Single-Dish Performance of KVN 21 m Radio Telescopes: Simultaneous Observations at 22 and 43 GHz
Abstract
We report simultaneous multifrequency observing performance at 22 and 43 GHz of the 21 m shaped-Cassegrain radio telescopes of the Korean VLBI Network (KVN). KVN is the first millimeter-dedicated VLBI network in Korea having a maximum baseline length of 480 km. It currently operates at 22 and 43 GHz and is planned to operate in four frequency bands: 22, 43, 86, and 129 GHz. The unique quasi optics of KVN enable simultaneous multifrequency observations based on efficient beam filtering and accurate antenna-beam alignment at 22 and 43 GHz. We found that the offset of the beams is within less than 5‧‧ over all pointing directions of the antenna. The dual-polarization, cooled, high electron mobility transistor (HEMT) receivers at 22 and 43 GHz result in receiver noise temperatures less than 40 K at 21.25-23.25 GHz and 80 K at 42.11-44.11 GHz. The pointing accuracies have been measured to be 3‧‧ in azimuth and elevation for all antennas. The measured aperture efficiencies are 65%(K)/67%(Q), 62%(K)/59%(Q), and 66%(K)/60%(Q) for the three KVN antennas, KVNYS, KVNUS, and KVNTN, respectively. The main-beam efficiencies are measured to be 50%(K)/52%(Q), 48%(K)/50%(Q), and 50%(K)/47%(Q) for KVNYS, KVNUS, and KVNTN, respectively. The estimated Moon efficiencies are 77%(K)/90%(Q), 74%(K)/79%(Q), and 80%(K)/86%(Q) for KVNYS, KVNUS, and KVNTN, respectively. The elevation dependence of the aperture efficiencies is quite flat for elevations greater than 20°.
- Publication:
-
Publications of the Astronomical Society of the Pacific
- Pub Date:
- December 2011
- DOI:
- 10.1086/663326
- arXiv:
- arXiv:1110.3881
- Bibcode:
- 2011PASP..123.1398L
- Keywords:
-
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- 33 pages, 10 figures, 9 tables, Accepted for publication in PASP