2007PASJ...59.1005N

begin{HTML}We have upgraded the 60-cm radio survey telescope located in Nobeyama, Japan. We developed a new waveguide-type sideband-separating SIS mixer for the telescope, which enables the simultaneous detection of distinct molecular emission lines in both the upper and lower sidebands. Over the RF frequency range of 205-240 GHz, the single-sideband receiver noise temperatures of the new mixer are 40-100 K for the 4.0-8.0 GHz IF frequency band. The image rejection ratios are greater than 10 dB over the same range. For dual IF signals obtained by the receiver, we have developed two sets of acousto-optical spectrometers and a telescope control system. Using the new telescope system, we successfully detected the ¹²CO (J = 2 - 1) and ¹³CO (J = 2 - 1) emission lines simultaneously toward Orion KL in 2005 March. Using the waveguide-type sideband-separating SIS mixer for the 200 GHz band, we initiated the first simultaneous ¹²CO (J = 2 - 1) and ¹³CO (J = 2 - 1) survey of the galactic plane as well as large-scale mapping observations of nearby molecular clouds.