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STF 3012 and 3013 in Pegasus

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#1 John Fitzgerald

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Posted 08 October 2019 - 10:18 PM

This is a double-double.  STF 3012: m1=9.5, m2=9.8, sep 2.9" at 190 deg.

STF 3013 is 53 seconds away and m1=8.5, m2=10.2, sep 3.2" at 277 deg.

 

It's a very interesting looking formation in my 6" apo at 243x.

 

According to the WDS catalog, this is likely a physical system of four stars, with a great separation between the two pairs.

This four star system is about 249 ly away.


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#2 R Botero

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Posted 09 October 2019 - 02:02 AM

John
Thank you for your post. I am yet to observe either of these.
Roberto

#3 chrysalis

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Posted 09 October 2019 - 03:36 PM

STF3012:

 

J2000 RA:  23h27m33.10s   DE:+16°37'22.0"
Date  RA:  23h28m32.80s   DE:+16°43'54.4"

 

STF3013:

 

J2000 RA:  23h27m36.40s   DE:+16°37'44.0"
Date  RA:  23h28m36.10s   DE:+16°44'16.4"


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#4 fred1871

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Posted 09 October 2019 - 08:58 PM

These two Struve pairs make a rather fine combination as a double-double. I first came across them in the 1990s, at a time when I had frequent access to a 7-inch refractor (one of Roland Christen's earlier apochromats). At a mere 90x on the 7-inch on a night of good seeing I recorded both as neat little pairs, obvious and easy. Later, with a 5.5-inch achro I could see both pairs as separated at 114x but only just showing; with less light it needed more magnification for a good view... 133x was better, and 200x showed them nicely. A good combination. I'll try them again, now that Pegasus is back, with a bit more aperture, 8 or 9-inch cat.


Edited by fred1871, 09 October 2019 - 08:59 PM.


#5 rugby

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Posted 09 October 2019 - 10:35 PM

I enjoyed the contrast between these pairs. In the 120 both were tight but obvious at 81x. A bright moon didnt help locating this target. If interested, try the neighbouring pairs 3056 and 3050 north of alpha And. 



#6 dmdouglass

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Posted 10 October 2019 - 11:21 PM

Interesting reading. I decided to take a look tonight. All of my "observing" is with a camera. Then i study the results.  And i think on this one, we may have a discussion here...

 

Here is the close up crop...  and i have marked what i believe are the AB C and D stars...

North is Up, and East is to the left.  

 

[Edit:  Oops... re-doing. My original was marked incorrectly.]

[Edit:  Here is image with no markings.  I am going to do some measurements of angles and distances tomorrow and will then post an update...}

 

No Markings.png

 

And here are the Stelle Doppie, and the WDS. The larger picture of these combos is known as WDS-23276-1638. And that object then contains STF-3012 and 3013.

 

STF 3012 3013.png

 

WDS 23276_1638  STF3012 3013.png

 

 

Interestingly, These two STF  objects seem to "share a star or two..."

 

I believe the "D" star (much fainter) is just to the right of the "C" star, and above the "AB" pair.

Could be wrong....  But the angles and all do seem to line up.

 

It will be interesting to hear what others may think...  


Edited by dmdouglass, 11 October 2019 - 12:58 AM.

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#7 ssmith

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Posted 11 October 2019 - 11:51 AM

Hi David -

 

Nice photo Dave but I believe it only shows the unresolved AB & CD components.

 

This is truly an incestuous system STF 3012, STF 3013 & DOB 18 all commingled.  This may be  a perfect candidate for John Nanson to untangle the historical context. 

 

Here is a ALADIN Plot showing the GAIA data which seems to confirm the Physicality of all four stars.

 

STF 3012&3013 Gaia2.jpg


Edited by ssmith, 11 October 2019 - 11:52 AM.

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#8 dmdouglass

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Posted 11 October 2019 - 12:12 PM

Howdy Steve, and we agree !

Here is my analysis....

.

STF 3012 3013 Measured.png

 

My main "problem" is that i used the wrong Telescope and Camera.  I have two (2), mounted side-by-side. Normally, for doubles, i would use the Edge HD-8" with the SBig 8300, which will give me 1.1 ArcSec/Pixel resolution (Bin 2x2). But in this case, i was using my 80mm, and the ZWO ASI183 Pro, which gives me 2.07 ArcSec/Pixel, making it very difficult to resolve for close pairs.  My error !

 

I was able to ID 3 of the four stars, but was unable to determine an ID for the "D" star.



#9 dmdouglass

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Posted 11 October 2019 - 12:19 PM

This is a double-double.  STF 3012: m1=9.5, m2=9.8, sep 2.9" at 190 deg.

STF 3013 is 53 seconds away and m1=8.5, m2=10.2, sep 3.2" at 277 deg.

 

It's a very interesting looking formation in my 6" apo at 243x.

 

According to the WDS catalog, this is likely a physical system of four stars, with a great separation between the two pairs.

This four star system is about 249 ly away.

Wow John...   See what you have started ??

A good challenge. 

Actually, there are five (5) stars in the system, with DOB 18 part of the AB mix.

 

Thanks for starting this discussion. It has been a fun, challenging target.



#10 ssmith

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Posted 11 October 2019 - 12:36 PM

I don't believe that there are five stars involved.  DOB 18 seems to only include the AD & BD components of the STF systems

 

Here is a plot I made along with the WDS data from Stelle Doppie.

 

STF 3012&3013 Plot.jpg

 

STF 3012&3013 stelle doppie.jpg


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#11 John Fitzgerald

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Posted 11 October 2019 - 12:38 PM

I don't believe that there are five stars involved.  DOB 18 seems to only include the AD & BD components of the STF systems

 

Here is a plot I made along with the WDS data from Stelle Doppie.

 

It looks just like my pencil sketch.smile.gif


Edited by John Fitzgerald, 11 October 2019 - 12:39 PM.

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#12 dmdouglass

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Posted 11 October 2019 - 12:52 PM

I don't believe that there are five stars involved.  DOB 18 seems to only include the AD & BD components of the STF systems

 

Here is a plot I made along with the WDS data from Stelle Doppie.

 

attachicon.gif STF 3012&3013 Plot.jpg

 

attachicon.gif STF 3012&3013 stelle doppie.jpg

I agree again, and stand corrected.



#13 fred1871

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Posted 11 October 2019 - 09:16 PM

Hi David -

 

Nice photo Dave but I believe it only shows the unresolved AB & CD components.

 

This is truly an incestuous system STF 3012, STF 3013 & DOB 18 all commingled.  This may be  a perfect candidate for John Nanson to untangle the historical context. 

 

Here is a ALADIN Plot showing the GAIA data which seems to confirm the Physicality of all four stars.

 

 

Not a difficult one to untangle the historical context, if you look at the WDS dates of first measures, plus note the assigned names.

 

The components of STF 3012 and STF 3013 as listed in WDS give first date measures, which for the main components are listed as STF followed by letters, and date 1831. The 'D' component is a later addition to the list, by Doberck in 1909, now measured from A and B.

 

The opportunity for muddle comes from the CD measure of STF 3013, labelled as STF, but apparently the same D star that Doberck later listed. So, only issue is whether Struve measured star D, or whether this is a labeling error in the WDS, and should read DOB rather than STF for CD.

 

Without digging out a copy of Struve's Mensurae Micrometricae I can't be certain, but I suspect it's a labeling error, and should be DOB 18CD. That would be consistent with the other DOB 18 entries. 



#14 Nucleophile

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Posted 11 October 2019 - 10:47 PM

Interesting reading. I decided to take a look tonight. All of my "observing" is with a camera. Then i study the results.  And i think on this one, we may have a discussion here...

David:  It looks like you captured wisps of galaxy PGC 1513826 as well! 

 

It is sitting above CD just inside the box.  For reference, look at the Aladin image Steve posted.  Cartes du Ciel lists the mag at 16.5, but it does have a nice, dense nucleus meaning those with moderate aperture at a dark site may see it in the same field as the two doubles.


 

A double-double and a galaxy:   nice find, John!


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#15 ssmith

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Posted 12 October 2019 - 08:07 AM

John -

 

No controversy at all - just an interesting system.  Thanks for bringing it to our attention.  In fact it may have moved into my "most interesting" list. 

 

It is a nice compact "double-double" and truly physical which can't be said of most such touted systems.

 

I managed to get a shot of it last night.  The image is a little soft - I was shooting thru high 'frosty' cirrus clouds that covered most of the sky that were illuminated by the full Moon. The D component shows a hint of color.

 

Scope was my C9.25 & a 2.5x Powermate.

 

STF3012 & 3013 C9 2x 10-11-19 273e.jpg


Edited by ssmith, 12 October 2019 - 08:09 AM.

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#16 John Fitzgerald

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Posted 12 October 2019 - 08:53 AM

That is a great picture, IMO. Thanks much.

#17 CarlosB

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Posted 12 October 2019 - 06:44 PM

Not a difficult one to untangle the historical context, if you look at the WDS dates of first measures, plus note the assigned names.

 

The components of STF 3012 and STF 3013 as listed in WDS give first date measures, which for the main components are listed as STF followed by letters, and date 1831. The 'D' component is a later addition to the list, by Doberck in 1909, now measured from A and B.

 

The opportunity for muddle comes from the CD measure of STF 3013, labelled as STF, but apparently the same D star that Doberck later listed. So, only issue is whether Struve measured star D, or whether this is a labeling error in the WDS, and should read DOB rather than STF for CD.

 

Without digging out a copy of Struve's Mensurae Micrometricae I can't be certain, but I suspect it's a labeling error, and should be DOB 18CD. That would be consistent with the other DOB 18 entries. 

F. G. W. Struve in his catalog MENSURAE MICROMETRICAE published in 1837 describes his measurements of the two doubles. It names the components of the first pair (3012) as A and B, and those of the second pair (3013) as A 'and B', which are currently C and D. Therefore, I believe that there is no error in WDS

 

Captura2.jpg



#18 CarlosB

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Posted 12 October 2019 - 06:52 PM

Yesterday I made this shot of it. There was good seeing, without clouds and with the moonlight. I used my 8 '' Skywatcher with a ZWO ASI 120 MM camera. The north is down and the east on the right:

 

STF 3012_4.jpg

 

My measurements made with Reduc are:
AB 2.7 '' 191 °; AC 51.4 '' 67 °; AD 48.9 '' 65 °; BC 52.9 '' 65 °; BD 50.4 '' 63 °; CD 3.2 '' 278 °


Edited by CarlosB, 13 October 2019 - 03:01 AM.

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#19 fred1871

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Posted 12 October 2019 - 08:38 PM

It appears that I partly misread the WDS entries, probably a result of Doberck being listed as if there were a separate extra star. WDS treats the two pairs as a single system, therefore the puzzle is how we get the DOB 18 entry interpolated into the Struve-discovered components. When the various components are already known, it isn't usual to assign a new discoverer name because someone measures a new combination of the known components, in this case AD and BD as per WDS.

 

Obviously Doberck will have published these particular component combination measures. Why this is sufficient for a change in naming, when naming usually signifies discovery, is the puzzle. I'll inquire further.



#20 ssmith

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Posted 14 October 2019 - 09:40 AM

Fred -

The convention seems to follow that of Epsilon Lyra where each pair has it own designation and then a separate designation for the combined system.

The only curious thing seems to be why weren’t measures to the C component provided? And did Doberck have some data such as proper motions that would lead him to believe the systems were linked other than their proximity.
Struve obviously didn’t leap to that conclusion.

Edited by ssmith, 14 October 2019 - 09:46 AM.



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