We present a multi-dimensional reduction method of the surveyed cube database obtained using a single- dish radio telescope in Taeduk Radio Astronomy Observatory (TRAO). The multibeam receiver system installed at the 14 m telescope in TRAO was not optimized at the initial stage, though it became more stabilized in the following season. We conducted a Galactic Plane survey using the multibeam receiver system. We show that the noise level of the first part of the survey was higher than expected, and a special reduction process seemed to be definitely required. Along with a brief review of classical methods, a multi-dimensional method of reduction is introduced; It is found that the ‘background’ task within IRAF (Image Reduction and Analysis Facility) can be applied to all three directions of the cube database. Various statistics of reduction results is tested using several IRAF tasks. The rms value of raw survey data is 0.241 K, and after primitive baseline subtraction and elimination of bad channel sections, the rms value turned out to be 0.210 K. After the one-dimensional reduction using ‘background’ task, the rms value is estimated to be 0.176 K. The average rms of the final reduced image is 0.137 K. Thus, the image quality is found to be improved about 43% using the new reduction method.
We present results of a test-study of the large-scale survey using the multi-beam receiver system recently installed on the 14 m telescope at Taeduk Radio Astronomy Observatory (TRAO). We have tested several modes of mapping, and found suitable (time-saving) mapping parameters of 'ON-SOURCE' = 8, 'OFF-SOURCE' = 1 when using 'RPT' = 3 as a position-switching mode. We observed 504 spectra towards the NGC 7538, a star forming molecular cloud in the transition of J = 1 - 0 of 12CO . From the Outer Galaxy Survey database (Heyer et al., 1998) we obtained 504 spectra for the same region. We compared integrated intensities, line profiles of two databases, and found that they are consistent to each other. From the intensity ratio of these two databases we also found that the value of forward spillover scattering of the TRAO telescope system is 0.58.
We have mapped 17 deg2 region toward Galactic anticenter in 12CO J = 1 - 0 using the 3 mm SIS receiver on the 14 m telescope at Taeduk Radio Astronomy Observatory (TRAO). The region mapped in this paper is the first target of the Galactic AntiCenter CO Survey Project (GACCOS) and was selected comparing with IRAS Sky Survey Atlas (ISSA) images at 100 μm. Molecular emission of the target area is found to be very extended and is well matching with the FIR emission boundary. There are several pieces of clouds, and as some of spectra show several peaks, there seem to be several clouds overlapped in some directions. The Velocity of Local Standard of Rest (VLSR) of the CO emission of the mapped region ranges from -20 to +10 km/s. It is also found that the two cloudlets located around I = 180° have VLSR = -20 km/s, which is very abnormal. The peak antenna temperature of 13 K arises near the H II Region S241.