The SAW CZT-based spectrometer was used for the first time in radio astronomy as a spectral analyzing device. The early experimental observations were carried out at the 13.7 m radio telescope at Qinghai station of the Purple Mountain Astronomical Observatory (Chen et al. 1991). Since then the digital processor in the spectrometer has been improved. The 13 mm spectral receiving system on the 25 m radio telescope at Urumqi was experimentally used to observe H2O masers in order to continue to testing the feasibility of SAW CZT-based spectrometer for astronomical applications. We observed water vapor maser emission from a number of Galactic sources. To compare with previous observations, the observed lines from some well known sources, such as W49, Orion , W3(OH) and DDG25 are shown in Fig. 4. We estimate that the individual channel sensitivity had typically 7 Jy in the 240 s integrated time. The spectral features for individual sources are consistent with those published in previous paper (e.g. Comoretto et al. 1990). These results demonstrate the feasibility of the SAW CZT-based spectrometer for astronomical spectral line observations. At the same time, the data confirm the excellent meteorological quality of the Urumqi Station for short center-meter astronomical observations.
We thank Paul T.P. Ho and Philip C. Myers, scientists in the Harvard-Smithsonian Center for Astrophysics, U.S.A., who first encouraged this project and have been continuously supporting it with their helpful suggestions. This program is financially supported by funds from the Chinese National Science Foundation and the Joint Laboratory of radio Astronomy in the Academy of Sciences of China.
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