Parameters

Typical parameters:

sigclip=4.5
sigfrac=0.5
objlim=2
niter=4

If the gain is unknown, set gain=0 and give an image section for computing statistics (default statsec="*,*").

For marginally sampled (or undersampled) data (i.e. sigma<1.5 pixels) use higher values of objlim. For HST WFPC2 data the following parameters give good results:

gain=7.
readn=5.
sigclip=4.5
sigfrac=0.3
objlim=4
niter=4

Use objlim=5 for a more conservative discrimination between bright stars and cosmic rays.