Multiple Targets. Thoughts. Stupid Question?

British Astronomical Association, Variable Star Section (BAA-VSS)
Sat, 02/17/2024 - 20:58

I was wondering how others handle the very tempting multiple targets that pop up on VPhot when you set up a sequence.

Given that there seems to be very little effort for some reward, do others just accept them and report?

I get that the primary target determines the choice of comps so I try not to compromise that.

Is there a danger of sacrificing quality for the sake of quantity?


American Association of Variable Star Observers (AAVSO)
Multiple targets (not a stupid question)

"I get that the primary target determines the choice of comps so I try not to compromise that."

You don't have to compromise measurements of the primary target at all.  Make a separate sequence for each target you want to observe in that field and report data for each target separately.    If you use ensembles then the only difference in each the sequences is usually just the target.  Sometimes I will pick a different check star to get a better color match for the secondary target. 

The real problem is that the secondary target(s) often would be better off with a different exposure, so the SNR's may be poor.  Then you have to decide if you want to report measurements with embarrassingly high error estimates.  If other observers are making better observations of the secondary target I'll pass.  If there are few or no observations of the second target I'll report my measurements.


American Association of Variable Star Observers (AAVSO)
I asked this same question a…

I asked this same question a couple of years ago when I first started with variable stars.  Ken responded with this useful info:

"This is a frequent question that elicits a wide range of opinions! IMHO, the quick answer is no, go ahead and report the other variables.  However, understand that if you report one variable magnitude to the AAVSO Database and never again, that single data-point will serve little/no purpose. The better option is for you to take responsibility for gathering sufficient data for this additional target(s) so that you could provide additional astrophysical information and help confirm its properties. Are you up for that? Don't just consider GCVS variables. Have you noticed all the VSX variables in your field?"

Here is the full thread: