The synthesis telescope at the Dominion Radio Astrophysical Observatory

T.L. Landecker¹ - P.E. Dewdney¹ - T.A. Burgess¹ - A.D. Gray¹ - L.A. Higgs¹ - A.P. Hoffmann¹ - G.J. Hovey¹ - D.R. Karpa^1,2,3 - J.D. Lacey¹ - N. Prowse^1,4 - C.R. Purton¹ - R.S. Roger¹ - A.G. Willis¹ - W. Wyslouzil¹ - D. Routledge² - J.F. Vaneldik ²

1 - National Research Council Canada, Herzberg Institute of Astrophysics, Dominion Radio Astrophysical Observatory,
Penticton, B.C., V2A 6K3, Canada
e-mail: tom.landecker@hia.nrc.ca
2 - Electrical and Computer Engineering Department, University of Alberta, Edmonton, Alberta, T6G 2G7, Canada
3 - Present address: Rockwell Collins, Cedar Rapids, Iowa, 52498, U.S.A.
4 - Present address: NetFacet Computing Inc., 492 Fraser Ave., Ottawa, Ontario, K2A 2R2, Canada

Abstract:

We describe an aperture synthesis radio telescope optimized for studies of the Galactic interstellar medium (ISM), providing the ability to image extended structures with high angular resolution over wide fields. The telescope produces images of atomic hydrogen emission using the 21-cm Hi spectral line, and, simultaneously, continuum emission in two bands centred at 1420 MHz and 408 MHz, including linearly polarized emission at 1420 MHz, with synthesized beams of 1' and 3.4' at the respective frequencies. A full synthesis can achieve a continuum sensitivity (rms) of 0.28 mJy/beam at 1420 MHz and 3.8 mJy/beam at 408 MHz, and the 256-channel Hi spectrometer has an rms sensitivity of 3.5 $B^{-0.5}\sin\delta$ K per channel, for total spectrometer bandwidth BMHz and declination $\delta$ . The tuning range of the telescope permits studies of Galactic and nearby extragalactic objects. The array uses 9 m antennas, which provide very wide fields of view of 3.1 $^\circ$ and 9.6 $^\circ$ (at the 10% level), at the two frequencies, and also allow data to be gathered on short baselines, yielding extremely good sensitivity to extended structure. Single-antenna data are also routinely incorporated into images to ensure complete coverage of emission on all angular scales down to the resolution limit. In this paper we describe the telescope and its receiver and correlator systems in detail, together with calibration and observing strategies that make this instrument an efficient survey machine.

Key words: radio telescopes -- aperture synthesis -- wide-field imaging -- Hi spectroscopy