//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26107 SUBJECT: GRB 191031C: Fermi GBM Final Real-time Localization DATE: 19/10/31 18:53:33 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 18:43:16 UT on 31 Oct 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 191031C (trigger 594240201.70685 / 191031780). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 120.8, Dec = -59.6 (J2000 degrees, equivalent to J2000 08h 03m, -59d 36'), with a statistical uncertainty of 1.6 degrees. The angle from the Fermi LAT boresight is 19.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn191031780/quicklook/glg_skymap_all_bn191031780.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn191031780/quicklook/glg_healpix_all_bn191031780.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn191031780/quicklook/glg_lc_medres34_bn191031780.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26108 SUBJECT: GRB 191031C: Swift detection of a burst DATE: 19/10/31 18:55:34 GMT FROM: David Palmer at LANL E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), J.D. Gropp (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF), S Laha (GSFC/UMBC/CRESST), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 18:43:54 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 191031C (trigger=932595). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 115.862, -62.335 which is RA(J2000) = 07h 43m 27s Dec(J2000) = -62d 20' 04" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 80 sec. The peak count rate was ~2400 counts/sec (15-350 keV), at ~4 sec after the trigger. The XRT began observing the field at 18:45:16.2 UT, 81.3 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 115.8682, -62.3247 which is equivalent to: RA(J2000) = 07h 43m 28.37s Dec(J2000) = -62d 19' 28.9" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 38 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 2.60e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 90 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 19.6 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 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.17. Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26109 SUBJECT: GRB 191031C: Prompt enhanced Swift-XRT position DATE: 19/10/31 19:20:12 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using promptly downlinked XRT event data for GRB 191031C, we find an enhanced XRT position of the afterglow: RA, Dec: 115.8709, -62.3251 which is equivalent to: RA (J2000) = 07 43 29.01 Dec (J2000) = -62 19 30.5 with an uncertainty of 2.0 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/932595. Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26111 SUBJECT: GRB 191031C: Fermi GBM Final Real-time Localization DATE: 19/10/31 21:33:56 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely SHORT GRB At 21:23:31 UT on 31 Oct 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 191031C (trigger 594249816.128134 / 191031891). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 282.8, Dec = 55.0 (J2000 degrees, equivalent to J2000 18h 51m, 55d 00'), with a statistical uncertainty of 2.4 degrees. The angle from the Fermi LAT boresight is 58.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn191031891/quicklook/glg_skymap_all_bn191031891.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn191031891/quicklook/glg_healpix_all_bn191031891.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn191031891/quicklook/glg_lc_medres34_bn191031891.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26115 SUBJECT: GRB 191031C: Enhanced Swift-XRT position DATE: 19/10/31 22:53:20 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 1562 s of XRT Photon Counting mode data and 3 UVOT images for GRB 191031C, 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 = 115.87049, -62.32466 which is equivalent to: RA (J2000): 07h 43m 28.92s Dec (J2000): -62d 19' 28.8" with an uncertainty of 1.8 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: 26119 SUBJECT: GRB 191031C: Fermi GBM detection DATE: 19/11/01 03:48:32 GMT FROM: Cori Fletcher at USRA C. Fletcher (USRA), R. Hamburg (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 18:43:16.71 UT on 31 October 2019, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 191031C (trigger 594240201 / 191031780) which was also detected by the Swift BAT and XRT (Ambrosi et al. 2019, GCN 26108). The Fermi GBM Final Real-time Localization (GCN 26107) is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 20 degrees. The GBM light curve shows a complex, multi-peaked structure with a duration (T90) of about 78 s (50-300 keV). The time-averaged spectrum from T0+3.3 s to T0+81.2 s is best fit by a Band function with Epeak = 107 +/- 9 keV, alpha = -0.5 +/- 0.1, and beta = -2.3 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (1.33 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+42.2 s in the 10-1000 keV band is 7.3 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26127 SUBJECT: GRB 191031C: Swift/UVOT Detection DATE: 19/11/01 16:22:13 GMT FROM: Sam LaPorte at PSU GRB 191031C: Swift/UVOT Detection J. D. Gropp (PSU) and Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 191031C 91 s after the BAT trigger (Ambrosi et al., GCN Circ. 26108). A source consistent with the XRT position (Goad et al. GCN Circ. 26115) is detected in the initial UVOT exposures. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u 307 556 245 >19.71 white 92 242 147 20.27+-0.32 white 862 1011 147 >20.39 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.17 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26130 SUBJECT: GRB 191031C: Swift-XRT refined Analysis DATE: 19/11/01 18:56:03 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), J. D. Gropp (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC), A. Tohuvavohu (U. Toronto) and E. Ambrosi report on behalf of the Swift-XRT team: We have analysed 4.9 ks of XRT data for GRB 191031C (Ambrosi et al. GCN Circ. 26108), from 87 s to 52.5 ks after the BAT trigger. The data comprise 1.6 ks in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 26109). The late-time light curve (from T0+6.6 ks) can be modelled with a power-law decay with a decay index of alpha=1.06 (+0.17, -0.13). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.99 (+0.08, -0.06). The best-fitting absorption column is 1.87 (+0.28, -0.08) x 10^21 cm^-2, consistent with the Galactic value of 1.8 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.79 (+0.12, -0.05) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (4.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.8 (+0.4, -0.0) x 10^21 cm^-2 Galactic foreground: 1.8 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.79 (+0.12, -0.05) If the light curve continues to decay with a power-law decay index of 1.06, the count rate at T+24 hours will be 0.029 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-12 (1.4 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00932595. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26132 SUBJECT: GRB 191031C: Swift-BAT refined analysis DATE: 19/11/01 19:06:54 GMT FROM: Hans Krimm at NSF/NASA-GSFC D. M. Palmer (LANL), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), 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-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 191031C (trigger #932595) (Ambrosi, et al., GCN Circ. 26108). The BAT ground-calculated position is RA, Dec = 115.880, -62.322 deg which is RA(J2000) = 07h 43m 31.2s Dec(J2000) = -62d 19' 20.1" with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 24%. The mask-weighted light curve shows several peaks. The first begins around T-40 sec and runs until T-20 sec. The second, brightest, peak begins immediately after, peaks around T+5 sec, and decays to background by T+120 sec. There are several weak peaks superimposed on this one, the largest coming around T+45 sec. T90 (15-350 keV) is 93.2 +- 19.0 sec (estimated error including systematics). The time-averaged spectrum from T-37.98 to T+112.66 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.07. The fluence in the 15-150 keV band is 7.2 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+4.04 sec in the 15-150 keV band is 4.6 +- 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/932595/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26146 SUBJECT: GRB 191031C: Insight-HXMT/HE detection DATE: 19/11/02 15:20:49 GMT FROM: Qi Luo at IHEP Q. Luo, C. Cai, S. Xiao, Q. B. Yi, Y. G. Zheng, Y. Huang, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: At 2019-10-31T18:43:16.00 (T0), Insight-HXMT/HE detected GRB 191031C (trigger ID: HEB191031780) in a routine search of the data, which was also triggered by Fermi/GBM (GCN #26107) and Swift-BAT (GCN #26108). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a duration (T90) of 47.315 s measured from T0+0.74 s. The 1-ms peak rate, measured from T0+42.703 s, is 848 cnts/sec. The total counts from this burst is 11529 counts. The data of Insight-HXMT/HE suffers saturation in the brightest part. URL_LC: http://www.hxmt.org/images/GRB/HEB191031780_lc.jpg All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.