TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3024 SUBJECT: Swift-BAT detects two bursts: GRB050215a and GRB050215b DATE: 05/02/15 04:45:33 GMT FROM: Scott Barthelmy at NASA/GSFC S. Barthelmy, L. Barbier, J. Cummings (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), J. Greiner (MPE), D. Hinshaw (GSFC-SPSYS), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), T. Mitani (ISAS), K. Nakazawa (ISAS), J. Norris (GSFC), D. Palmer (LANL), A. Parsons, T. Sakamoto (GSFC) G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC), on behalf of the Swift-BAT team: The BAT instrument on Swift triggered at 02:15:28 and at 02:33:12 UT 15 Feb 05, triggers 106106 and 106107, respectively. We have done preliminary analysis on the ground using the TDRSS messages and the initial portions of the data from a telemetry downlink. For GRB050215a (Trigger 106106) the position is RA,Dec=348.382,+49.322 (J2000) with a position uncertainty of 4 arcmin (statistical plus systematic, 90% containment radius). The lightcurve is a single peak with a duration of ~6 seconds. Nearly all of the emission is in the 15-25 keV band. The Swift spacecraft automatically slewed to this burst and began follow-up observations, but that follow-up sequence was interrupted by the second burst (18 min later). For GRB050215b (Trigger 106107) the position is RA,Dec=174.450,+40.805 (J2000) with a position uncertainty of 4 arcmin (statistical plus systematic, 90% containment radius). The lightcurve is a single peak with a duration of ~10 seconds. The emission extends from 15 to ~100 keV. The Swift spacecraft also automatically slewed to this burst location and is currently doing an extended follow-up observation on this burst. We note that this burst is well suited for ground-based optical follow-up observations in the Northern hemisphere. We note that these bursts are clearly distinct and separate from each other. It is merely coincidental that these two bursts happened within a few hours after the enabling of the automatic real-time distribution of the Notices.