Arecibo Observatory

Rotating ALFA for ALFALFA

The observing mode we use for ALFALFA is very simple: we fix the Gregorian dome at proper azimuth and zenith angle corresponding to the declination we want to observe, start the data acquisition program, and let the sky drift by.

The ALFA can be rotated around its center so that the arrangement of the beams can be oriented in different patterns on the sky.

Remember that we designate the central beam as Beam 0.
For ALFALFA, we rotate the array by 19 degrees so that the resultant beam layout produces drift scans tracks that are equally spaced in declination on the sky. Beam 0 remains at the center.

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Back to ALFA for ALFALFA

Last modified: Sun Oct 7 09:55:33 EST 2007 by martha