A1 Refereed original research article in a scientific journal
37 GHz observations of a large sample of BL lacertae objects
Authors: Nieppola E, Tornikoski M, Lahteenmaki A, Valtaoja E, Hakala T, Hovatta T, Kotiranta M, Nummila S, Ojala T, Parviainen M, Ranta M, Saloranta PM, Torniainen I, Troller M
Publisher: UNIV CHICAGO PRESS
Publication year: 2007
Journal:: Bulletin of the American Astronomical Society
Journal name in source: ASTRONOMICAL JOURNAL
Journal acronym: ASTRON J
Volume: 133
Issue: 5
First page : 1947
Last page: 1953
Number of pages: 7
ISSN: 0004-6256
DOI: https://doi.org/10.1086/512609
Abstract
We present 37 GHz data obtained at Metsahovi Radio Observatory from 2001 December to 2005 April for a large sample of BL Lacertae objects. We also report the mean variability indices and radio spectral indices in frequency intervals 5-37 and 37-90 GHz. Approximately 34% of the sample was detected at 37 GHz, 136 BL Lacertae objects in all. A large majority of the detected sources were low-energy BL Lac objects. The variability index values of the sample were diverse, the mean fractional variability of the sample being Delta S-2 = 0.31. The spectral indices also varied widely, but the average radio spectrum of the sample sources is flat. Our observations show that many of the high-energy BL Lac objects, which are usually considered radio-quiet, can at times be detected at 37 GHz.
We present 37 GHz data obtained at Metsahovi Radio Observatory from 2001 December to 2005 April for a large sample of BL Lacertae objects. We also report the mean variability indices and radio spectral indices in frequency intervals 5-37 and 37-90 GHz. Approximately 34% of the sample was detected at 37 GHz, 136 BL Lacertae objects in all. A large majority of the detected sources were low-energy BL Lac objects. The variability index values of the sample were diverse, the mean fractional variability of the sample being Delta S-2 = 0.31. The spectral indices also varied widely, but the average radio spectrum of the sample sources is flat. Our observations show that many of the high-energy BL Lac objects, which are usually considered radio-quiet, can at times be detected at 37 GHz.
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