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The blazar S5 0716+714 doubled its R-band optical flux since the beginning of December

ATel #12298; Alessandro Marchini (Astronomical Observatory, Department of Physical Sciences, Earth and Environment (DSFTA), University of Siena - Italy), Giacomo Bonnoli, Lorenzo Bellizzi, Paolo Da Vela, Vincenzo Millucci, Riccardo Paoletti, Leonardo Stiaccini, Stefano Truzzi, Sofia Ventura (DSFTA, University of Siena - Italy)
on 14 Dec 2018; 18:57 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Giacomo Bonnoli (giacomo.bonnoli@unisi.it)

Subjects: Optical, Blazar

Referred to by ATel #: 12682, 16980

We report our last photometric measurement of the blazar S5 0716+714 (RA: 7 21 53.45 Dec: 71 20 36.36 J2000.0) obtained about two hours ago (Dec 14.72): the source reached the R-band optical magnitude R=12.77(0.01). The blazar showed frequent and intense optical activity along the last year (see ATel #11107,#11339,#11676,#11725) and we are monitoring it from the Astronomical Observatory of the University of Siena since the unprecedented flare in VHE gamma rays reported by the MAGIC Collaboration in December 2017 (ATel #11100). This observation was performed within the frame of a guidance project about astrophysics involving high school students from the "Liceo Scientifico A. Poliziano" (Montepulciano, SI) and "Liceo Scientifico Roncalli" (Poggibonsi, SI).
The following table gathers our recent measurements:

Civil Date (UT) Rmag(dRmag)
2018 Nov 09.12 13.93(0.01)
2018 Nov 15.11 13.44(0.01)
2018 Dec 05.72 13.48(0.01)
2018 Dec 14.72 12.77(0.01)

Although the source is still far from the brightest R-band optical state measured along our campaign (R=12.16, ATel #11676), from the brightest state reported in 2018 (R=11.98, ATel #11725) or from the historical record (R=11.65, ATel #6953) the doubling of the flux in few days may hint to a new active phase.

Details of the observations and of the photometric analysis follow closely those reported in our previous ATels regarding this source (see e.g. ATel #11339). A brief description of the instrumental setup is available there as well. We acknowledge excellent scientific cooperation with, and valuable support from, the WEBT Collaboration and the MAGIC Collaboration.

Any enquiry on these observations can be addressed either to Alessandro Marchini (alessandro.marchini@unisi.it) or to Giacomo Bonnoli (giacomo.bonnoli@unisi.it). We will continue monitoring the source in the following nights. Multi-wavelength follow-up is encouraged.

We thank all the involved high school students for their enthusiastic participation in the observations and photometric analyses performed along their guidance project: M. Argiolas, A. Avignonesi, R. Baldeschi, V. Bastreghi, L. Beati, G. Benedetti, A. Bors, L. Chierchini, M. Faillaci, A. Falcone, G. Leti, I. Maramai, G. Mesina, F. Nespolo, N. Picchiarelli, S. Peruzzi, L. Pierguidi, E. Pucci, J. P. Savino.

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