[daip] AIPS flux scale at 325 MHz

[Eric Greisen]

On 07/25/2016 02:54 AM, calistro wrote:
> Dear Eric,
>
> I am using a catalog of P-band VLA data which has been calibrated with
> AIPS version 31DEC12.
> The authors used the task calrd to load the L band model for 3C286 and
> from this the flux at 325MHz was calculated by AIPS.
> Since I am working on spectral curvature study I need to have the fluxes
> at all bands consistent to one scale, in this case the Scaife&Heald12.
> Unfortunately, the scaling of the P-band VLA data mentioned above is not
> clear to me, because of the different versions and I was wondering if
> there is some information available which I have missed, where I can
> find out the conversion factor from the AIPS scale at that version to
> the Scaife&Heald12 scale.
>
> Thank you in advance for you answer and all the best,
> Gabriela Calistro Rivera
> ---
> PhD candidate at Leiden Observatory
>
>

Unfortunately, the Scaife & Heald fluxes were put into AIPS in April 
2013, thus in the 31DEC13 version of AIPS.

In October 2012 I added Perley/Butler 2013 values for 3C286 and 3C295
but due to an error the 2010 values continued to be used until June 2013.

SETJY allows the users to specify which of the historical values they 
wish to use so it is not entirely certain what the authors of the 
catalog may have used.

C                                       Perley 2010 coefficients
C                                       same units as RCOEFF
C                                       3C286
       DATA TCOEFF /1.2361,  -0.4127,  -0.1864,   0.0294,

          TEMP2 = TCOEFF(1,ISRC) + DT * (TCOEFF(2,ISRC) + DT *
      *      (TCOEFF(3,ISRC) + DT * TCOEFF(4,ISRC)))

where DT is the log base 10 of the frequency in GHz
and the flux is then 10**TEMP2

	I hope this helps

Eric Greisen