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Can I make a polarization observation in Cycle 2? - Knowledgebase / General - ALMA Science

Can I make a polarization observation in Cycle 2?

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The ALMA correlators will process either linear parallel-hand polarizations (XX, YY) or single polarization (XX). Full intrinsic polarization (XY, YX) will be available in Cycle 2 for continuum observations in bands 3, 6, and 7 with some restrictions. Sources must be centered and have a user-specified largest angular structure that is less than one-third of the 12-m Array primary beam at the observing frequency in use. Observations must be single-field, but multiple sources within a 10 degree area on the sky are possible with one field per source.

Continuum polarization measurements are offered only for specific frequency settings listed below:

Band

SPW1

(GHz)

SPW2

(GHz)

LO1

(GHz)

SPW3

(GHz)

SPW4

(GHz)

3 90.5 92.5 97.5 102.5 104.5
6 224.0 226.0 233.0 240.0 242.0
7 336.5 338.5 343.5 348.5 350.5

Note for the table: Fixed central frequencies for four TDM spectral windows, each of width 1.875 GHz, and the corresponding LO1 setting. Frequencies were chosen to optimize spectral performance, and they are centered in known low noise and low instrumental polarization tunings of receivers.

Full polarization observations require sufficient parallactic angle coverage for calibrations (about 3 hours). Science Goals with properties that lead to a total observing time estimate that is less than 3 hours will have the time estimate set to 3 hours to ensure sufficient parallactic angle coverage is obtained.


See section A.6.2 "Polarization" of the ALMA Cycle 2 Capabilities for more information.