//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18225 SUBJECT: GRB 150901A: Swift detection of a burst DATE: 15/09/01 15:40:23 GMT FROM: Scott Barthelmy at NASA/GSFC B. Sbarufatti (INAF-OAB/PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA) and T. N. Ukwatta (LANL) report on behalf of the Swift Team: At 15:26:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150901A (trigger=654042). Swift did not slew due Sun observing constraint. The BAT on-board calculated location is RA, Dec 183.586, +25.038, which is RA(J2000) = 12h 14m 21s Dec(J2000) = +25d 02' 19" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak with a duration of about 25 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~1 sec after the trigger. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 00:01 UT on 2015 October 28. There will thus be no XRT or UVOT data for this trigger before this time. Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18232 SUBJECT: GRB 150901A, Swift-BAT refined analysis DATE: 15/09/03 12:53:33 GMT FROM: Amy Lien at GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-254 to T+640 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150901A (trigger #654042) (Sbarufatti, et al., GCN Circ. 18225). The BAT ground-calculated position is RA, Dec = 183.609, 25.076 deg which is RA(J2000) = 12h 14m 26.1s Dec(J2000) = +25d 04' 35.2" with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 41%. The mask-weighted light curve shows some weak emissions that start at ~ T-70 s, followed by the main structure with several overlapping pulses from ~T0 to ~T+18 s. T90 (15-350 keV) is 64.0 +- 35.8 sec (estimated error including systematics). The time-averaged spectrum from T-61.8 to T+18.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.72 +- 0.53. The fluence in the 15-150 keV band is 4.5 +- 1.3 x 10^-7 erg/cm2. The 1-s peak photon flux is unconstrained due to the weakness of the burst. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/654042/BA/