Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 03/02/2023 - 00:16

Hello,

A newbie question here: where do I find information about the color of a given comp star (CCD photometry)?

VPHOT tells me which comp stars are in a given field but I couldn't find the color data about them.

Thanks,

Ari

Affiliation
American Association of Variable Star Observers (AAVSO)
VSP

The Variable Star Plotter (VSP) Photometry Table provides the mags of the comps in all selected filter bandpasses and also reports the B-V color. Take a look. By default it shows V mag and B-V.

Affiliation
American Association of Variable Star Observers (AAVSO)
In VPhot

BTW, in vphot, if you open the Measurement Details page for a specific comp, you can 'edit sequence' and see the reported mags of the comp. It is easy to calculate B-V in your head.

Affiliation
American Association of Variable Star Observers (AAVSO)
It would be nice if B-V…

It would be nice if B-V could be plotted for the comps on the chart (makes finding a comp with similar color as the variable a bit easier).

Keith

Affiliation
American Association of Variable Star Observers (AAVSO)
Crowded?

Keith:

I think that additional info might generally be too crowded and perhaps confusing? Don't you?

So, you are left with looking at the chart's photometry table.

Ken

Affiliation
American Association of Variable Star Observers (AAVSO)
No not really to my eyes,…

No not really to my eyes, but definitely not a big deal to cross-reference the table.

Keith