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

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“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! 😎

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13 Responses

  1. John,

    I thought that the position angle was always from the stated star, so here A to B (Or C to D or whatever), so the tangled issue of which is fainter is neither here nor there. In fact off-hand I can think of several stars where A is fainter than B (not being able to name them right now!).

    Peter

    • Hi Peter,

      A quote from p. 2 of Bob Argyle’s book, Observing and Measuring Double Stars:

      “The separation is one of two quantities needed to fully describe the relative position of double stars, the other being the position angle. With the brighter of the two stars being taken as the origin, the separation is defined as the angular distance in arcseconds between the two stars and the position angle is the bearing of the fainter star from the brighter in degrees with north being taken as 0 degrees, east is 90 degrees, and so on.”

      I’ve come a across a few multiple stars (meaning more than two components) in which one component was brighter than the primary — probably because that component was added at a later date by someone — but never a double star consisting of only two components in which the basic rule of measuring from the brighter to the fainter star was ignored. A look through the WDS listings will confirm that.

      Having an accepted practice for measuring position angle and sticking to it aids greatly in identification.

      John

      • Although it is very rare, there are cases where the B star is brighter than the A star. From my own observations, S 781 and S 437 don’t count as they are AB-D and AB-C respectively, but STFA 60 and AG 308 are clear cut examples where the B star is brighter than the A star and I assume that the position angle is taken from A not B and I recall this being the case with AG 308 where the difference is obvious visually.

  2. Hi John!
    Another Herculean effort to bring this part of the sky to life. I will be looking at Epsilon Lyrae in a whole new way. Each time I strain my refractor to the zenith, it gives me much pause to consider the purchase of a Dob.

    Jumping into the discussion about how one is to measure PA, I suspect much has to do with the assumption, by most, that the brighter star is always the primary. Simple logic suggests this, and I believe most of the early recording of double stars followed this convention. I guess confusion only serves to keep us on our collective toes.

    Cheers, Chris.

    • Thanks for the comments, Chris — there were a lot of hours invested in that post!

      Getting back to Peter’s reply, position angles have been measured from the brighter to the fainter star since at least the days of William Herschel, if not before. So when we come across a system in which that isn’t the case, normally there’s an explanation.

      I looked further into all four of the stars Peter mentioned to see what would turn up. S 781 and S 437 both really intrigued me since I’ve never come across one of James South’s discoveries which didn’t adhere to the normal practice for position angles.

      S 781 – South’s original PA for the AB pair was 82° 58 np, which is equivalent to present day 352° 58’ (see page 277 of South’s Catalog, Vol. 116 of Philosophical Transactions). That value is 180 degrees opposite of the value Burnham assigned to it in his 1900 catalog (General Catalogue of Double Stars Discovered from 1871 to 1899), p. 225. That was a result of a decision by someone (probably by Burnham) to re-designate the fainter of South’s pair “A” when Burnham added the 9.40 magnitude companion (today’s “B”) in 1875 and the 14.01 companion in 1877 (today’s “C”), resulting in South’s “A” being re-designated as “D”.

      S 437 – We see the same thing here. South’s original 1832 PA was 29° 43’ sf, which is present day 119° 43’ (see page 43 of South’s 1826 catalog). Again, that’s 180 degrees opposite the value Burnham listed for it in his 1900 Catalog referred to above, p. 42. Burnham added two components in 1878: one was a 9.39 magnitude component (today’s “B”) to what was originally South’s secondary, plus a 12.80 magnitude component (today’s “D”) to what was originally South’s primary. The result was South’s secondary (“B”) became Burnham’s (and the present day) “A”, and South’s primary became Burnham’s (and present day) “C”.

      STFA 60 – I have yet to find a source for Struve’s first appendix, so I can’t get to his original observation of this pair. From looking at the present day data on it, once again components have been added to Struve’s original pair. A magnitude 10.25 component was designated “C” in 1901, and a 12.76 magnitude component was designated “D” in 1910. Also, the magnitudes of Struve’s original pair are very close, 7.46 and 7.28, which would have made it difficult to tell which of the two stars was the brighter, which is confirmed by the Aladin photo in Stelladoppie .

      AG 308 – Again, I can’t find the original source, which is the Astronomische Gesellschaft Katalog. This is a primary-secondary pair (no other components), and the magnitudes are close (7.18 and 6.55), but not so close they should cause confusion.

      I sent a request to Brian Mason at the WDS last night for the text files on STFA 60 and AG 308, hoping I would have them this morning for this message, but haven’t received them yet. I’ll add a comment here when I get them.

      As I’ve already mentioned, when the normal convention for position angles isn’t adhered to, there’s usually a reason. I can’t imagine why the normal practice would have been reversed in the case of AG 308 since the data in the AGK followed that practice, so it will be interesting to see what’s in the WDS text file.

      John

  3. Hi John,

    Many thanks for all your hard work on these four, especially the South stars which tell a twisted tale (almost literally). I will be very interested to see what comes back from Brian Mason. It must be possible amongst all the thousands of double stars that the original A dims for some reason or (perhaps more likely) the B brightens up a little since the original sighting. As Chris has said, double stars are rarely straight-forward!

    Best wishes,

    Peter

    • On the request for the WDS text files for AG 308 and STFA 60, I’m still waiting. Sent a second request today to Brian, so hopefully I’ll have something in the next day or two. He could be on vacation or out of town at a conference.

      John

      • OK, I have one out of two text files now! As it turned out, Brian was out of town, but he only sent me the file for AG 308 this morning. I’ve asked again for STFA 60, so I should have it tomorrow — it’ll be a few days before I get back to the computer, though.

        As for AG 308, we have a mixed bag of conflicting information. Actually, with regard to the original 1896 observation, we have NO information on magnitudes. In fact, the first published magnitudes for the pair is dated 1980! And from there, it gets even more strange. Below are the dates, the magnitudes, and the sources (the edit program for this screen doesn’t seem to want to include my spacing to separate the values, so you’ll have to look closely):

        1980.00: 6.5, 6.7 OAG General Catalog
        1991.25: 7.21, 6.58 Hipparcos
        1991.25 7.05, 6.57 Hipparcos
        1991.64: 7.18, 6.55 Tyco
        1991:64: 8.60, 6.54 Tyco
        1999.93 4.98, 6.48 2Mass
        1999.93 4.58, 6.55 2 Mass
        1999.93 4.27, 6.54 2 Mass
        2002.76 8.08, 8.06 UCAC
        2010.00 7.49, 7.72 APASS
        2010.00 8.59, 8.61 APASS
        2010.00 8.97, 8.51 APASS

        Rather puzzling is an understatement. The list starts off with the primary brighter than the secondary in 1980, they reverse in 1991 with the Hipparcos and Tyco Photometry, reverse again in 1999 with the 2Mass data, are evenly matched in 2002, and then flop back and forth in the AAVSO’s All Sky Photometry (APASS).

        I’ve checked Simbad and there is no AAVSO variable designation for either of the stars, so even though it looks like either or both stars could be variable, AAVSO doesn’t list them.

        As for the the multiple measures in 1991, 1999, and 2010, I would guess they were made at different wavelengths, but I don’t see any explanatory codes in the file.

        When I referred to binoculars and fifteenth magnitude galxies in the post above, I was only joking . . . . . . but I just might reconsider.

        John

  4. Really hate to mention it, but while recording my recent observations, I have come across another example, namely GRF 15 in Cygnus, A is 7.4 and 7.1. Thanks again for your efforts, it is very interesting.

    Peter

    • Hi Peter,

      Thanks — I think! Not sure when I’ll get to that one.

      Brian surprised me and sent the text file for STFA 60 this afternoon. It shows Struve estimated the magnitudes at 6.4 (primary) and 6.5 (secondary) in 1835. The magnitudes weren’t estimated or measured again until 1913, when Franks reversed them, 6.5 and 6.4.

      After that the next time the magnitudes were measured was in 1980, when the OAG put them at 7.3 and 7.3. In 1991 Hipparcos put them at 7.52 and 7.35, then reversed them again on the same date (1991.25), coming up with 7.20 and 7.36 — more than likely the measurements were made at different wavelengths. That same year, Tyco put them at 7.46 and 7.28, and 8.57 and 8.37.

      In 1996 the 2Mass survey came up with three values: 5.59 and 5.53, 5.12 and 5.14, and 5.04 and 5.06. In 2003 the UCAC survey placed them at 8.41 and 8.33, followed by APASS in 2010 with 7.46 and 7.29, and 8.58 and 8.36.

      And the most recent measure in 2012, 7.46 and 7.28, comes from last issue of the JDSO (July 2104, p. 174).

      Kind of looks like they’re too close to call!

      John

      • Hi John!
        I am a bit stunned by the data on AG 308. I have never requested this kind of data from Brian Mason before. Having done it on a number of occasions, have you ever seen this kind of “all over the map” data for a system before? It sure begs the question…”what Can we believe?” As I continue to build my image catalogue, I am continually running into magnitude data that looks suspect,,,most recently, J 476 in Aquila…WDS provides magnitudes of 9.5 and 9.7 while my image clearly shows the magnitude is more likely in the 11.5 range for both components. I guess, by us asking the questions, the data can only improve.

        Cheers, Chris.

  5. More on HJ 1341:

    I’ve been back to look at this pair three times in the last month and came away with an interesting observation. During the first two observations, the seeing was poor and I had a tough time even separating the two stars with my six inch f/10 refractor. They were wavering between a single smudge and for very brief periods, two distinct stars. But, when I could see both stars, they looked to be of the same magnitude.

    The third time, which was actually a night of sub-arcsecond seeing, a very rare occurrence around these parts, the star both John Herschel and I saw as the faintest was once again the fainter of the pair — not by much, mind you, but just enough that it was obvious.

    So it seems the poor seeing resulted in a strange kind of visual distortion or illusion, which is something I’ve never run up against before. I’ll file that away in my memory banks and keep an observational eye out for it in the future on some other duplicitous star.

    John

    • Hi Chris,

      On AG 308, no, I’ve never seen magnitude data bounce back and forth as frequently as it does on that star. I wouldn’t even begin to hazard a guess as to the cause, especially since the AAVSO doesn’t list either component as variable in magnitude.

      It used to really surprise me when I ran into obvious errors in the data, whether in the WDS or elsewhere. But I’ve come to the realization there are a lot of errors lurking in the double star data (and you’ll also find a surprising number of errors in the literature on galaxies). So when you come across something questionable, Brian and Bill at the USNO/WDS are the people to consult. They’re well aware there are errors in the data, but these databases are huge and full of all kinds of measures, so cleaning them up takes a lot eyes and effort.

      As to why the errors arise, anyone who has labored into the early morning hours at a telescope soon realizes how easy it is to make mistakes. Numbers get transposed, data gets written down in the wrong place or lost, a note that seemed crystal clear when it was written can be as clear as mud a day later, etc. I try to work slowly and methodically when I get bleary eyed, and am constantly double-checking myself, but stuff still happens.

      I got a kick out of a comment Bill Hartkopf included at the end of a message he sent me when we were discussing the non-existent fifth star in Nu Coronae Borealis: “So many stars, so many errors, however . . . . . . ”

      Prost!

      John

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