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Short Description

HERA is a heterodyne receiver array for the IRAM 30m telescope. It consists of two arrays of 3x3 pixels with 24" spacing. The two arrays have orthogonal polarization (V, H) the two polarizations pointing at identical locations on the sky. The instantaneous bandwidth of each pixel is 1 GHz. HERA is equipped with a derotator allowing to follow a source in the sky maintaining the same "footprint". The tunable range is between 215 and 272 GHz. In this range the beamwidth varies between 12" and 9". The beam efficiency is between 0.57 and 0.42.

• [http://www.iram.es/IRAMES/otherDocuments/manuals/HERA_manual_v20.pdf HERA manual, version 2.0] by Schuster et al. 4.4.2006 (pdf file)

• Technical paper [http://www.iram.es/IRAMES/otherDocuments/manuals/0179hera.pdf "A 230 GHz Heterodyne Receiver Array for the IRAM 30m telescope"] (pdf file)

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Status

• 6.4.06: Note that the second polarization is difficult to tune for frequencies >241 GHz. Contact rx engineers in advance RM

• 8.1.2005: One of the 18 pixels is still blind. Only few frequencies can be tuned automatically. Observers should send observing frequencies to the IRAM Granada receiver group at least three weeks in advance.

• 1.6.2005: Tests have shown that the pixels of HERA-2 (second polarisation) have relatively strong variations of noise over the IF band (LSB Tuning). While the consequences are not too dramatic for wide band operation (WILMA) unfortunately the narrow band mode as used mostly with VESPA picks up the end of the IF band with the highest noise. The problem will be further investigated and eventual improvements indicated asap.

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The local contact for HERA is Albrecht Sievers: http://www.iram.es/IRAMES/personal/sievers/sievers.gif