37 GHz observations of a large sample of BL Lacertae objects
Abstract
We present 37 GHz data obtained at Metsahovi Radio Observatory in 2001 December - 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 GHz 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 Lacs (LBLs). 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 Lacs (HBL), which are usually considered radio-quiet, can at times be detected at 37 GHz.
Keywords
Cite
@article{arxiv.0705.0887,
title = {37 GHz observations of a large sample of BL Lacertae objects},
author = {E. Nieppola and M. Tornikoski and A. Lähteenmäki and E. Valtaoja and T. Hakala and T. Hovatta and M. Kotiranta and S. Nummila and T. Ojala and M. Parviainen and M. Ranta and P. -M. Saloranta and I. Torniainen and M. Tröller},
journal= {arXiv preprint arXiv:0705.0887},
year = {2010}
}
Comments
12 pages, 5 figures + 5 tables. Published in Astronomical Journal