[evlatests] pointing curiosity

[Jim Ulvestad]

I don't suppose there's any reason to believe that some
part of the on-line system now believes that the VLA Q-band
feeds are located at the new EVLA position rather than the
old VLA position?  Depending on where that might happen
in the system, I certainly have no idea what the effect
might be.

Jim

> There was a pointing run last night which was rather boring
> except for the Q band results.  All the VLA antennas, except
> for VA08, provided no solutions; all the trials were rejected
> on the grounds of estimated beam width.  When the threshold
> was increased by about 10 percent solutions were provided
> for all the VLA antennas and all antennas wanted a change
> in azimuth collimation of about +0.25 arc-min.  Collimation
> at all other bands, including K band, were reasonable.  I
> do not believe this result and have not changed any of the
> VLA Q band collimation terms.
>
> All the EVLA antennas, except EA14, were well collimated
> at Q band.  Collimations were updated for EA14 at C and
> Q band.
>
> There has been an earlier collimation run, without Modcomps,
> claiming that all the VLA antennas were fine.
>
> It seems we must have broken something between August 30
> and September 22.  It cannot be subreflector rotation, for
> a small change there would move the beam mostly in elevation.
> Can anyone thing of something we changed which affects
> azimuth pointing, but only at Q band, and onlt for VLA
> antennas?
>
>
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