. I couldn’t resist the temptation to try again, so after I finished the 84x sketch, I reached for the 6mm AT Plössl (253x) once more to see what would happen. I had to look closely, but the secondary was definitely attempting to split off from the primary – what it needed was some help.

I grabbed a seldom-used 2.4x Dakin Barlow, slipped the 6mm AT Plössl into it, parked the whole thing in the diagonal, and then leaned over the unified pair and attempted to focus the blurred, vibrating image staring back at me. There’s one thing you just can’t miss when you blow up a yellowish 2.95 magnitude star to 608x – it’s dazzlingly bright. In fact, it seems to light up the whole field of view. With a very delicate touch on the two-speed focuser’s fine focus knob, I nudged the image toward what I hoped would be something resembling a focused star.

All the yellow-white light compressed into that diminutive five arc minute field was shimmering as though the star was about to erupt. Slowly, then suddenly, the image came into focus. I had to coax my eyepiece eye into reconnecting with the same secret compartment in my brain it had found on the night with OΣ 344, but after it re-established the connection, I could see through the glare to the secondary, sitting once more on the outer edge of the first diffraction ring with what looked like a mile of open space between it and the primary. OK – that’s a bit of an exaggeration caused by a temporary illusion and a very brief bout of insanity, but . . . . . . . . WOW! What a sight!

Double star nirvana! It seldom gets better than this! (East & west reversed once again).

Double star nirvana! It seldom gets better than this! (East & west reversed once again, click on the sketch to enlarge the gap between the primary and secondary).

William Herschel came up with a great phrase to describe the suddenly obvious distance between the primary and secondary at very high magnifications: “the distance is, as it were, laid open to the view.” You can almost see that thought materializing in his mind as he describes his experience with Zeta (ζ) on July 18th, 1782 (source, scroll down to the sixth title):

Notice those magnifications: 460x, 932x, and 811x! (The quote above is from the bottom of the same page as this observation).

Notice those magnifications: 460x, 932x, and 811x! (The quote above is from the bottom of the same page as this observation).

There’s nothing like the thrill of peering into the dazzle of magnified starlight and catching sight of a smaller secondary, very clear and very distinct, with black space between it and the primary, each of them vibrating, spinning, hopping, and leaping in unison – and around both of them, a diffraction ring shimmering so rapidly it appears to be spinning. It’s an electrical thrill that causes every quark in you to quiver (and probably quite a few outside you), and reminds you the sketch is only a snapshot of an experience quite literally out of this world.

Gotta go grab a small glass of something strong to calm the optic nerves now . . . . . . .

Clear (and stable) Skies!   :cool:  (Next time, back to northern Hercules again).

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