[evla-sw-discuss] Dwell times

Walter Brisken wbrisken at nrao.edu
Wed Jul 11 18:45:58 EDT 2007


As Barry says the below would be straight forward to offer and useful for 
observers.

As described below the same dwell time would be imposed for all sources 
with a calibrator code.  This may not be desirable for narrow bandwidth 
bandpass calibration or polarization calibration, so the scheme below will 
have to be improved a bit to be of general use.

-Q


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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