HeraforAstronomers

HERA 1mm array receiver

Comments: Gim is the image band rejection. (1) Note that the HERA2 frequency range is more restricted than for HERA1. In addition, HERA2 pixels 4 and 9 are instable and should be flagged in data processing. <CK 9-May-2014>

HERA is a heterodyne receiver array consisting 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. HERA is equipped with a derotator allowing to follow a source in the sky maintaining the same "footprint". Over the range of tunable frequencies, the beamwidth varies between 12" and 9".

• HERA manual, version 2.0 by Sievers et al. 2006

• Schuster et al. 2004, A&A, 423, 1171 A 230 GHz Heterodyne Receiver Array for the IRAM 30m telescope (local copy)

• It is not possible to simultaneously observe with HERA and any of the other frontends.
• The alignment of the two polarisations is described in the HERA manual.

• Nasmyth offsets are described in the report on the commissioning of New Optics installed in April 2015.

• HERA has two local oscillators, one for each polarization. Simultaneous observations of e.g. the 12CO and 13CO 2-1 lines are hence possible with both polarisations. Note that, in addition, the C18O 2-1 line lies within the 1GHz bandpass next to the 13CO line.