//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22155 SUBJECT: GRB 171124A: Swift ToO observations DATE: 17/11/24 11:51:18 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Fermi/LAT GRB 171124A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020784 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/LAT event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22156 SUBJECT: GRB 171124A: Fermi-LAT detection DATE: 17/11/24 11:56:09 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP F. Longo (University and INFN, Trieste), M. Arimoto (Waseda University), E. Bissaldi (Politecnico and INFN Bari) and M. Palatiello (University and INFN, Trieste) report on behalf of the Fermi-LAT collaboration: At 05:37:56.50 UT on November 24, 2017, Fermi-LAT detected high-energy emission from GRB 171124A, which was also detected by Fermi-GBM (trigger 533194681 / 171124235). The best LAT on-ground location is found to be RA, Dec = 335.52, 35.22 deg (J2000) with an error radius of 0.18 deg (90 % containment, statistical error only). This was 19 deg from the LAT boresight at the time of the trigger. More than 10 photons with Energy > 100 MeV are associated to the GRB in 350 s. The highest-energy photon is a 3.5 GeV event, which is observed 4 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Francesco Longo (francesco.longo@ts.infn.it). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22159 SUBJECT: GRB 171124A: MITSuME Akeno optical upper limits DATE: 17/11/24 14:58:20 GMT FROM: Katsuhiro L. Murata at Nagoya U K. Shiraishi, R. Itoh, K. L. Murata, T. Yoshii, Y. Tachibana, S. Harita, K. Morita, T. Ozawa, H. Mamiya, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 171124A (F. Longo et al., GCN Circular #22156) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2017-11-24 11:02:40.53 UT. We did not find any new point source within enhanced LAT circle in all three bands. We obtained following limits for the magnitudes. T0+[hour] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------ ------------------------------------------- ~6.38 12:00:00 300 >19.0 >18.5 >17.4 ------------------------------------------------------------ ------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used UCAC-4 catalog for flux calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22164 SUBJECT: GRB 171124A: Fermi GBM observation DATE: 17/11/24 16:35:48 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP E. Bissaldi (Politecnico & INFN Bari) and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 05:37:56.50 UT on 24 November 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 171124A (trigger 533194681 / 171124235), which was also detected by Fermi LAT (Longo et al. 2017, GCN 22156). The GBM on-ground location is consistent with the LAT position. The angle from the Fermi LAT boresight at the GBM trigger time is 19 degrees. The GBM light curve consists of two emission episodes with a duration (T90) of about 26 s (50-300 keV). The time-averaged spectrum from T0-1.3 s to T0+22 s is well fit by a Band function with Epeak = 1.12 +/- 0.28 MeV, alpha = -1.01 +/- 0.05, and beta = -2.10 +/- 0.22. The event fluence (10-1000 keV) in this time interval is (1.1 +/- 0.3)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+7.3 s in the 10-1000 keV band is 4.5 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22165 SUBJECT: GRB 171124A: Swift-XRT observations DATE: 17/11/24 17:36:28 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 171124A (Longo et al. GCN Circ. 22156), collecting 4.6 ks of Photon Counting (PC) mode data between T0+21.8 ks and T0+33.1 ks. Four uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 1: RA (J2000.0): 335.42198 = 22:21:41.28 Dec (J2000.0): +35.14890 = +35:08:56.0 Error: 2.8 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (7.5 +/- 1.5)e-3 ct s^-1 Distance: 385 arcsec from Fermi/LAT position. Flux: (1.85 +/- 0.38)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 335.47618 = 22:21:54.28 Dec (J2000.0): +35.33200 = +35:19:55.2 Error: 2.3 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0243 +/- 0.0029 ct s^-1 Distance: 423 arcsec from Fermi/LAT position. Flux: (7.33 +/- 0.86)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 3: RA (J2000.0): 335.3767 = 22:21:30.42 Dec (J2000.0): +35.1638 = +35:09:49.7 Error: 4.6 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (3.52 [+1.20, -0.99])e-3 ct s^-1 Distance: 467 arcsec from Fermi/LAT position. Flux: (1.10 [+0.38, -0.31])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 335.49592 = 22:21:59.02 Dec (J2000.0): +35.16340 = +35:09:48.2 Error: 2.8 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (5.6 +/- 1.3)e-3 ct s^-1 Distance: 215 arcsec from Fermi/LAT position. Flux: (2.04 +/- 0.49)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020784. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22168 SUBJECT: GRB 171124A: AstroSat CZTI detection DATE: 17/11/24 21:17:53 GMT FROM: Vidushi Sharma at IUCAA V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration: Analysis of Astrosat CZTI data showed the detection of a GRB 171124A, which was also detected by Fermi-LAT (Longo F. et al., GCN 22156) and Fermi-GBM (Bissaldi E. et al., GCN 22164). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 05:38:00.500 UT, ~4 s after the Fermi trigger. The measured peak count rate is 161.3 cts/s above the background in combined data of four quadrants, with a total of 1157 cts. The local mean background count rate was 424.7 cts/s. Using cumulative rates, we measure a T90 of 8.4 s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22171 SUBJECT: GRB 171124A: Insight-HXMT/HE detection DATE: 17/11/27 14:06:03 GMT FROM: Li Xufang at IHEP X.F. Li, S. L. Xiong, X. B. Li, C. K. Li, C. Z. Liu, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: During the commissioning phase, at 2017-11-24T05:38:03.000 (T0), Insight-HXMT/HE detected GRB 171124A (trigger ID: HEB171124234) in a routine search of the data, which was also observed by Fermi-LAT (F. Longo et al, GCN Circ.22156), Fermi/GBM(E. Bissaldi et al, GCN Circ.22164)，AstroSat CZTI（V. Sharma et al，GCN Circ.22168）. The Insight-HXMT light curve mainly consists of two emission episodes with a duration (T90) of 17.27 s measured from T0-5.66 s. The 1-s peak rate, measured from T0-0.007 s, is 924.7 cnts/sec. The total counts from this burst is 3968.2 counts. URL_LC: http://www.hxmt.org/images/GRB/HEB171124234_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 (record 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. The analysis results presented above are preliminary; final results will be published elsewhere. 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/index.php/enhome . //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22174 SUBJECT: GRB 171124A: Swift-XRT afterglow detection DATE: 17/12/01 11:21:08 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the Fermi/LAT-detected burst GRB 171124A (Longo et al. GCN Circ. 22156). The observations now extend from T0+21.8 ks to T0+579.1 ks. Of the sources reported by Osborne et al. (GCN Circ. 22165), "Source 2" is fading with 3-sigma significance, and is therefore likely the GRB afterglow. Using 4982 s of PC mode data and 3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 335.47598, +35.33213 which is equivalent to: RA (J2000): 22h 21m 54.24s Dec(J2000): +35d 19' 55.7" with an uncertainty of 2.3 arcsec (radius, 90% confidence). This position is 7.1 arcmin from the Fermi/LAT position. The source is fading with alpha >0.7. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.8 (+0.8, -0.7). The best-fitting absorption column is 7.9 (+4.7, -3.5) x 10^21 cm^-2, in excess of the Galactic value of 1.3 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.9 x 10^-11 (1.0 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 7.9 (+4.7, -3.5) x 10^21 cm^-2 Galactic foreground: 1.3 x 10^21 cm^-2 Excess significance: 3.1 sigma Photon index: 2.8 (+0.8, -0.7) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020784. The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00020784. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22175 SUBJECT: GRB 171124A: TShAO optical observations DATE: 17/12/01 12:48:25 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kusakin (FAPHI), I. Reva (FAPHI), A. Volnova (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Fermi/LAT-detected burst GRB 171124A (Longo et al. GCN 22156) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on Nov. 27 (UT) 12:28:32. We took several images in R-filter with exposures of 120 s. We cover all LAT- localization region. The three XRT sources ## 1,3,4 (Osborne et al. GCN 22165) are detected in our stacked image. These sources are also presented in the USNO-B1.0 catalogue. We do not detect any optical object within X-ray afterglow (XRT #2 error circle, Osborne et al. GCN 22174). We may note that 4.5 arcsec South of XRT #2 we detect a galaxy which is also present in USNO-B1.0. Preliminary photometry of the field is following: Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) (3 sigma) 2017-11-27 12:28:32 3.31825 R 40*120 n/d n/d 22.0 The finding chart of the 32 XRT source can be found at http://grb.rssi.ru/GRB171124A/GRB171124A_XRT2.png The photometry is based on nearby USNO-B1.0 stars USNO-B.1_id R2 1251-0500105 14.64 1252-0499091 16.06 1251-0500220 15.86 1251-0500271 16.17 1251-0500270 16.12 1251-0500372 16.06 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22210 SUBJECT: GRB 171124A CALET Gamma-Ray Burst Monitor detection DATE: 17/12/08 00:29:41 GMT FROM: Takanori Sakamoto at AGU A. Tezuka, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada, S. Matsukawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long-duration GRB 171124A (Longo et al., GCN circ. 22156; Bissaldi et al., GCN circ. 22164; Sharma et al., GCN circ. 22168; Li et al., GCN circ. 22171) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 05:37:55.34 on 24 November 2017. The burst signal was only seen by the SGM instrument. The light curve of the SGM shows several peaks. The emission starts at T0, peaks at T+9 sec and ends at T+21 sec. The T90 duration measured by the SGM data is 17.8 +- 0.5 sec (40-1000 keV). The light curve is available at http://cgbm.calet.jp/cgbm_trigger/flight/1195536953/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.