[daip] Request to include GMRT primary beam parameters in Aips {External}

[Eric Greisen]

> Hi Eric,
>
> I am going to try Imagr on wideband uGMRT data (300-500 MHz) using the
> wideband option that worked quite well on simulated data.
> To fit for spectral indices of sources far away from the primary beam
> centre, one need to apply primary beam correction on the fly during
> imaging via Imagrprm(1).
> However, in absence of primary beam parameter for GMRT in Aips, it will
> assume an Ideal antenna (of 45 meter diameter), which is not quite right.
>
> Therefore, I am attaching a summary document from our webpage
> (http://www.gmrt.ncra.tifr.res.in/doc/beam-shape-v1-09sep2022.pdf), which
> provides the uGMRT beamshapes for different frequency bands.
>
> Request to incorporate them in Primeary beam related Aips source files.
> I typically use a primary beam cut-off level >0.05.
>
> Thanks,
> Subhashis
>

I am assuming that the array name in the ANtenna file and the telescope
name in the headers is GMRT.  This is needed to trigger proper handling
of things.  I had assumed that IMAGR simply used to adverb value for
some approximate beam and have discovered happily that it is much smarter.

Working on it...

Eric