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Optical rebrightening of the blazar S5 0716+714

ATel #11339; Alessandro Marchini (Astronomical Observatory, Department of Physical Sciences, Earth and Environment (DSFTA), University of Siena - Italy), Giacomo Bonnoli, Vincenzo Millucci, Bartolomeo Trefoloni (DSFTA, University of Siena - Italy)
on 23 Feb 2018; 14:18 UT
Credential Certification: Giacomo Bonnoli (giacomo.bonnoli@unisi.it)

Subjects: Optical, Blazar

We report that the photometric follow-up of the current active phase (see ATel #11100,#11107) of the blazar S5 0716+714 (RA: 7:21:53.45, Dec: 71:20:36.36, J2000.0) that we are pursuing at the Astronomical Observatory of the University of Siena may indicate a new rising phase for the optical brightness of the source, with the R-band Vega magnitude dropping below R=12.5 on Feb 19.98, while at the beginning of January the source had faded to R~13.2. However our sampling has been hampered by recurrent bad weather and we can not infer any firm conclusion on the actual trend from our sparse data set. The results of our observations are summarized in the following table:

Civil Date (UT) Rmag dRmag
2017 Dec 28.91 R=12.76 0.01
2017 Dec 29.87 R=12.76 0.01
2018 Jan 02.75 R=13.19 0.01
2018 Feb 08.77 R=12.71 0.01
2018 Feb 09.89 R=12.92 0.01
2018 Feb 19.98 R=12.47 0.01

Observations for each available night consist of 4 x 300 s exposures in the Johnson-Cousins R filter, taken in 2x2 binning under good observing conditions with clear sky. Seeing ranged between 4.5" and 5" (FWHM). After dark current subtraction and flat field correction the images for each night were averaged and aperture photometry was performed on the average frame by means of the MaximDL software package. Reference and check stars in the field of view were taken from the finding chart made available by Landessternwarte Koenigstuhl at https://www.lsw.uni-heidelberg.de/projects/extragalactic/charts/0716+714.html . The reference R magnitudes for these stars are taken from Villata et al., A&AS 130, 305 (1998). Quoted uncertainty is statistical only. We will continue monitoring the source in the following nights. Multi-wavelength follow-up is encouraged.

Any enquiry on these observations can be addressed either to Alessandro Marchini (alessandro.marchini@unisi.it) or to Giacomo Bonnoli (giacomo.bonnoli@unisi.it).

The Astronomical Observatory of the University of Siena runs a remotely operated 0.3 m f/5.6 Maksutov-Cassegrain reflector, installed on a German equatorial mount. The instrument is hosted in a dome on the roof of the Department building, 0.7 km southwards of the city center (43 18 45 N 11 20 12 E). Site elevation is around 300 m above sea level. The telescope is equipped with a Johnson-Cousins BVRI filter wheel and a STL-6303 SBig CCD (3072 x 2048 9 micron pixels) capable of imaging a 58 x 38 square arcminutes field of view with a resolution of 2.3"/pixel (in binning 2x2).