Swift/BAT detects an outburst from the X-ray nova and black hole candidate GRS 1739-278

The X-ray nova and black hole candidate GRS 1739-278 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 March 9 (MJD 56725) when it had a count rate of 0.0024 +/- 0.0009 ct/s/cm^2 (~10 mCrab). It has continued to brighten, reaching a rate of 0.019 +/- 0.002 ct/s/cm^2 (~85 mCrab) on 2014 March 17. This is the first outburst from this source yet observed in the BAT monitor or by Swift, and as far as we can determine, the first outburst since discovery by SIGMA/Granat in March 1996 (Vargas et al., 1997, MNRAS 476, L23).