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Legacy Eclipsing Binary Stars for Visual- Is There Interest?

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SET's picture
Legacy Eclipsing Binary Stars for Visual- Is There Interest?

Dear Visual Observers,

Someone suggested to me that perhaps we should put together a list of "Legacy Eclipsing Binary Stars", like the Legacy LPVs or Legacy CVs. I'd like to know your thoughts on this. Eclipsing binary observing is my specialty. AAVSO doesn't seem to be publishing visual observations of eclipsers anymore, but they do welcome them to the International Database. My visual observations are actually being published now by the Variable Star Observers League of Japan.

I would be happy to put together a list of say 30 "Legacy Eclipsing Binary Stars". Perhaps Sebastian can add more for the farther southern hemisphere.

I need your input before I do this. If there is no interest, then I will not bother. This was a suggestion by another AAVSO member.

Chris Stephan  SET

Robert Clyde Observatory

Sebring, Florida  USA

GTN's picture
"Legacy Eclipsing Binary Stars"

These are great ideas, Chris!  Visual observing of EBs seems to have dropped off the radar, and I'm glad you've brought up the subject.  This should make for some interesting discussions!  I'm going to run a couple of ideas up the flag pole and see if anyone salutes.

In addition to the Legacy Visual EBs, a list of under-observed, bright, large-range, EBs, which have not had TOMs observed for a long time would provide visual observers another option, with a clearly defined goal.  I believe the CCD EB section has a list of program stars, simillarly constructed, and the visul EB data base might benefit from a similar, defined, program.  The list doesn't have to very long, and therre are lots of EBs!

Two new EB iniatives occur to me that would give visual observers of EBs other  options of objects to add to their choices of what to observe.  One is the ocassional monitoring of the EBs that have stopped eclipsing.  Analogous to the CV monitoring activities, this type of  project might attract new visual observers to observing EBs.  (If the dynamics are right, the EBs may start eclipsing again on relatively short time-scales.)  A second idea to raise up the flag pole is the addition of faint, high-amplitude EBs to the mix.  Large amateur telescopes are now common, and not all observers want to get into CCD work.

That aside, the Legacy Visual EBs should be given priority.


Thom Gandet (GTN)

Lizard Hollow Observatory

Tucson, AZ

HQA's picture
Legacy eclipsing binary stars

I can obviously see the interest in visual observing of binary stars in an asthetic sense - those stars with pretty color or in a nice field, watching a rapid eclipse to see the variation with your own eyes, etc.  However, as Gary Billings has said on more than one occasion, many of the old "standards" in the binary field are being actively monitored by the CCD observers.  Such CCD times-of-minima have far better accuracy than any visual observation, so from a scientific point of view, spending a lot of time getting a visual ToM for those stars with the hope that a researcher will make use of that timing is not making the optimal use of your observing hours.

Therefore, I'm hesitant to have a list of "legacy binaries" that HQ directs people to observe, without a LOT more information.  Someone needs to look at the original legacy list, and data-mine the ToM databases - the AAVSO's through the publications by Gerry Samolyk and Marv Baldwin, the Lichtenknecker database maintained by the BAV, etc. and make sure that a particular star isn't on the radar screen of the CCD observers.  Show me a star for which we have a hundred years of dense timing, one that is doing something interesting, and is not being observed by someone else.  Such a star is then a candidate for a legacy list (and might be good targets for DSLR observers, too).  Thom Gandet suggested a couple of other possible projects, such as stars where the eclipse has stopped due to apsidal motion and we might want to monitor for recurrence of the eclipse cycle, etc.  My guess is that many of these objects are being covered by the surveys, such as ASAS or SuperWASP, but there may be a few interesting objects not being observed.

The other issue is the Time of Minimum calculation itself.  As opposed to the LPV legacy list, where all you need to do is submit visual brightness estimates, ToM requires an extra analysis step. As Gerry has said before, he has no means of calculating such a ToM from visual data; that was implemented in a QuickBasic program years ago on a defunct computer.  He also does not have the time to handle visual data in addition to the excellent work that he does for the CCD timings.  We have no expertise, nor staff time, to do this at HQ.  However, there are some groups, such as at the VSOLJ or perhaps the BAAVSS, that appear to be creating ToMs from visual data.  I recommend that, if you want visual ToM, you submit your observations to the AID (the raw observations might potentially be used for other projects, so archiving them is wise) and then ask one of these other groups to download the data and do the analysis.


SET's picture

As I mentioned in one of my posts, VSOLJ is publishing my observations of eclipsers in their yearly journal. Let me just suggest, out of common courtesy, ask for their permission first. That's what I did, since I had continual contact with one of their main eclipser observers for years. He contacted their Director and he gave the approval.

Arne and HQ have done a good job of continuing a good working relationship with VSOLJ and BAAVSS.  I do exactly what Arne mentions in his last paragraph. I put my observations into the AAVSO International Database, and then copy it and forward it to Japan. It's a simple process. But do ask them for permission, first. I don't know if they did a special favor for me since I collaborate with one of their own, or if they are open to others from AAVSO participating.

Chris Stephan  SET

Sebastian Otero
Sebastian Otero's picture
Hi, Chris, Arne, Thom,

Hi, Chris, Arne, Thom, all,

Although I love eclipsing binaries too, I agree that determining ToMs visually is not something very useful in the CCD era. Is there solved eclipsing binary that hasn't been covered by the surveys?

If the stars are known to be EBs, the answer is probably no, although there are exceptions.

The exceptions are those stars that have one or just a few eclipses detected, not enough to determine their orbital periods. Then, the goal is to detect an eclipse, not to get a time of minimum. I think this is more valuable and is worht spending time. I have solved ten or so bright eclipsing systems this way. Chris and I were able to solve V353 Hya this way, back when only a few ASAS-3 and Hipparcos observations were available. Now the number of unsolved stars is smaller but there are still plenty of them. Of course, most of them have small amplitudes and are challenging for visual observers but a few are very suitable and catching an eclipse could allow a period determination.

I have a list of them here:

I haven't updated it for some months but most should still be unsolved. One of the brightest and most interesting is KP Vir. It can be even observed with binoculars.
Its range is 8.35 - 8.70 in V.
Other two that are worth observing are: V916 Her (V= 7.97 - 8.47:), V539 Lyr (V= 7.27 - 7.61:).
Going fainter, to telescopic stars we have:
V1125 Tau (V= 8.66 -9.25:); V795 Cas (V= 8.86 - 9.11:); V2077 Cyg (V= 9.07 - 9.51:); PW Gem (V= 9.10 - 9.47); HD 139388 (V= 9.14 - 9.5:); SAO 25077 (V= 9.77 - 10.10); SAO 3858 (V= 10.00 - 10.40); GSC 04419-01914 (V= 10.85 - 11.3) and several more fainter than 11th mag. that you'd better check on the list.

Most of these stars will turn out to be long period eclipsers (periods >5 days for most of them and probably >10 d. for the remaining ones) or eccentric binaries, a fact that makes finding periods more difficult when there are not many eclipses recorded.

So this is a hunting task. Observe every clear night looking for a dip. Some tips on how to observe are given on my page. Basically, you need to get used to how the star looks when it is at maximum. Patience will be required. You may spend a lot of time without detecting anything unusual. That makes it even more exciting. I can say from my own experience that when you detect an eclipse after months or years without any activity, you realize that it was worth the wait ;)


PS: Chris, I can't give a list of Southern eclipsers to monitor because I mostly observe those with no period.


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