Markarian 421, a BL Lac object, is currently undergoing a bright X-ray flare. We have reported the news to Astronomers Telegram #2444. Following is the posted text.
MAXI/GSC has detected a bright X-ray flare from a BL Lac object Mrk 421. Its X-ray flux increased to 156 +- 11 mCrab (1.5 – 10 keV) on 2010 February 16 (mid MJD = 55243.5) from <30 mCrab on 2010 February 14. The current flux is higher than that in the recent bright X-ray flare reported by MAXI on 2010 January 01 (116 +- 10 mCrab, ATEL #2368). Multiwavelength observations of this source are encouraged.
The latest light curve and image of this source are available at the following URL: http://maxi.riken.jp/sourcelist.html.