Hello! Before each night's run, I typically image a Landolt standard field at high and low altitudes in the unlikely event that such would be needed for future reference and for my own education.
I was wondering, with ensemble photometry, for Landolt fields in particular (or imaging runs in general) is it OK to start imaging as soon as it is dark enough to obtain an image of the field or should I wait till astronomical twilight for all images? Would photometric and standard magnitude and color values be skewed when computed with images taken before astronomical twilight? Thank you and best regards.