[evla-sw-discuss] Dwell times

[Michael Rupen]

This could be quite useful for dynamic files where one is trying to observe
a flux/bandpass/polarization calibrator.  Currently one must put enough
time on the calibrator scan to ensure sufficiently long observations at the
worst case LST, which can be quite a burden in a half-hour file.

I doubt this is a terribly high priority though, given how busy the folks who 
might implement it are.

               Michael


  On Wed, 11 Jul 2007, Barry Clark wrote:

> We could fairly easily offer calibrator dwell times as an enhancement
> to astronomers, through obs2script.
>
> We could have a comment card command, of the ilk
> /* CDWELL <number of seconds>
>
> Then on simple calibrator observations (that is, not reference pointing,
> not fast switching), obs2script could issue a dwell time instead of
> an absolute stop time.
>
> That is, obs2script usually says
>    <set up for calibrator>
>    subarray.execute(<stop time of previous source>)
>    <set up for next source>
>    subarray.execute(<stop time for calibrator)
>
> It could instead say, after a /* CDWELL nn card,
>    <set up for calibrator>
>    subarray.execute(<stop time of previous source>)
>    array.waitOnSource(<stop time of calibrator>)
>    <set up for next source>
>    subarray.execute(min(array.tai(array.time()+nn/86400., <stop time of calib>))
>
> array.waitOnSource() is, effectively, the routine formerly known as
> waitModcomp().
>
> I'm not in favor of offering entire files in dwell times - the operators
> will get confused if they don't know when the file will end.
>
> A fairly easy thing to offer, but a bit of a distraction.  Is it worth
> doing?
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