The Highest Historical X-Ray Flux from HBL Source MS1221.8+2452
ATel #5841; Bidzina Kapanadze (Ilia State University, Tbilisi, Georgia)
on 31 Jan 2014; 19:23 UT
Credential Certification: Bidzina Kapanadze (bidzina_kapanadze@iliauni.edu.ge)
We report the highest historical X-ray flux in the high energy peaked BL Lacertae source MS1221.8+2452 (z=0.218 ) through the 0.3-10 keV energy band detected by the X-ray Telescope (XRT) onboard the Swift satellite which observed the source 3 times during January 30-31 (total exposure time - about 4.5 hr). Using the data provided at http://www.swift.psu.edu/monitoring/ , we have found that the object showed the 0.3-10 keV flux of 1.23+/-0.03 cts/s during the first observation of January 30 which is with 13% higher compared to the highest flux recorded during previous observations. It was found as high as 2.27+/-0.31 cts/s at the beginning of the second pointing performed on January 30 and the source then showed a fast flux variability (with a decaying trend) at 3 sigma confidence with fractional rms variability amplitude of 14% within 5 ks. The observation-binned flux is with a factor 16 higher compared to the lowest historical flux of 0.10+/-0.1 cts/s recorded on 2013 March 10. In the framework of one-zone SSC model, an increased activity is also expected in the UV-radio and gamma-ray bands. Therefore, we strongly encourage the intensive multiwavelength observations of MS1221.8+2452 as with the ground-based telescopes as by means of the different space missions.
