This section describes some common practices for selecting and observing standard stars. To recapitulate: the purpose of observing standard stars is to allow the instrumental magnitudes measured for programme objects to be converted into calibrated magnitudes in the target standard photometric system. The effects which the calibration must remove are atmospheric extinction and the mismatch between the instrumental and standard systems.
Though the procedures described here are often good practice they are
not always appropriate. Clearly you should tailor your choice of
standards and observing practices to the aims of your programme.
Indeed, there are some sorts of photometric programme for which it is
un-necessary to observe standard stars at all.
The CCD Photometric Calibration Cookbook