//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27726 SUBJECT: GRB 200512A: Swift detection of a burst DATE: 20/05/12 20:53:23 GMT FROM: David Palmer at LANL K. K. Simpson (PSU), V. D'Elia (SSDC), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: At 20:33:15 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200512A (trigger=971846). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 7.396, -2.199 which is RA(J2000) = 00h 29m 35s Dec(J2000) = -02d 11' 54" 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 20 sec. The peak count rate was ~600 counts/sec (15-350 keV), at ~3 sec after the trigger. The XRT began observing the field at 20:34:25.5 UT, 69.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 7.41520, -2.21052 which is equivalent to: RA(J2000) = 00h 29m 39.65s Dec(J2000) = -02d 12' 37.9" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 80 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 2.94 x 10^20 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 7.60e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 235 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27728 SUBJECT: GRB 200512A: Enhanced Swift-XRT position DATE: 20/05/13 04:28:29 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 744 s of XRT Photon Counting mode data and 1 UVOT images for GRB 200512A, 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 = 7.41477, -2.21036 which is equivalent to: RA (J2000): 00h 29m 39.54s Dec (J2000): -02d 12' 37.3" with an uncertainty of 1.4 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: 27729 SUBJECT: GRB 200512A: Swift-XRT refined Analysis DATE: 20/05/13 15:39:48 GMT FROM: Phil Evans at U of Leicester A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and K.K. Simpson report on behalf of the Swift-XRT team: We have analysed 7.4 ks of XRT data for GRB 200512A (Simpson et al. GCN Circ. 27726), from 63 s to 58.1 ks after the BAT trigger. The data comprise 153 s in Windowed Timing (WT) mode (the first 5 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 27728). The light curve can be modelled with an initial power-law decay with an index of alpha=0.42 (+0.20, -0.37), followed by a break at T+161 s to an alpha of 1.93 (+/-0.10). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.49 (+/-0.13). The best-fitting absorption column is 2.6 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 2.9 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.20 (+0.23, -0.22) and a best-fitting absorption column of 2.4 (+1.4, -1.2) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.1 x 10^-11 (6.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.4 (+1.4, -1.2) x 10^21 cm^-2 Galactic foreground: 2.9 x 10^20 cm^-2 Excess significance: 3.0 sigma Photon index: 1.20 (+0.23, -0.22) If the light curve continues to decay with a power-law decay index of 1.93, the count rate at T+24 hours will be 6.7 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.1 x 10^-15 (4.5 x 10^-15) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00971846. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27730 SUBJECT: GRB 200512A: Swift/UVOT Upper Limits DATE: 20/05/13 16:56:49 GMT FROM: Frank Marshall at Swift/UVOT F. E. Marshall (NASA/GSFC) and K. K. Simpson (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 200512A 78 s after the BAT trigger (Simpson et al., GCN Circ. 27726). No optical afterglow consistent with the enhanced XRT position (Goad et al., GCN Circ. 27728) 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) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 78 228 147 >19.9 u_FC 236 486 246 >19.8 v 567 760 39 >17.1 b 493 858 58 >19.0 u 236 833 285 >19.7 w1 617 809 39 >17.9 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). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27731 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 200512A DATE: 20/05/13 20:19:43 GMT FROM: Peter Veres at UAH P. Veres (UAH) reports on behalf of the Fermi-GBM Team: Swift-BAT detected GRB 200512A at 20:33:15 UT (GCN 27726). There was no Fermi-GBM onboard trigger around the event. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no counterparts. The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around BAT trigger time. A transient source was identified whose most significant timescale according to the search is 8.192 s, with a log likelihood ratio of 23. It has consistent location, and it is consistent with a "normal" spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB. [1] Goldstein et al. 2019 arXiv:1903.12597 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27733 SUBJECT: GRB 200512A: LCO Optical Upper Limits DATE: 20/05/13 20:46:43 GMT FROM: Robert Strausbaugh at U. of the Virgin Islands R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration: We observed Swift GRB 200512A (Simpson et al., GCN 27726) with the LCO 1-m Sinistro instrument at the Siding Spring Observatory, Australia site, on May 13, from 19:03 to 19:25 UT (corresponding to 23.50 to 23.87 hours from the GRB trigger time) with the Bessel I and R filters. We performed a series of 5x120s exposures in R and I. We do not detect any fading sources in the individual frames (or in stacked images). Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits: R > 20.90 I > 20.29 These magnitudes are not corrected for galactic extinction. R.S. is funded by NSF AST grant #1831682 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27742 SUBJECT: GRB 200512A: Swift-BAT refined analysis DATE: 20/05/14 23:33:47 GMT FROM: Amy Lien at GSFC T. Sakamoto (AGU), 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), D. M. Palmer (LANL), K. K. Simpson (PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200512A (trigger #971846) (Simpson et al., GCN Circ. 27726). The BAT ground-calculated position is RA, Dec = 7.417, -2.217 deg which is RA(J2000) = 00h 29m 40.2s Dec(J2000) = -02d 13' 01.1" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a single-pulse structure. The main emission starts at ~T-3 s, peaks at ~T+3 s, and ends at ~T+40 s. In addition, there are some weak emission that lasts until ~T+80 s. T90 (15-350 keV) is 74.0 +- 14.3 sec (estimated error including systematics). The time-averaged spectrum from T-2.86 to T+78.14 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.68 +- 0.18. The fluence in the 15-150 keV band is 8.1 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+3.14 sec in the 15-150 keV band is 0.4 +- 0.1 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/971846/BA/