[evlatests] Antenna slews in AH1004

[Ken Sowinski]

On Mon, 8 Mar 2010, David Harland wrote:

> In the 3rd paragraph i said that i don't think what we're doing w/ the
> setWrap generation should result in any different behavior for this example.
>
> One of AH1004's SBs has 29 scans.  Here's what we're changing:
>
>    Old code: all 29 scans have "subarray.setWrap(0)"
>
>    New code: 1st scan has "subarray.setWrap(0)", none of the other
> scans trigger a call to setWrap.
>
> Based on Ken's statement, old code and new code should give same
> behavior for this particular SB.  So, i'm asking if the conclusion that
> "this is excited by the OPT-generated script" and its handling of wraps
> can really be the reason that things went fluey on several antennas.

I am a little confused by this discussion.  Ny understanding:

1.  For the case in question, AH1004, David is correct, the outcome
will be the same regardless of the script generation algorithm.

2.  To fix AH1004 requires a setWrap(-1) for the first scan which
observes in the NE quadrant and requires a following setWrap(0)
before the source has moved through the South to the NW quadrant.
The setWrap(0) ought to be set for the following scan, but if that
occurs before the antennas have unambiguously moved to the inner
wrap they will use the opportunity to go the closer, wrong, outer
wrap.  The sure approach is to do the setWrap(0) for a scan which
begins at least five minutes after the scan which did setWrap(-1).

3.  What should be done in general is observation dependent.  In
the past we left it to the observer to sort out in (j)observe,
and we continue to allow that in the OPT.  Educate the astronomer.

4.  The liberal sprinkling of setWrap(0) throughout the script
is not a good thing only in the case where the observer has offered
wrap hints.  In the case where he has not they are merely irrelevant.

Ken