Title :
A 45-m telescope with a surface accuracy of 65 μm
Author :
Ukita, Nobuharu ; Tsuboi, Masato
Author_Institution :
Nobeyama Radio Obs., Nagano, Japan
fDate :
5/1/1994 12:00:00 AM
Abstract :
The Nobeyama 45-m telescope has been upgraded for higher frequency and higher sensitivity observations. The surface accuracy of the antenna was improved from 0.2 mm rms to 65 μm rms using a radio holography method at the prime focus. Pointing accuracy was also improved by replacing a large Gregorian subreflector cabin with a smaller cassegrain subreflector in 1985 to reduce wind loading effects, and by installation of a new master collimator with multi-pole resolvers which were calibrated to an accuracy of 0.4 arcsec rms in 1988. Four SIS receivers using Nb/AlOx/Nb array junctions are now available on the telescope for 40, 80, 100, and 150-GHz bands. These receivers achieved quite low noise and wide-band tunability. The 2×2 multi-beam receiver for 115 GHz is very powerful for mapping observations. These improvements of telescope performance and these receivers have significantly increased the astronomical observation capability of the telescope in the wide frequency range of 40 to 150 GHz
Keywords :
microwave antennas; mixers (circuits); radio receivers; radiotelescopes; reflector antennas; surface topography measurement; 40 to 150 GHz; 45 m; EHF; Nb-AlO-Nb; Nb/AlOx/Nb array junctions; Nobeyama 45-m telescope; SIS receivers; antenna; cassegrain subreflector; mapping observations; master collimator; multipole resolvers; performance; pointing accuracy; radio holography method; surface accuracy; tunability; wind loading effects; Clouds; Collimators; Frequency; Holography; Observatories; Radio astronomy; Receivers; Surface waves; Telescopes; Wideband;
Journal_Title :
Proceedings of the IEEE