464 citations · 9.7k across the 212 of their papers we have counts for
12 papers · 1 filter
Doppler factors, Lorentz factors and viewing angles for quasars, BL Lacertae objects and radio galaxies
T. Hovatta, E. Valtaoja, M. Tornikoski +1
We have calculated variability Doppler boosting factors, Lorentz factors, and viewing angles for a large sample of sources by using total flux density observations at 22 and 37 GHz…
Long term radio variability of AGN
T. Hovatta, M. Tornikoski, H. J. Lehto +7
A large number of AGN have been monitored for nearly 30 years at 22, 37 and 87 GHz in Metsähovi Radio Observatory. These data were combined with lower frequency 4.8, 8.0 and 14.5 G…
Wavelet analysis of a large sample of AGN at high radio frequencies
T. Hovatta, H. J. Lehto, M. Tornikoski
We have studied the characteristic timescales of 80 AGNs at 22, 37 and 90 GHz examining the properties of the wavelet method and comparing them to traditional Fourier-based methods…
Long-term radio variability of AGN: flare characteristics
T. Hovatta, E. Nieppola, M. Tornikoski +3
We have studied the flare characteristics of 55 AGN at 8 different frequency bands between 4.8 and 230 GHz. Our extensive database enables us to study the various observational pro…
Blazar sequence - an artefact of Doppler boosting
E. Nieppola, E. Valtaoja, M. Tornikoski +2
The blazar sequence is a scenario in which the bolometric luminosity of the blazar governs the appearance of its spectral energy distribution. The most prominent result is the sign…
Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006--2007 outburst
C. M. Raiteri, M. Villata, V. M. Larionov +2
The blazar AO 0235+164 was claimed to show a quasi-periodic behaviour in the radio and optical bands. Moreover, an extra emission component contributing to the UV and soft X-ray fl…
WEBT and XMM-Newton observations of 3C 454.3 during the post-outburst phase. Detection of the little and big blue bumps
C. M. Raiteri, M. Villata, V. M. Larionov +3
The blazar 3C 454.3 underwent an unprecedented optical outburst in spring 2005. This was first followed by a mm and then by a cm radio outburst, which peaked in February 2006. We r…
The WEBT Campaign on the Blazar 3C279 in 2006
M. Boettcher
The quasar 3C279 was the target of an extensive multiwavelength monitoring campaign from January through April 2006, including an optical-IR-radio monitoring campaign by the Whole…
Statistical analyses of long-term variability of AGN at high radio frequencies
T. Hovatta, M. Tornikoski, M. Lainela +5
We present a study of variability time scales in a large sample of Active Galactic Nuclei at several frequencies between 4.8 and 230 GHz. We investigate the differences of various…
37 GHz observations of a large sample of BL Lacertae objects
E. Nieppola, M. Tornikoski, A. Lähteenmäki +11
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…
IX Russian-Finnish Symposium on Radio Astronomy "Multi-wavelength investigations of solar and stellar activity and active galactic nuclei"
V. E. Abramov-Maximov, T. G. Arshakian, V. M. Bogod +33
The IX Russian-Finnish Symposium on Radio Astronomy was held in Special astrophysical observatory RAS in Nizhnij Arkhyz, Russia on 15-20 October 2006. It was dedicated to the two-s…
Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71. I. Simultaneous broadband observations during November 2003
L. Ostorero, S. J. Wagner, J. Gracia +6
Some intra-day variable, compact extra-galactic radio sources show brightness temperatures severely exceeding 10^{12} K, the limit set by catastrophic inverse-Compton (IC) cooling…