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Paper: Observations and Analysis of 1-22 GHz Instantaneous Spectra for 54 BL Lacertae Objects in 1997-1998
Volume: 159, BL Lac Phenomenon
Page: 69
Authors: Kovalev, Yuri Y.; Bogdantsov, A. V.
Abstract: The new results of the instantaneous spectra observations at 31, 13, 7.6, 3.9, 2.7 and 1.4~cm for 50 BL Lacertae objects, carried out from March, 1997, to April, 1998, at the radio telescope RATAN-600 are reported. These observations represent the part of our monitoring program studying the long term spectra variability of compact extragalactic radio sources (the total list contains now about 550 objects with declinations of -30^circ dev + 42^circ). We discuss and compare spectral properties and variability for the samples of BL Lacs, HPQs, LPQs, and radio galaxies. For example, we infer that the distributions of spectral parameters are nearly the same for BL Lacs and quasars (K-S test) but the constructed "averaged" spectrum of BL Lacs is flatter than that of quasars and radio galaxies. We conclude that the same basic physical model can be applied to the emission of BL Lacs and quasars in the considered frequency range, with the commonly suggested difference that probably BL Lacs' jet axes are systematically more aligned with the line of sight.
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