TITLE: GCN CIRCULAR NUMBER: 28845 SUBJECT: GRB 201105A: Swift detected burst and BAT refined analysis DATE: 20/11/06 01:13:41 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), N. J. Klingler (PSU), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), K. K. Simpson (PSU), M. Stamatikos (OSU),T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): At 2020-11-05 05:31:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201105A (trigger=1004239). The burst occurred during GCN downtime, and the initial circular (Simpson et al.) may have been lost. We thus include information from that circular here as well. The GRB location is Sun-constrained until 2020-12-27, so no XRT or UVOT data are available. Using the data set from T-239 to T+963 sec from the recent telemetry downlink, the BAT ground-calculated position is RA, Dec = 245.610, 12.734 deg which is RA(J2000) = 16h 22m 26.4s Dec(J2000) = +12d 44' 03.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60% The BAT mask-weighted light curve shows a FRED-like pulse that starts at ~T-3 s and peaks at ~T+1 s. The main structure ends at ~T+40 s, with a tail emission that lasts till ~T+100 s. T90 (15-350 keV) is 33.82 +- 4.03 sec (estimated error including systematics). The time-averaged BAT spectrum from T-2.85 to T+72.11 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.08 +- 0.03. The fluence in the 15-150 keV band is 1.2 +- 0.02 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+0.76 sec in the 15-150 keV band is 13.9 +- 0.5 ph/cm2/sec. 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/1004239/BA/ Burst Advocate for this burst is K. K. Simpson (kira.simpson1984 AT gmail.com). 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/)