TITLE: GCN CIRCULAR NUMBER: 17895 SUBJECT: GRB 150530B detected in ground analysis of BAT data DATE: 15/06/02 03:16:46 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. R. Cummings (CPI) and D. M. Palmer (LANL) report on behalf of the Swift science team: At 13:28:38 during a preplanned Swift slew, GRB 150530B caused a rate increase in Swift-BAT. Photon event data were collected during the slew. In ground analysis, we detect a significant source in a mosaic image. The source was at RA, Dec 7.496, +44.290 which is: RA (J2000) 00h 29m 59.0s Dec (J2000) +44d 17' 25" with an estimated 90% containment radius of 3 arcmin. In BAT, the burst lasted 2.0 +- 0.4 seconds. The spectrum was soft, with no detected excess above 100 keV. The best fit to the spectrum from 15-150 keV is a simple power law with a photon index of 1.7 +- 0.2. The fluence in 2 seconds was (1.25 +- 0.2) x 10^-7 ergs/cm^2. The uncertainties quoted are estimated 90% confidence.