X-ray flaring activity on the gamma-ray blazar S5 0716+714 detected by Swift

ATel #6086; A. Stamerra (INAF Torino & SNS Pisa), L. Pacciani (INAF-IAPS Roma), P. Da Vela (Univ. of Siena), E. Lindfors (Tuorla Observatory), D. Mazin (MPI-Muenchen), J. Sitarek (IFAE-Barcelona)
on 21 Apr 2014; 17:54 UT
Credential Certification: Antonio Stamerra (antonio.stamerra@to.infn.it)

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The XRT instrument aboard the Swift observatory measured an enhanced activity from the low-frequency gamma-ray blazar 0716+714 (RA= 07:21:53, DEC=+71:20:36 in J2000, estimated redshift z~0.31, Nilsson et al. 2008, A&A 487, L29 and Danforth et al. 2013, A&A 764, 57). Quicklook analysis indicates that the source on April 21st, 2014, was detected in high state in the 0.2-10 keV range, with an average count rate ~1.1 cps (count per seconds). Observations on April 17th and 18th revealed a fast variability with the count rate dropping from 0.8 cps to 0.2 in less than 12 hours, as reported in http://www.swift.psu.edu/monitoring/source.php?source=S50716+714
Preliminary analysis of XRT data in Photon Counting mode, without pile-up correction, shows two clear outbursts on April 17th and April 21st, corresponding to a flux 0.5-5 keV up to (22.5 +/- 0.6)E-12 erg/cm2/s, approximately 4-5 times higher than the quiescent flux. Interestingly the Swift observation on April 18th, 10 hours after the previous one, shows a much lower flux around (4.0+/-0.5)e-12 erg/cm2/s.

Preliminary analysis of UVOT data shows the source at approximately 0.5 mag brighter in the V-UV band respect to the monitoring in previous months, nonetheless dimmer than previous optical outbursts (e.g. in 2011 ATel#3700). Daily variability is clearly detectable. Preliminary magnitudes in the V and U band during last week, not corrected for interstellar reddening, are listed (AB system):