[mmaimcal]shadowing and beam elongation

Mark Holdaway mholdawa at nrao.edu
Tue Jan 29 14:42:20 EST 2002


I've made some plots that may be instructive to study:

For Boone, Conway (ie, Kogan), and Webster style compact
configurations, I've calculated the sensitivity left after
shadowing (ie, 1.0 = all sensitivity, 0.192 = LOTS of shadowing)
as a function of Hour Angle and Declination.  The shadowing is
instantaneous, ie, for a snapshot at that HA.  (I accidentally
missed HA=-1.5, which explains the ugly line I've got there.)
Sub-elevation points are blank.


Also, I've calculated the beam elongation for these arrays,
except that the beam elongation is cumulative, ie, the HA=2
point is the beam elongation (Bmaj/Bmin) for a -2 to +2 hour
track.  If lots of shadowing occurs, for example, beyond 2 hours,
the elongation will not change very much at 3 and 4 hours.

Mosaic image quality is in the pipeline.

While the CDR is pushing us towards the Kogan array, seeing the
strengths and weeknesses of all three arrays in comparison should
be helpfull in improving and finalizing the Kogan design.

	-Mark

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