Commissioning of the 30-50 GHz Receiver at Nobeyama 45-m Radio Telescope- 2 years after installation

A new extended Q-band (eQ) receiver covering 30-50 GHz for Nobeyama 45-m Radio Telescope (NRO) has been installed in November 2021, followed by the commissioning observation. With excellent receiver noise temperature of ~ 15K, the system noise temperatures at NRO are 30K at 33 GHz and 70K at 45 GHz under good weather condition. The half-power-beam-width (HPBW) of the receiver is measured to be ~ 38" at 43 GHz. The aperture and main beam efficiencies are 0.61/0.75, respectively. With 2SB scheme, each sideband with 4 GHz bandwidth, the receiver can cover multiple transitions simultaneously with very high (a few kHz) spectral resolution. With this feature and the large collecting area of NRO 45-m telescope, the eQ receiver allows us to explore astrochemistry and polarimetry toward interstellar medium in high sensitivity. In the talk, the current status and the preliminary science results from the past 2 years will be reported.