//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28958 SUBJECT: GRB 201128A: Swift detection of a burst DATE: 20/11/28 06:44:21 GMT FROM: David Palmer at LANL A. Y. Lien (GSFC/UMBC), E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST), K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Neil Gehrels Swift Observatory Team: At 06:27:58 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201128A (trigger=1009679). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 223.136, +26.678 which is RA(J2000) = 14h 52m 33s Dec(J2000) = +26d 40' 41" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 10 sec. The peak count rate was ~600 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 06:30:04.8 UT, 126.6 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 223.1083, 26.6844 which is equivalent to: RA(J2000) = 14h 52m 26.00s Dec(J2000) = +26d 41' 03.8" with an uncertainty of 2.6 arcseconds (radius, 90% containment). This location is 92 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 3.53 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 130 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28959 SUBJECT: GRB 201128A: DDOTI Observations DATE: 20/11/28 15:11:50 GMT FROM: Alan M Watson at UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara (GSFC/UMD), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl Lopez (UNAM), Diego Gonzalez (UNAM), Margarita Pereyra (UNAM), Srihari Ravi (ASU), and Eleonora Troja (GSFC/UMD) report: We observed the field of GRB 201128A (Lien et al., GCN Circ. 28958) with with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2020-11-28 UTC. We observed from 2020-11-30 12:45 to 13:07 (from 6.3 to 6.7 hours after the trigger) obtaining a total of 960 seconds exposure in the w filter. We calibrate our images against the APASS catalog. Our 5-sigma limiting magnitude is w = 20.4. Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogs, we detect no uncatalogued sources in the Swift/XRT error region (Lien et al., GCN Circ. 28958 to our 5-sigma limit. We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28960 SUBJECT: GRB 201128A: Enhanced Swift-XRT position DATE: 20/11/28 15:58:08 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 1017 s of XRT Photon Counting mode data and 2 UVOT images for GRB 201128A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 223.10767, +26.68502 which is equivalent to: RA (J2000): 14h 52m 25.84s Dec (J2000): +26d 41' 06.1" with an uncertainty of 2.0 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28962 SUBJECT: GRB 201128A: Swift-XRT refined Analysis DATE: 20/11/28 22:44:04 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC), V. D'Elia (ASDC), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and A.Y. Lien report on behalf of the Swift-XRT team: We have analysed 9.4 ks of XRT data for GRB 201128A (Lien et al. GCN Circ. 28958), from 133 s to 46.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 28960). The light curve can be modelled with a power-law decay with a decay index of alpha=0.58 (+/-0.04). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.09 (+0.23, -0.21). The best-fitting absorption column is 1.6 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 3.5 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.6 (+0.7, -0.6) x 10^21 cm^-2 Galactic foreground: 3.5 x 10^20 cm^-2 Excess significance: 3.4 sigma Photon index: 2.09 (+0.23, -0.21) If the light curve continues to decay with a power-law decay index of 0.58, the count rate at T+24 hours will be 0.014 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.6 x 10^-13 (5.5 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01009679. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28963 SUBJECT: GRB 201128A: Swift-BAT refined analysis DATE: 20/11/29 03:42:15 GMT FROM: Sibasish Laha at GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 201128A (trigger #1009679) (Lien et al., GCN Circ. 28958). The BAT ground-calculated position is RA, Dec = 223.091, 26.716 deg which is RA(J2000) = 14h 52m 21.9s Dec(J2000) = +26d 42' 58.6" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%. The BAT light curve showed a complex structure with a duration of about 30 sec. T90 (15-350 keV) is 5.41 +- 3.22 sec (estimated error including systematics). The time-averaged spectrum from T-0.44 to T+8.74 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.37 +- 0.37. The fluence in the 15-150 keV band is 2.0 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+4.21 sec in the 15-150 keV band is 0.4 +- 0.2 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/1009679/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28970 SUBJECT: GRB 201128A: Swift/UVOT Upper Limits DATE: 20/11/30 23:24:56 GMT FROM: Alexander Belles at PSU/Swift GRB 201128A: Swift/UVOT Upper Limits A. Belles (PSU) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 201128A 130 s after the BAT trigger (Lien et al., GCN Circ. 28958). No optical afterglow consistent with the XRT position (Lien et al. GCN Circ. 28958) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 130 280 147 >20.0 u_FC 289 538 246 >19.3 white 130 761 186 >20.0 v 619 639 19 >17.4 b 544 737 39 >18.6 u 289 538 246 >19.3 w1 668 688 19 >18.3 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).