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Lessons learned from station calibration

Lessons learned from station calibration. Parisa Noorishad, Arnold van Ardenne and Thijs van der Hulst AAVP2011, 12 th - 16 th Dec. 2011 Dwingeloo- The Netherlands. Parisa Noorishad AAVP2011, 12 th - 16 th Dec. 2011 Dwingeloo- The Netherlands. AA-station calibration (gain calibration).

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Lessons learned from station calibration

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  1. Lessons learned from station calibration Parisa Noorishad, Arnold van Ardenne and Thijs van der HulstAAVP2011, 12th- 16th Dec. 2011Dwingeloo- The Netherlands Parisa NoorishadAAVP2011, 12th- 16th Dec. 2011Dwingeloo- The Netherlands

  2. AA-station calibration (gain calibration) • Aim: receivers' DI-complex gain • Methods used by far: • Model-based methods (covariance fitting) • Holographic method • Redundancy (in case of a regular array) • Deterministic effects not to dismiss: • Non-identical beam of the station elements • Beamformed beam of the station elements (complex weights of digital beam) • Beam projection/sky rotation • ...

  3. Some Demonstrations

  4. 1.1 Non-identical beams

  5. 1.2 Non-identical beams 24th Nov 2009 21:29:04 UTC, observing CasA

  6. 2.1 Complex weights of digital beam Digital Beamforming weights f= 160MHz

  7. 2.2 Phase of DI-complex gain Tracking CasA, 24th Nov 2009 @ 22: 12: 19 UTC

  8. 2.3 Phase of DI-complex gain Tracking CygA, 28th Nov. 2009 @ 19: 55: 54 UTC

  9. Suggestions for AA- gain calibration • Not to accept any direction dependency or rapid variations over time or frequency in our gain calibration results. • To know the deterministic effects (e.g. beam shape) well and separate them from the stochastic ones (e.g. correlated noise, ionosphere, etc.). • To know the beam by EM-studies. • To set identical beams as a figure of merit. • To correct for them (especially beam effect) • This hopefully leads to less variance on our parameters of interest in AA-calibration.

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