[Aavso-photometry] Measuring aperture

[Barbara G. Harris]

I have been doing CCD photometry for a few years but I have been getting
back to basics and digging into how my program (mostly Maxim, but also use
AIP4Win) calculates magnitudes.  I have a question that is probably pretty
basic but I would like to have it confirmed:  When measuring the comp,
check, and variable do you have to use the same size aperture and annulus
for each star in the field or can you adjust the diameters because of field
crowding?  I have made sure to always use the same size and I assume that is
why it is recommended to use stars of similar magnitudes.

 

Barbara