New extragalactic variable sources from an 8-GHz survey

Brandie, G. W.; Bridle, A. H.; Kesteven, Michael

doi:10.1038/252212a0

Cited by 6 publications

(1 citation statement)

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“…These sources were found to be different from those detected in low‐frequency surveys, with 70 per cent having flat or inverted spectra. More than 80 per cent had optical counterparts on the Palomar Sky Survey, most of them quasi‐stellar objects (QSOs) (Brandie & Bridle 1974; Brandie, Bridle & Kesteven 1974).…”

Section: Introductionmentioning

confidence: 99%

First results from the Australia Telescope Compact Array 18-GHz pilot survey

Ricci

Sadler

Ekers

et al. 2004

Monthly Notices of the Royal Astronomical Society

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As a pilot study for the first all‐sky radio survey at short wavelengths, we have observed 1216 deg2 of the southern sky at 18 GHz (16 mm) using a novel wide‐band (3.4‐GHz bandwidth) analogue correlator on one baseline of the Australia Telescope Compact Array. We scanned a region of sky between declination −71° and −59° with an rms noise level of 15 mJy. Follow‐up radio imaging of candidate sources above a 4σ detection limit of 60 mJy resulted in 221 confirmed detections, for which we have measured accurate positions and flux densities. For extragalactic sources, the survey is roughly 70 per cent complete at a flux density of 126 mJy and 95 per cent complete above 300 mJy. Almost half the detected sources lie within a few degrees of the Galactic plane, but there are 123 sources with |b| > 5°, which can be assumed to be extragalactic. The differential source counts for extragalactic sources in the range 0.1 Jy ≤S18 GHz≤ 3 Jy are well fitted by a relation of the form n(S) = 57 (S/Jy)−2.2±0.2 Jy−1 sr−1, in good agreement with the 15‐GHz counts published by Taylor et al. and Waldram et al. Over 70 per cent of the extragalactic sources have a flat radio spectrum (α180.843 > −0.5, Sν∝να), and 29 per cent have inverted radio spectra (α180.843 > 0). The optical identification rate is high: 51 per cent of the extragalactic sources are identified with stellar objects (candidate quasi‐stellar objects), 22 per cent with galaxies and only 27 per cent with faint optical objects or blank fields.

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Section: Introductionmentioning

confidence: 99%