Proposal #670

Comments

(3663) Dirk Terrell — Jan. 9, 2026, 4:44 p.m.

Your proposal leaves a lot to be said. What is your motivation for observing this object? When you say "1 cycle", what does that mean exactly? One cycle continuously or enough observations over multiple cycles that can be phased together to produce a full light curve?

(53101) Roger Berry — Jan. 10, 2026, 5:44 p.m.

Hopefully this proposal will be more descriptive, thanks for your response.
The physics professor of the local college has asked me to collect data on EB class A binaries that his students can deduct that can be used to help determine properties from the light curve.
The EB in interest is FG Gem that has a transit period of, according to VSX, of 2.75 h.
My request is for a capture period that starts 30min before the transit to 30 min after the transit.
I would request 30sec captures during the event.
Filter used will be a V filter
My first request, so I'm learning more on how to submit a proposal more appropriately.

(2108) Arne Henden — Jan. 10, 2026, 6:56 p.m.

Hi Roger,
When discussing eclipsing binary stars, researchers use the terms "primary eclipse" and "secondary eclipse" to refer to the deepest and shallowest eclipse respectively as the stars pass in front of one another. The term "transit" is reserved for cases where a small, dark, body passes across the disk of a much larger star - usually an exoplanet (or transits of Mercury or Venus in our Solar System). Your use of transit confused us. In addition, the 2.75hrs refers to just the primary eclipse and does not describe the total light curve, which is 19.7hrs long and includes the secondary eclipse. Both eclipses are usually required if you are to determine properties such as the star temperatures or sizes. That is why "one cycle" means 19.7hrs and not 2.75hrs, so another point of confusion.

So the question is what exactly you want to obtain? If it is just a single primary eclipse, then ~3.75hrs of data is sufficient, but you have to use the "ephemeris" feature of VSX, along with the longitude of whatever telescope system is assigned, to provide that ~4hr window during night-time so that we can generate a scheduled observation plan. If it is an entire 19.7hr light curve of the total system, then we can't do it in a single night and need to obtain segments that can be stitched together.

(53101) Roger Berry — Jan. 10, 2026, 9:02 p.m.

Thanks for getting back to me again.

Thanks for the clarification on "eclipse" vs "transit". That will help me out in the future.

We are looking for the entire eclipse to include the "primary" and the "secondary" eclipse. Looking at an ephemeris, the secondary eclipse is approximately 10h10m after the primary. Requesting number of nights necessary to complete and after we get the data will stitch together for complete light curve.

I plan on using VPhot to create the light curve.

My next question is, does the AAVSO assign the telescope or do I select?

Thanks again

(2108) Arne Henden — Jan. 10, 2026, 9:18 p.m.

The AAVSO will assign a telescope, most likely BSM_NH2 or BSM_NM based on the declination of the target and its brightness. This is winter, so if approved, it may take a while to get the entire light curve (or at least the primary/secondary eclipse part of it) as weather is iffy. I also recommend at least B and V exposures, as having color information really helps in modeling the system.

(3663) Dirk Terrell — Jan. 12, 2026, 5:02 p.m.

And when it comes time to do your analysis, I will be happy to assist.

(53101) Roger Berry — Jan. 12, 2026, 5:58 p.m.

Will definitely do that.
Thanks

(4726) Kenneth Menzies — Jan. 16, 2026, 9:51 p.m.

So Roger, are you able to find the times of primary and secondary eclipse for some future period of time assuming that the BSM_NH scope will be used for imaging?

(53101) Roger Berry — Jan. 17, 2026, 6:47 p.m.

If BSM_NH is the telescope in New Hampshire then a possible imaging date would be on the 19th and 20th.

All times in EST:

1-19-2026

(53101) Roger Berry — Jan. 17, 2026, 6:56 p.m.

Sorry about that:

1-19-2026 21:37 secondary eclipse
1-21-2026 Time of minimum for primary eclipse 03:07
These times were acquired from the Mt.Suhora Astronomical Observatory Timing Database.

According to AAVSO ephemeris the timing for the primary are:
All times EST:
Start: 00:32 hrs
Mid: 02:24 hrs
End: 04:16 hrs

Comments on this proposal are closed.