ATA Dishes and Beamshapes Peter K. G. Williams •
[email protected] 3GC-II • Algarve, Portugal • 2011 Sep 27
Basic Design — Offset Gregorian
Harp et al. 2011
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Seth Shostak
Basic Design — Movable Feed
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Basic Design — Movable Feed
Harp et al. 2011
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Basic Design — Hydroforming
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Primary Beam Power Pattern
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Harp et al. 2011
Primary Beam Power Pattern
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Harp et al. 2011
Primary Beam Power Pattern
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Harp et al. 2011
PBPP Consistency
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Spillover
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Squint
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“Hex” Observations ●
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Seven pointings in hexagon centered on calibrator Selfcal to get gains, solve for Gaussian PB for X and Y feeds Weekly observations Many frequencies, focus settings, epochs, feed revisions, times of day, etc See MacMahon & Wright 2009; Burns, Williams, Bower, et al in prep
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Squint
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Squint — 3GHZ Ensemble Results
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Squint — Repeated Measurements
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Squint — Frequency Dependence
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Polarimetry
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Polarimetric Response
de Villiers & Law, 2010
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de Villiers & Law, 2010
Polarimetric Response
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Polarimetry — Stokes Corrections ● ●
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Averaging over all antennas! Seven real parameters for gain and leakage errors See de Villiers & Law 2010, Sault et al 1996 for equations (messy)
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de Villiers & Law, 2010
Polarimetry — Stokes Corrections
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de Villiers & Law, 2010
Polarimetry — Stokes Corrections
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Feed Focus
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Harp et al. 2011
Feed Focus Behavior
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Harp et al. 2011
Focus Behavior — Astigmatism
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Focus Behavior — In Practice
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Focus Behavior — In Practice
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Focus Behavior — In Practice
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fin
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References ●
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de Villiers, M. & Law, C. J. 2010, ATA Memo #88. Harp, G. H., et al. 2011, ITAP 59 2004. MacMahon, D & Wright, M. 2009, ATA Memo #83. Sault, R. J. et al. 1996, A&A 117 149.
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