Re: [TASS] Martin's variable, FITS keywords, FAQ, etc.

["Arne A. Henden" <aah@NOFS.NAVY.MIL>]

Chris wrote:
>Arne says "start of exposure" is a convention, so that's what I'll
>use in the FITS image files.  I think the database should contain
>the heliocentric time of the mid-exposure so a conversion will be
>required at some point in the pipeline.
  Usually the heliocentric correction occurs after the astrometry
step has been performed.  This is fairly early on with Star, but
might be a couple of steps later with other reduction packages.
Note also that there are several time-based corrections if you
want the most accurate timing, along with proper setting of the
PC clock as mentioned by Chris.  Since these are all 'corrections',
I don't think they should be in the raw fits header, but perhaps
should be applied before adding observations to the database.
Arne