Swift/BAT detects an outburst from UX Ari
ATel #5907; H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), W. Baumgartner (CRESST/GSFC/UMBC), J. Cummings (CRESST/GSFC/UMBC), N. Gehrels (GSFC), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. Palmer (LANL), T. Sakamoto (Aoyama Gakuin Univ.), M. Stamatikos (OSU/GSFC), T. Ukwatta (MSU)
on 20 Feb 2014; 13:35 UT
Credential Certification: Hans A. Krimm (Hans.Krimm@nasa.gov)
Subjects: X-ray, Star, Variables
The RS Canum Venaticorum type variable star UX Ari is currently in outburst as detected in the Swift/BAT hard X-ray transient monitor in the 15-50 keV band. The current outburst began on 2014 February 14 (MJD 56702) when it had a count rate of 0.004 +/- 0.002 ct/s/cm^2 (~20 mCrab). It continued to brighten, reaching a rate of 0.013 +/- 0.003 ct/s/cm^2 (~60 mCrab) on 2014 February 17. It has since faded somewhat, with a rate of 0.005 +/- 0.002 ct/s/cm^2 (~20 mCrab) on 2014 February 19. Although the source has had short (~one day) flares above 30 mCrab before (see details below), this is the longest bright sustained outburst from this source yet observed in the BAT monitor.
The four earlier episodes above 30 mCrab were:
2009 February 13 (MJD 54875): 0.014 +/- 0.004 (65 mCrab)
2011 September 15 (MJD 55819): 0.008 +/- 0.002 (35 mCrab)
2012 January 7 (MJD 55933): 0.009 +/- 0.001 (40 mCrab)
2012 September 7 (MJD 56177): 0.008 +/- 0.002 (35 mCrab)
Swift/BAT transient monitor light curve for UX Ari
