EDP Sciences
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Volume 368, Number 2, March III 2001
Page(s) 431 - 439
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20010029

A&A 368, 431-439 (2001)
DOI: 10.1051/0004-6361:20010029

Search for new flat-spectrum radio sources

H. Teräsranta1, S. Urpo1, S. Wiren2 and M. Valtonen2

1  Metsähovi radio research station, Helsinki University of Technology, 02540 Kylmälä, Finland
2  Tuorla Observatory, 21500 Piikkiö, Finland

(Received 15 November 2000 / Accepted 19 December 2000)

22 GHz continuum observations with the Met sähovi Radio telescope are used to identifying new flat spectrum radio sources selected from lower frequency survey data. The sample is complete to sources with a flux higher than 0.5 Jy at 1.4 GHz, $\alpha \ge -0.5$ between 1.4 and 4.85 GHz, declination from 0 to +75 degrees and sources more than 20o from the galactic plane. Additional strong sources from the 5 GHz survey were observed to get the sample as complete as possible down to 1.0 Jy at 22 GHz for extrapolation of source counts to lower flux levels. The new flat spectrum sources will be added to our monitoring sample and their duty cycle will be studied for the coming $\gamma$-ray observatiories AGILE and GLAST.

Key words: galaxies: active -- BL Lacertae objects: general -- quasars: general -- radio continuum: galaxies -- radio continuum: general

Offprint request: H. Teräsranta, hte@alpha.hut.fi

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© ESO 2001