Taeduk Radio Astronomy Observatory (TRAO) was established in October 1986 with the 13.7 meter Radio Telescope and a single-horn receiver system operating for the frequency range of 86 to 115 GHz (3 mm wavelength range). TRAO opened the new era of the millimeter-wave radio astronomy in Korea as one of the main facilities of KASI. Research activities have been focused mainly on the molecular cloud, star formation activity and evolution, supernova remnants, line survey and observations of maser lines around the late type stars. Since 2009, large area observations have been carried out using the 15-pixel multi-beam receiver system (old QUARRY).
Recently, we re-open our system with substantial renovation of the telescope, including main computer (VxWorks), servo system, new receiver system and so on. The new receiver system, SEQUOIA-TRAO, is equipped with high-performing 16 pixel MMIC preamplifiers in a 4x4 array, operating within 85 - 115 GHz frequency range. The system temperature is ranging from 170 K (86~110 GHz) to 400 K (115 GHz; 12CO), much more improved than the previous receiver system. The 2nd IF modules with the narrow band and the 8 channels with 4 FFT spectrometers allow to observe 2 frequencies simultaneously within the 85~100 or 100~115 GHz bands for all 16 pixels of the receiver.
We provide OTF (On-The-Fly) as a main observing mode, and position switching mode is available as well. The backend system (FFT spectrometer) provide the 4096x2 channels with fine velocity resolution of less than 0.1 km/sec (15 kHz) per channel, and their full spectra bandwidth is 60 MHz. The telescope is in the 20.7 m-diameter radome, which protects the telescope from atmospheric changes, though some of radio wave could be blocked insignificantly. In Feb. 2017, the radome replacement of TRAO was also completed successfully.
Operation for the internal users started in early 2016, and the full operation was started from the fall season 2016 to all international users.