[daip] Recent changes in DBCON seen in TST in Green Bank

[Eric Greisen]

On 04/15/2015 01:50 PM, Bob Garwood wrote:
> Hi Eric,
>
> We've seen some changes in DBCON as used by the GBT pipeline in the TST
> version.  These may indicate long standing mis-uses of pseudo-uvdata to
> hold GBT data prior to gridding with SDGRD but at any rate, TST is
> currently unusable by the GBT pipeline so we need to sort out what the
> fix is before TST becomes NEW next year.
>
> We get calibrated GBT data into AIPS by converting SDFITS files to
> random group/pseudo-uvdata using a program that Glen Langston wrote
> called idlToSdfits (that we have the code for, but haven't done much
> work inside it since Glen left NRAO).  For multi-beam data, we calibrate
> the beams separately, producing a separate SDFITS file, and then a
> separate uvfits file which we read into aips and then use DBCON in aips
> to produce one data set to be used by SDGRD.  The DBCON step now fails
> in the TST version of AIPS, producing either this message:
>
> DBCON1: UVPGET: RANDOM PARMS NOT ALL THERE:  0  1  0 -1  2 -1 -1 -1 -1 -
>          1 -1 -1
>
>
> or this ...
>
> DBCON1: I CAN ONLY HANDLE STANDARD FORMS OF STOKES AXES
>
>
> We believe both of these errors have to do with the STOKES axis,
> depending on what idlToSdfits has done.
>
> In the first case, the input SDFITS files are all single polarization
> and so the STOKES axis (which is the 3rd axis in the uvfits file) is just
>     NAXIS3 =  1
>     CRVAL3 = -1
>     CRPIX3 =  1
>     CDELT3 = -1
>
> And DBCON is being asked to combine 2 of those.
>
> In the second case, idlToSdfits has combined 2 polarizations so the
> STOKES axis has 2 elements on it and looks like this:
>     NAXIS3 = 2
>     CRVAL3 = -1
>     CRPIX3 = 1
>     CDELT3 = -1
>
> Using "imh" in AIPS, the "uv" data files all reflect those values from
> the original fits files.
>
> Any advice on how we should proceed (e.g. modifying the output of
> idlToSdfits) would be appreciated.  Thanks.
>
> Bob


A MNJ tomorrow will fix the DBCON issues.

Eric