Blazar Optical Sky Survey (BOSS) Project

Blazar Optical Sky Survey (BOSS) Project

Blazar Optical Sky Survey (BOSS) Project is an optical monitoring program, initiated on April 2013 by Dr. Kosmas Gazeas at the University of Athens. It aims at monitoring the optical variability on active Blazars, in parallel with other multi-wavelength observations obtained from space and ground-based observatories.

Blazar variability timescales are often divided into three categories: the intra-day variability (IDV) which ranges between a few minutes up to one day (Wagner & Witzel 1995), the short-term variability (STV) which ranges between a few days to a few months and the long-term variability (LTV), which covers all variations longer than a few months, up to several years (Gupta et al. 2004).


BOSS Project utilizes the 0.40 m f/8 robotic and remote controlled telescope at the University of Athens Observatory, which is equipped with a ST10 XME CCD camera and a UBVRI filter set (Bessell specifications). Continuous observations every night are not always easy to occur, mainly due to weather conditions.

The University of Athens Observatory with telescope and instruments inside the dome.

Team members

BOSS Project is a collaboration between the University of Athens (Greece) and several other Institutes worldwide. Among them, the major collaborators are:

  • Kosmas Gazeas, Apostolos Mastichiadis
  • University of Athens, GR 15784 Zografos, Athens, Greece
  • Maria Petropoulou
  • Purdue University, West Lafayette, Indiana, IN 47907-2036, USA
  • George Vasilopoulos
  • Max-Planck-Institut für extraterrestrische Physik, Garching bei Muenchen, D-85741, Germany
  • Stazsek Zola, Gopal Bhatta, Arti Goyal
  • Astronomical Observatory of the Jagiellonian University, Krakow, ul. Orla, 30-244, Poland
  • Walter Max-Moerbeck
  • National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801, USA
  • Talvikki Hovatta
  • Aalto University, Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
  • Daniela Dorner
  • Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Germany

  • Sample Light Curves

    The photometric light curves of Mrk421 in all optical bands. Gray areas mark the periods of brightness peak, while the width of each box represents the duration of each peak and the dashed line the day of maximum brightness.

    Continuous monitoring of Mrk421 for a total of 370 days (2013-2014) in R-band. Luminosity variations of this highly active blazar can be cross-correlated with orbital data and/or other monitoring campaigns in a wider range of energies.

    Multiband sample of Mrk421 data, spreading over the entire electromagnetic spectrum from very high energies (gamma rays on top) to very low ones (radio signal at bottom). Vertical dashed lines on the left represent the moment when the high energy flare occurred on 12 April 2013 (MJD 56394) and the corresponding signals detected a few days later in lower energies. Time lag is detected after comparing these signals, as a result of electron cooling mechanism.

    Target list

    In the frame of BOSS Project, the following targets are under monitoring schedule:


    Publications and scientific announcements released after the results of BOSS Projects are:

  • Gazeas, K.; Petropoulou, M.; Mastichiadis, A., 2013, Continuous optical monitoring of the highly active blazar Mrk421, Hellenic Conference, 30G

  • Gazeas, K.; Max-Moerbeck, W.; Petropoulou, M.; Hovatta, T.; Vasilopoulos, G.; Mastichiadis, A., 2015, Multi-wavelength monitoring of the highly active blazar Mrk421, Investigating the high vs. low energy correlated variability, Hellenic Conference, (in press)

  • Zola, S.; Valtonen, M.; Bhatta, et al. (Gazeas, K. co-author), A Search for QPOs in the Blazar OJ287: Preliminary Results from the 2015/2016 Observing Campaign, 2016, Galaxy, 4, 41

  • Bhatta, G.; Zola, S.; Stawarz, L. et al. (Gazeas, K. co-author), Detection of Possible Quasi-periodic Oscillations in the Long-term Optical Light Curve of the BL Lac Object OJ 287, 2016, arXiv: 1609.02388

  • Valtonen, M. J.; Zola, S.; Ciprini, et al. (Gazeas, K. co-author), Primary Black Hole Spin in OJ 287 as Determined by the General Relativity Centenary Flare, 2016, ApJ, 819L, 37


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