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1ES 1959+650 Very Bright in X-Rays Again

ATel #9949; Bidzina Kapanadze (Abastumani Astrophysical Observatory at Ilia State University, Tbilisi, Georgia)
on 7 Jan 2017; 10:46 UT
Credential Certification: Bidzina Kapanadze (bidzina_kapanadze@iliauni.edu.ge)

Subjects: X-ray, Blazar

Referred to by ATel #: 10430, 10514, 10622, 10743

Since 2015 August, the nearby TeV-detected HBL source 1ES 1959+650 (z=0.048) is in a phase of enhanced X-ray activity compared to the previous years (Kapanadze et al. 2016, MNRAS, 461, L26; ATel #8014,#8289,#8342,#8468,#9121,#9205,#9694). During the last five Swift observations of 1ES 1959+650 (performed in the framework of our ToO requests Number 8721 and 8827), the 0.3-10 keV count rate has increased by factor of 3 as follows: 2016 December 18 6.92+/-0.09 cts/s; 2016 December 21 7.38+/-0.07 cts/s; 2016 December 29 12.80+/-0.10 cts/s; 2017 January 1 13.43+/-0.10 cts/s; 2017 January 7 20.78+/-0.19 cts/s; Note that the later value is only by 16% smaller than highest historical 0.3-10 keV flux recorded on 2016 July 2 in the framework of our ToO observations (Request Number 8261) and a factor of 2.83 larger than the weighted mean rate from all XRT observations of this source. In the framework of one-zone SSC models, an enhanced activity is also expected in the UV-radio and gamma-ray parts of the spectrum, and intensive multiwavelength observations of 1ES 1959+650 are strongly encouraged to study instable processes and emission mechanisms in this source.