IAU01500
Presentation type requested: ORAL
FIRST RESULTS FROM THE 20 GHZ PILOT SURVEY FOLLOW-UP
Roberto Ricci
SISSA/ISAS (Italy)
We performed a pilot high-frequency survey (20 GHz) of 1216 deg$^{2}$ on a strip of southern sky between $\delta = -71^{\circ}$ and $-59^{\circ}$ with a rms sensitivity $\Delta$S$_{rms}$=15 mJy in order to: (a) characterize the radio source population; (b) test evolutionary models; (c) quantify the discrete source contribution to the CMB small scall fluctuations; (d) test observing strategies for a future all southern sky survey. The 20 GHz Pilot Survey utilized a novel wide band (4 GHz) analogue correlator on a ATCA 30m baseline. The antennas scanned the meridian finding a list of 574 candidate sources. In the subsequent follow-up observations 226 sources were confirmed to be real. The differential source counts of the 127 extra-galactic sources can be represented as: n(S)=70 $\times$ (S/100 mJy)$^{-2.11\pm0.24}$ Jy$^{-1}$ sr$^{-1}$ down to S$_{lim}$=100 mJy, in good agreement with the 15 GHz counts by Taylor {\it et al.} (2001). The spectral index distribution between 5 and 18 GHz of the extra-galactic sample shows that 63\% of them are ``flat''-spectrum ($\alpha_{5}^{18} > -0.5$, S$_{\nu}\propto\nu^{\alpha}$) with 22 sources having rising spectrum ($\alpha_{5}^{18} > 0$).
Ekers Ronald D, Staveley-Smith Lister , Wilson Warwick , Kesteven Micheal , Subrahmanyan Ravi , Sadler Elaine , Walker Mark , Jackson Carole , De Zotti Gianfranco
IAU XXV General Assembly | IAU216 HOME PAGE | IAU216 Speaker Program | IAU216 Poster Program