[evlatests] pointing curiosity

[R. Craig Walker]

How about a fairly large focus error.  That would widen the beam and might
give a small pointing shift.  On the VLBA, focus doesn't affect pointing
much so, if the VLA is the same, it would need to be pretty bad.  I forget
where the 7mm feed is on the circle, but if it is near the elevation axis
where it wants to be to allow for corrections using rotation, then the
focus pointing effect is probably in azimuth.

Cheers,

Craig


> On Sat, 22 Sep 2007, Jim Ulvestad wrote:
>
>> 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.
>
> An interesting thought, but not very likely.  Rotation
> parameters have not changed for a long time.  Any small
> change of rotation would move the beam in elevation; any
> large change would make a complete mess.
>
> That said, software may have changed.
>
> Ken
>
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