Extended Q-band (eQ) receiver for Nobeyama 45-m Telescope

The Ka-/Q-band in the microwave region of the electromagnetic spectrum is important for astrophysical and astrochemical research, particularly in the subfield of interstellar medium (ISM). The two bands cover not only the fundamental lines of the abundant dense gas tracer CS and its isotopologues but also a vast number of transitions of relatively large, long-chain, and/or complex organic species. Here, through a Taiwan-Japan collaboration, an extended Q-band (30-50GHz) receiver is built for Nobeyama 45-m telescope. The receiver front-end was installed at Nobeyama 45-m telescope in Nov. 2021 and obtained its first light in the same month. Commissioning and science verification (CSV) of the receiver was conducted in the first half of 2022. After commissioning, this receiver will be the only one in the world providing capability to cover 3 Zeeman transitions simultaneously at 7mm wavelength installed at large single dish telescope. It will be one of the most powerful facilities to explore the magnetic fields towards the pre-protostellar cores.