The 72-h WEBT microvariability observation of blazar S5 0716 + 714 in 2009^⋆

¹ Florida International University, 11200 SW 8th St, Miami, FL 33199, USA
e-mail: gopalbhatta716@gmail.com
² Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shosse Blvd., 1784 Sofia, Bulgaria
³ Max-Plank-Institut fur Radioastromomie Auf dem Huegel 69, 53121 Bonn, Germany
⁴ Astronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, Russia
⁵ Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA
⁶ Observatorio Astronomico della Regione Autonoma Valle d’Astoa, Italy
⁷ Armenzano Astronomical Observatory, 06081 Assisi, Italy
⁸ EPT Observatories, Tijarafe, La Palm, Spain
⁹ INAF, TNG Fundacion Galileo Galilei, Rambla José Ana Fernández Perez 7, 38712 Breña Baja, La Palma, Spain
¹⁰ Abastumani Observatory, Mt. Kanobili, 0301 Abatsumani, Georgia
¹¹ Cork, Ireland
¹² INAF, Osservatorio di Torino, via Osservatorio 20, 10025 Pino Torinese, Torino, Italy
¹³ Crimean Astrophysical Observatory, Crimea, Ukraine
¹⁴ Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, 263 129 Nainital, India
¹⁵ School of Space Science and Physics, Shandong University, Weihai 264209, PR China
¹⁶ Engelhardt Astronomical Observatory, Kazan Federal University, Tatarstan, Russia
¹⁷ Landessternwarte Heidelberg-Königstuhl, Germany
¹⁸ Issac Newton Institute of Chile, 198504 St.-Petersburg Branch, Russia
¹⁹ Korea Astronomy and Space Science Institute, 305-348 Daejeon, Republic of Korea
²⁰ Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
²¹ Butler University, Indianapolis Indiana, 4600 Sunset Ave, Indianapolis, IN 46208, USA
²² Astronomie Stiftung Tebur, Fichtenstrasse 7, 65468 Trebur, Germany
²³ Hankasalmi Observatory, Vertaalantie 419, 40270 Jyväskylän, Finland
²⁴ Jakokoski Observatory, Finland
²⁵ Dark Sky Observatory, Applachian State University, USA
²⁶ Guadarrama Observatory, Camino Bajo del Castillo s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Cañada, Madrid, Spain
²⁷ Agrupacio Astronomica de Sabadell, Carrer Prat de la Riba, 08206 Sabadell, Barcelona, Spain
²⁸ MPC-442 Gualba Observatory, Barcelona, Spain
²⁹ Florida Institute of Technology, 150 West University Boulevard Melbourne, FL 32901, Melbourne, Florida, USA
³⁰ National Astronomical Observatories, CAS, PR China
³¹ Department of Astronomy , Beijing Normal University, Muduo Rd, Haidian, Beijing, PR China
³² Centre for Space Research, North-WestUniversity, Potchefstroom, South Africa

Received: 15 August 2012
Accepted: 24 July 2013

Abstract

Context. The international Whole Earth Blazar Telescope (WEBT) consortium planned and carried out three days of intensive micro-variability observations of S5 0716 + 714 from February 22, 2009 to February 25, 2009. This object was chosen due to its bright apparent magnitude range, its high declination, and its very large duty cycle for micro-variations.

Aims. We report here on the long continuous optical micro-variability light curve of 0716+714 obtained during the multi-site observing campaign during which the Blazar showed almost constant variability over a 0.5 mag range. The resulting light curve is presented here for the first time. Observations from participating observatories were corrected for instrumental differences and combined to construct the overall smoothed light curve.

Methods. Thirty-six observatories in sixteen countries participated in this continuous monitoring program and twenty of them submitted data for compilation into a continuous light curve. The light curve was analyzed using several techniques including Fourier transform, Wavelet and noise analysis techniques. Those results led us to model the light curve by attributing the variations to a series of synchrotron pulses.

Results. We have interpreted the observed microvariations in this extended light curve in terms of a new model consisting of individual stochastic pulses due to cells in a turbulent jet which are energized by a passing shock and cool by means of synchrotron emission. We obtained an excellent fit to the 72-hour light curve with the synchrotron pulse model.