[daip] setjy

[Eric Greisen]

Rob Ivison wrote:
> dear daip!
> 
> i'm sure i've missed the announcement in a midnight job report, but we 
> noticed today that SETJY is reporting ~0.8Jy for 3C48 at ~34GHz under 
> 31DEC10 and ~0.6Jy under 31DEC09.
> 
> 31DEC09 contains the line
> 
> graems> SETJY1: / Using (1999.2) VLA or Reynolds (1934-638) 
> coefficients
> 
> whilst 31DEC10 says
> 
> horn  > SETJY1: / Using (2010) VLA or Reynolds (1934-638) coefficients
> 
> presumably this relates to the WMAP calibration efforts? is there an 
> announcement somewhere i can be directed to?
> 
> i don't understand why 31DEC09 with MNJ is reporting a different value 
> to 31DEC10 with MNJ?
> 
> ...leaving aside the horrific magnitude of the difference :-/

Rick Perley has been working on a vast collection of flux calibration 
observations (the upgrade to SETJY was initially a target for Nov 
2004!).  The 31DEC10 SETJY has been updated with the results that he 
produced.  We are still hoping for a time-dependent set of numbers 
particularly for the higher frequencies but, you will understand, the 
commissioning of the EVLA takes precedence.  31DEC09 is a FROZEN version 
of AIPS.  It is changed a few times in the course of 2010 to make modest 
corrections for egregious errors.  A significant change - such as that 
to SETJY - is not made in old versions.  This has nothing to do with 
WMAP by the way, but is dependent only on the painstaking work by Rick 
Perley with help from Brian Butler.  The 31DEC10 version has the option 
to use older flux scales (APARM(2) in 31DEC10 has been shifted upward 
from 31DEC09 to allow APARM(2)=1 to select the flux scale you get by 
default in 31DEC09).

Nothe that a MNJ on 31DEC09 produces error messages except for when a 
"patch" is announced.  See our home page (aips.nrao.edu) for a list of 
patches.

Eric Greisen
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