[daip] forwarded message from Eric Greisen

[Eric Greisen]

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From: Eric Greisen <egreisen at nrao.edu>
To: Hanno Spreeuw <hspreeuw at science.uva.nl>
Subject: Re: [daip] question about SAD
Date: Fri, 15 Dec 2006 13:45:49 -0700

Hanno Spreeuw writes:
 > Hello, I have a question about SAD, does it take into account background 
 > levels? In other words, do the reported fluxes have the background 
 > subtracted?

   I do not see anything about fitting a DC level or rather a sloping
background as in IMFIT/JMFIT.  The islands used in SAD are small
enough that a bckground fit would be too many free parameters.

 > Is there any was to take account of a varying rms in the map?
 > 
There is a task RMSD which will attempt to make an image of the RMS
over your field of view.  SAD can read that image and use it in error
estimates and the like.

Eric Greisen
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