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Problems of a Different Magnitude in Lacerta: 8 Lacertae (STF 2922/A1459) and ROE 47

It had been a long while since I last took a stroll through Lacerta, so I had to grab my well-worn copy of Sky and Telescope’s Pocket Sky Atlas and relocate the constellation’s dim outline between Cygnus and Cepheus.   Lacerta is not one of those constellations that draws attention, which is unfortunate since the Milky Way runs through about 90% of its stellar real estate – meaning it has more than its share of double stars and open clusters. I was back to check on the Lacertan lizard once again because of a question about the magnitude of one of the components of 8 Lacertae, which in keeping with Lacerta’s rich stellar tradition, also has more than its share of stellar companions.   And as long as I was there, I decided to poke around and see what else I could see, which led to a magnitude of additional questions.

Even though it’s the first part of December as I write this, from my forty-five degree latitude Lacerta is almost directly overhead at 7 PM, parked in a holding position between Cygnus, Andromeda, and Pegasus, and Cepheus.

Stellarium screen image with labels added, click to enlarge.

Stellarium screen image with labels added, click to enlarge.

A line drawn from Beta (β) Cephei through Zeta (ζ) Cephei will actually lead you directly to 8 Lacertae:

You can also draw a line from Delta (δ) Cygni (just out of sight at the upper right of the chart) through Deneb, which will just miss the southern edge of 8 Lacerate. (Stellarium screen image with labels added, click to enlarge).

You can also draw a line from Delta (δ) Cygni (just out of sight at the upper right of the chart) through Deneb, which will just miss the southern edge of 8 Lacerate. (Stellarium screen image with labels added, click to enlarge).

But because Lacerta is a dim constellation . . . . . .

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

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

. . . . . . you might find it easier to aim an 8×50 or 9×50 finder at 4.5 magnitude 6 Lacertae, move northeast a few degrees to 4.5 magnitude 11 Lacertae, and then drop southeast to 5.1 magnitude 13 Lacerate, using 5.0 magnitude 15 Lacertae as a reference point, and then move south to 5.3 magnitude 12 and 4.9 magnitude 10 Lacertae, which form a triangle with sixth magnitude 8 Lacertae parked in the west corner.   That way you’ll be sure to land on the right star at least.   There should be little chance of confusing 8 Lac with another star since “A”, “B”, and “E” are bright and very obvious:

8 Lacertae  (AB is H IV 86)      HIP: 111546   SAO: 72509
RA: 22h 35.9m   Dec: +39° 38

Identifier      Magnitudes      Separation    PA   WDS
STF 2922 AB:      5.66,  6.29          22.40″   185°   2014
A 1469 AC:      5.66, 10.38          48.90″   168°   2014
A 1469 AD:      5.66,   9.09          81.60″   144°   2014
A 1469 AE:      5.66,   7.25        337.80″   239°   2011
DAL 28 AG:      5.66, 14.08          78.60″   194°   2012
COM 8 BF:      6.29, 10.97         127.60″   175°   2012
A 1469 CH:    10.38, 14.60            1.40″   254°   1932
A 1469 DI:      9.08, 13.30          10.10″   227°   2012
DAL 28 GJ:    14.08, 12.99            6.10″    78°   2009

Distance:  “A” is 2160 Light Years; “E” is 428 LY (Simbad)
Spectral Classifications:  “A” and “B” are B2, “D” is A0, “E” is F0
Notes: Mag of I changed from 11.0 to 13.3 as of 10-29-2015
Magnitudes of GJ are reversed in WDS, should be 12.99 and 14.08

In a mid-October email from Mike Hyrczyk via Chris Thuemen, Mike mentioned he had looked at 8 Lacertae and found the “I” component wasn’t visible in his six inch refractor. At the time, it was listed in the WDS at a magnitude of 11.0, normally well within reach of a six inch scope. That evening, I pointed my six inch f/10 refractor at the complex star and, at 152x, confirmed Mike’s observation. I tried higher magnifications – 253x, 365x, and 380x – and may have had a brief glimpse of the fickle star, but there was no doubt it was fainter than the WDS’s 11.0 magnitude. Chris used a 9.25 inch SCT the following night and basically had the same experience, although he may have detected an elongation in the DI pair. Chris also noticed the magnitudes of the GJ pair were reversed in the WDS, which hasn’t been corrected as of this writing.

Given the 10.10” separation listed for the DI pair, experience told me that a magnitude of 13.0 was about the brightest “I” could be, if in fact I had actually seen it with my six inch refractor in the combined AB glare. A check of photometry records in the UCAC4 catalog showed magnitudes of 13.828 (f.mag) and 13.598 (J and K converted to visual), which were too faint for me to have had a glimpse of the star. I sent what information I had to Bill Hartkopf at the USNO/WDS, who consulted additional photometry records, arriving at a magnitude of 13.30 for “I”.

So — after that long introduction, it’s about time we took a look:

“A”, “B”, and “E” are the stars that catch your eye on first view, all of which are white, followed by “C” and “D”. You have to look a bit closer to get your first glimpse of “F”. The missing “I” component is both too faint and too close to “D” to be seen, as discussed above. There are two more faint pairs to the south of 8 Lac, neither of which are not cataloged in the WDS as double stars. (East & west reversed, click on the sketch for a better view).

“A”, “B”, and “E” are the stars that catch your eye on first view, all of which are white, followed by “C” and “D”. You have to look a bit closer to get your first glimpse of “F”. The missing “I” component is both too faint and too close to “D” to be seen here. There are two more faint pairs to the south of 8 Lac, neither of which are cataloged in the WDS as double stars. (East & west reversed, click on the sketch for a better view).

There’s also an excellent photo and discussion of the 8 Lacertae complex on page 52 of the November issue of Sky and Telescope. Sue French was unable to see “I” with a 10 inch reflector, but found a fifteen inch scope brought it into view, which supports the WDS magnitude change to 13.30.   Sue also noticed the error in the WDS listing for the GJ pair.

8 Lacertae has an interesting history. Sir William Herschel was the first to record it for posterity, cataloging the AB pair as H IV 86 in 1782 (source, sixth title from the top):

Wm. Herschel on 8 Lac

His 84° 30’ south preceding works out to a present day figure of 185° 30’, which is a good match with the current WDS figure, but his separation of 17” 14’” puts the AB pair five arc seconds closer than the WDS data. He describes six stars, which probably correspond to the A through F pairs, although his description of their relative magnitudes is difficult to follow. The Latin phrase at the top of his catalog entry translates as “In the middle of the tail”, which seems to indicate a slightly different configuration for Lacerta than what I show above in the first chart.

Click to enlarge the image.

Click to enlarge the image.

Sirs John Herschel and James South made two observations of 8 Lacertae in September of 1823, which are shown at the right (source, last title on page).  Their measures of AB, which are summarized near the bottom of the page, are in line with the current WDS data, as are their measures of the AD pair (145° 15’, 82.52”, which they refer to as AC).   They seem to have entirely missed the closer 10.38 magnitude star now referred to as “C”.

At the bottom of that same page, they refer to an erroneous measure of the AB pair made by Piazzi in 1800 (212° 58’ and 19.072”). Admiral W.H. Smyth also refers to that error on pp. 519-520 of his Bedford Catalog, as well as William Herschel’s 1782 PA error. Relying on his distinctive pre-Victorian vocabulary to make the point, he wrote: “Here the anomalies are palpably owing to error, and the fixity of the objects appears unquestionable.”

The Admiral was irrefutably correct in regard to the “unquestionable fixity” of the objects.   Given the 2160 light year distance of “A”, little proper motion is exactly what would be expected.   Simbad doesn’t provide a distance for “B”, but it does show “E” to be at 428 light years, which is also far enough away that minimal proper motion would be the norm. I checked the most recent PM data available, which comes from the USNO’s URAT1 catalog, and it confirms the minimal motion for each of the stars:

8 Lac PM Data

Aladin image with labels and data added, click to make the text more legible.

“E” shows the most motion, which again is to be expected since it’s four times closer to us than “A”.   There are no parallaxes available in Simbad on the other components of the system, but judging by their slight motion, they may well be about the same distance as “A”. And at those distance, it’s impossible to come to any conclusion on shared physical motion based on the PM numbers.

Before heading out into the night air to look at 8 Lacertae, I used Sky Tools 3 to take a quick look around the neighborhood for other interesting stars, and quickly found an intriguing multiple star, ROE 47, located just 41’ to the west (here’s our third chart again).   So give your scope a careful nudge in that direction and you’ll be greeted by a sixth magnitude star with several faint companions.

ROE 47        HIP: 111259   SAO: 72446
RA: 22h 32.4m   Dec: +39° 47’

Identifier    Magnitudes    Separation    PA   WDS
ROE 47 AB:    5.90, 11.46        42.90″   155°   2012
ROE 47 AC:    5.90, 12.40        33.50″   341°   2012
ROE 47 AD:    5.90, 12.20      103.70″   216°   2010
FYM 109 AF:    5.90, 14.11        22.00″   106°   2012
ROE 47 DE:  12.20, 12.30          6.60″   175°   2012

Distance: 684 Light Years
Spectral Classification:  “A” is A6
Notes: Mag of C changed from 10.2 to 12.4 as of 10-29-2015
Mag of D changed from 11.36 to 12.2 as of 10-29-2015
Mag of E changed from 9.90 to 12.3 as of 10-29-2015

This one had what you might call a magnitude of problems, but before wrestling with that issue, let’s take a look:

 “A” was very white; “C” was very faint and mainly an averted vision apparition; “B” was distinct; and “D”, which was just a bit easier to see than “C”, was marginally duplicitous at 152x, but it cooperatively separated at 253x with a 6mm Astro-Tech/Sterling Plössl, as shown in the insert below the insert at the right. (East and west reversed once more, click on the sketch to improve the view considerably).

“A” was very white; “C” was very faint and mainly an averted vision apparition; “B” was distinct; and “D”, which was just a bit easier to see than “C”, was marginally duplicitous at 152x, but it cooperatively separated at 253x with a 6mm Astro-Tech/Sterling Plössl, as shown in the insert below the insert at the right. (East and west reversed once more, click on the sketch to improve the view considerably).

It didn’t take but a few seconds to realize that some of the fainter components I was looking at were fainter than the WDS data said they were. As the “C” component flickered in and out of view, I could see it was clearly fainter than the 10.2 magnitude then listed for it in the WDS. There was also something clearly amiss with “D”, which wavered between direct vision and averted vision, meaning it was also fainter than the WDS’s 11.36. And “E”, which was listed at a magnitude of 9.9, was not the conspicuous speck of light it should have been – in fact, it should have been over-powering “D”.   After I separated the DE pair at 253x, it was clear they were both about the same magnitude – so 9.90 was nowhere close to being correct. Chris Thuemen also looked at ROE 47 and basically came to similar conclusions.

There’s a huge amount of photometric data available in both the NOMAD-1 and the UCAC4 catalogs, so I turned to both of those to see what I could find.   Looking at “C”, I found data pointing to a magnitude of 12.3. In the case of the DE pair, the UCAC4 Vmags, which are normally very dependable in this range, showed 11.358 for both stars, which seemed too bright to me.   The UCAC4 f.mag and the J & K visual approximations pointed toward a magnitude of 11.9 to 12.0, which struck me as being closer to what I had seen.

ROE 47 Data Mirror Image

Click to enlarge and make the data more legible.

I sent off what I had to Bill Hartkopf at the USNO/WDS, who used additional data to make the changes I’ve listed at the bottom of the ROE 47 data above. Incidentally, Bill is always quick to say he appreciates these observations very much. With the WDS data base approaching something like 130,000 stars, the only way these kinds of errors get corrected is when visual observers note the discrepancies and report them to the WDS.

Click to enlarge the image.

Click to enlarge the image.

Digging into the history of ROE 47, it appears the AB and AD pairs were discovered in 1895 by E.D. Roe, Jr., a British amateur astronomer, who used a six inch refractor. He added the “C” and “E” components in 1910, as shown in the excerpt at the right from a 1911 issue of the Astronomische Nachrichten.

I couldn’t find any biographical material on E.D. Roe, but it appears he must have had an astronomically dry sense of humor.   If you look at the top left hand corner of the image above, you’ll see he used the Greek symbol “ρ” as an identifier, which in Greek is pronounced rho, as in Roe.  Obviously he liked a good laugh.

Next trip – who knows. The winter rains are here and the few clear skies I’ve seen have had more dancing and twinkling stars than an out of control strobe light at an all-night dance party, meaning atrocious seeing, which is not usual for this time of the year. As soon as the weather cooperates (raining hard now with 60mph gusts of wind), I’ll see what I can find to grace the pages of this blog.

Until then, Clear and Cooperative Skies!   😎

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9 Responses

  1. As always John a very good article . I enjoy the history behind the observations . Jewels in little Lacerta !!
    mike hyrczyk

  2. Thanks to you and Chris for letting me know about the magnitude problem with 8 Lacertae. That led to ROE 47, which altogether made for a very productive session!

    John

    • when can I pickup the new book John ?

      • I found I just didn’t have the time necessary to devote to the book, Mike, so I had to give it up. Too many other things competing for my time that were more important at this point.

        John

  3. I understand completely my friend .
    mike

  4. Nice work as usual, John. I’d like to observe these next fall when they come back around.
    Working on anything new these days. I’ve been fortunate to make it to the summit a little more often as of late.

  5. Hi Steve,

    Observing weather this past winter was virtually hopeless, so I’ve been busy with several JDSO projects.

    Had hopes of getting some sketching done last night on two tight pairs in Gemini, but the seeing was too poor to split either of them. Take a look at STF 1037 with your 9.25″ inch SCT if you get a chance. Magnitudes are 7.24 and 7.27 with a 2016 separation of 0.921″ at a PA of 305 degrees. I was able to split that one about this time last year with both the six inch f/10 refractor and my 9.25″ SCT. The equal magnitudes of the primary and secondary give you a decent chance when the seeing is at least average.

    John

  6. Right, John. I have a wide view of the Pacific from the Goes West WX satellite and its been kinda junky along the NW coast of the US.
    I’ll take a gander at STF 1037. Is it one you’re studying for a JDSO paper? The WX here has been pretty good as of this past couple of months. I’ve been getting to the summit almost once a week. Just lately we’ve had some tough tropical depressions. So, tonight, instead of going up to observe I attended an AstroTalk at the IfA. As you know, I’ve been working on the AstroLeague Sketching Program List. There’s 114 objects, and I’ve tackled about 72 so far. Its a lot of work and has gotten me into some pretty deep sky stuff; good for the C925. I’ve also been uploading some of my sketches on Cloudy Nights as “Mauigazer.” Most of them are on the D.S.I.P. site. More people seem to see the sketches on C.N. – they display a “hits” count. Many amateurs on the Double Star Forum, as you no doubt know, refer to Star Splitters and your excellent reports/research. Keep up the great work. I look forward to your next post.

    • I came across STF 1037 while I was working on an STT project for the JDSO (here) with Wilfried Knapp and Steve Smith.

      I was actually looking for STT 166 (the C component of STF 1037-STT 166), which we found to be a few tenths of a magnitude fainter than the value listed in the WDS at the time. There’s an image of the STF 1037-STT 166 system on the last page of the article.

      Had no problem splitting STT 1037 at the time — knew I should have made a detailed sketch but was pressed by time to move onto other things.

      John

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