A new highest historical X-ray State in 1ES 1959+650
ATel #9205; Bidzina Kapanadze (Abastumani Astrophysical Observatory at Ilia State University, Tbilisi, Georgia), Daniela Dorner (University of Wuerzburg, Germany), Sergo Kapanadze (Abastumani Astrophysical Observatory at Ilia State University, Tbilisi, Georgia)
on 3 Jul 2016; 16:01 UT
Credential Certification: Bidzina Kapanadze (bidzina_kapanadze@iliauni.edu.ge)
Subjects: X-ray, AGN, Blazar
The nearby HBL source 1ES 1959+650 (z=0.047) shows a prolonged strong X-ray flaring activity since 2016 May 6, observed by X-ray Telescope onboard the Swift satellite (Swift-XRT) mostly in the framework of our Target of Opportunity (ToO) requests of different urgencies (ToO Request Number: 8051, 8099, 8178, 8192, 8204, 8224, 8230, 8257, 8261). In this period, the 0.3-10 keV count rate has shown a variability by a factor of 4.4, and the long-term flare was superimposed by shorter-term, lower-amplitude flares when the count rate exceeded the level of 20 cts/s four times. During the last flare starting on June 30, the count rate has doubled in about 1.4 day to 24.76+/-0.25 cts/s (recorded on July 2) which is the highest historical value since the start of the Swift observations of 1ES 1959+650 (2005 April 19). The 0.3-10 keV spectrum from this observation is described well by the logparabola model with the photon index at 1 keV a=1.77(0.03), curvature parameter b=0.13+/-0.04, the position of the synchrotron SED Ep=7.67+/-0.38 keV which is the largest value ever reported for this source. The unabsorbed 0.3-10 keV flux amounted (1.08+/-0.02)\times 10^{-9} erg/cm^2/s that is by 28% larger than the previous highest historical 0.3-10 keV flux recorded on 2015 December 26 (Kapanadze B., Dorner D., Vercellone S. et al. 2016, MNRAS, 461, L26). Unfortunately, 1ES 1959+650 can not be observed by Swift between July 3 and July 10 due to the pole constraint for Swift. Therefore, the further intensive multiwavelength observations of this HBL are strongly encouraged.
