Description
We report the development of a wideband receiver system using a corrugated horn covering 210–375 GHz (56% fractional bandwidth; Yamasaki et al. 2021, PASJ), wideband waveguide multiplexers (Masui et al. 2021, PASJ), and a wideband SIS-mixer with an IF (intermediate frequency) output of 4-21 GHz (Kojima et al. 2020, A&A). In the system, the RF signal from the horn is divided into two frequency bands by a wideband diplexer with a fractional bandwidth of 56%, and then each frequency band is further divided into two bands by each diplexer. One of the SIS-mixers connected has a wideband 4–21 GHz intermediate frequency (IF) output. This receiver system has been installed on the 1.85 m telescope of Osaka Prefecture University located at the Nobeyama Radio Observatory. We succeeded in simultaneous observations of six CO isotopologue lines with the transitions of J = 2–1 and J = 3–2 toward the Orion KL as well as on-the-fly mappings toward the Orion KL and W 51 with the developed system.
