› Forums › Variable Stars › Calculation of SNR › Rejecting stars in the sky annulus
18 October 2020 at 9:15 pm
#583256
Nick James
Participant
The one they use in VPHOT, described on page 4 here. Essentially you calculate the mean and SD then reject pixels more than 3 sigma from the mean and repeat until no more pixels are rejected. In the past I’ve used the median to get the sky level then used pixels below the sky level to determine the SD.