[daip] smodel in scimg

[Eric Greisen]

Hanno Spreeuw writes:
 > Hello, I would like to use a point source model in SCIMG with the SMODEL
 > adverb.
 > The SCIMG helpfile says:
 > SMODEL(2) = X offset in sky (arcsec)
 > SMODEL(3) = Y offset in sky (arcsec)
 > Does this mean that these are defined in the same way as the SHIFT adverb?
 > So SMODEL(2)=cos(Dec_0)*(RA-RA_0)
 > and SMODEL(3)=Dec-Dec_0?
 > Is this correct?

All shifts in AIPS are the same - so yes this is arc sec on the sky
(local to the center of the image) so your formula above.

I am unsure how SMODEL works in SCIMG - I would hope that would be a
starting image replaced after one cycle by the computer image.

Eric Greisen