Multi-frequency measurements of the NVSS foreground sources in the cosmic background imager fields
Context. We present the results of the flux density measurements at 4.85GHz and 10.45 GHz of a sample of 5998 NVSS radio sources with the Effelsberg 100m telescope. Aims. The initial motivation was the need to identify the NVSS radio sources that could potentially contribute significant contaminating flux in the frequency range at which the Cosmic Background Imager experiment operated. Methods. An efficient way to achieve this challenging goal has been to compute the high frequency flux density of those sources by extrapolating their radio spectrum. This is determined by the three-point spectral index measured on the basis of the NVSS entry at 1.4GHz and the measurements at 4.85 GHz and 10.45GHz carried out with the 100m Effelsberg telescope. Results. These measurements are important since the targeted sample probes the weak part of the flux density distribution, hence the decision to make the data available. Conclusions. We present the table with flux density measurements of 3434 sources that showed no confusion allowing reliable measurements, their detection rates, their spectral index distribution and an interpretation which explains satisfactorily the observed uncertainties.
Additional Information© ESO 2009. Received 31 October 2008. Accepted 14 April 2009. The authors would like to thank the anonymous referee for the comments that significantly improved the content of the manuscript. Furthermore, we want to thank the internal referee Dr D. Graham also for his comments and suggestions. We would like to acknowledge the help of Dr I. Agudo, Mrs S. Bernhart, Dr V. M. C. Impellizzeri and Dr R. Reeves and all the operators at the 100m telescope for their help with the observations. The author was mostly financed by EC funding under the contract HPRN-CT-2002-00321 (ENIGMA) and completed this work as member of the International Max Planck Research School (IMPRS) for Radio and Infrared Astronomy. All the results presented here have been based on observations with the 100m telescope of the MPIfR (Max-Planck-Institut für Radioastronomie).
Published - Angelakis2009p5236Astron_Astrophys.pdf