[Aavso-photometry] Question about identifying ref stars and SNR

[Yenal Ogmen]

Hi,
I have two questions needed to be answered:

1) I have faced with a problem in identifying
magnitudes of reference stars of the same magnitude in
CCD box. For example RR Peg chart has two 113
reference stars, and in the CCD Box there are 11.303
and 11.321. How can I know which star's magnitude is
which one?

2) I am planning to reduce exposure time and number of
stacked frames to have more time for observing more
variables. So this will pull my SNR down. Therefore,
what is the lowest value for SNR which photometry can
be done accurately?

Thank you all.

Yenal Öðmen
  Green Island Observatory Homepage
www.geocities.com/yenalogmen 
Geçitkale 
North Cyprus



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