//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26081 SUBJECT: GRB 191025B: Insight-HXMT/HE detection DATE: 19/10/28 03:31:23 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 2019-10-25T18:42:09.10 (T0), Insight-HXMT/HE detected GRB 191025A (trigger ID: HEB191025779) in a routine search of the data, which was also triggered by INTEGRAL/SPIACS (Trigger Number: 8394) and Konus-Wind. The Insight-HXMT/HE light curve mainly consists of multiple pulses with a duration (T90) of 0.145 s measured from T0+0.03 s. The 1-ms peak rate, measured from T0+0.123 s, is 63021 cnts/sec. The total counts from this burst is 2544 counts. The data of Insight-HXMT/HE suffers saturation in the brightest part. URL_LC: http://www.hxmt.org/images/GRB/HEB191025779_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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26086 SUBJECT: IPN triangulation of GRB 191025B (short) DATE: 19/10/28 20:30:41 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, K. Hurley, on behalf of the IPN, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and Q. Luo, X. B. Li, Y. Huang, S. L. Xiong, and S. N. Zhang, on behalf of the Insight-HXMT team, report: The short-duration, very bright GRB 191025B (Insight-HXMT detection: Luo et al., GCN Circ. 26081) was detected by Konus-Wind, INTEGRAL (SPI-ACS), and Insight-HXMT, at about 67329 s UT (18:42:09). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 60.104 (04h 00m 25s) +56.480 (+56d 28' 47") Corners: 61.751 (04h 07m 00s) +54.782 (+54d 46' 54") 60.165 (04h 00m 40s) +56.600 (+56d 36' 01") 58.207 (03h 52m 50s) +58.177 (+58d 10' 36") 60.041 (04h 00m 10s) +56.360 (+56d 21' 36") --------------------------------------------- The error box area is 1261 sq. arcmin, and its maximum dimension is 3.9 deg (the minimum one is 10.3 arcmin). The Sun distance was about 130 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB191025_T67331/IPN/ The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26089 SUBJECT: Konus-Wind observation of GRB 191025B DATE: 19/10/29 12:34:07 GMT FROM: Anna Kozlova at Ioffe Institute A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 191025B (Insight-HXMT detection: Luo et al., GCN Circ. 26081; IPN triangulation: Svinkin et al., GCN Circ. 26086) triggered Konus-Wind at T0=67331.034 s UT (18:42:11.034). The burst light curve shows a single pulse started at ~T0 with a total duration of ~0.2 s. The emission is seen up to ~10 MeV. As observed by Konus-Wind, the burst had a fluence of 8.41(-1.44,+1.52)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-0.006 s, of 1.32(-0.32,+0.33)x10^-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+0.128 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.84(-0.11,+0.13) and Ep = 2184(-608,+812) keV (chi2 = 23/26 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.9 (chi2 =22/25 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB191025_T67331/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26106 SUBJECT: GRB 191025B: AstroSat CZTI detection DATE: 19/10/31 18:19:38 GMT FROM: Ramkrishna Gaikwad at IUCAA/AstroSat R. Gaikwad, S. Gupta, 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 191025B, which was also detected by Insight-HXMT/HE (Luo Q. et al., GCN #26081), IPN triangulation (Svinkin D. et al., GCN #26086) and Konus-Wind (Kozlova et al., GCN #26089). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple pulses of emission with the strongest peak at 2019-10-25 18:42:09.0 UT. The measured peak count rate associated with the burst is 449 cts/s above the background in the combined data of four quadrants, with a total of 567 cts. The local mean background count rate was 514 cts/s. Using cumulative rates, we measure a T90 of 6.9 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.