//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26612 SUBJECT: IPN triangulation of GRB 191227B (short) DATE: 19/12/30 12:40:46 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team, S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The very bright, short-duration GRB 191227B was detected by Fermi (GBM trigger 599160109), Mars-Odyssey (HEND), Konus-Wind, and Swift (BAT) at about 62504 s UT (17:21:44). The burst was outside the coded field of view of the BAT. We have triangulated it to two preliminary, 3 sigma error boxes whose coordinates are: Box 1: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 256.466 (17h 05m 52s) -26.739 (-26d 44' 19") Corners: 256.590 (17h 06m 22s) -26.856 (-26d 51' 20") 256.273 (17h 05m 05s) -27.785 (-27d 47' 06") 256.342 (17h 05m 22s) -26.619 (-26d 37' 09") 256.724 (17h 06m 54s) -25.195 (-25d 11' 40") --------------------------------------------- Box 2: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 257.405 (17h 09m 37s) -19.765 (-19d 45' 52") Corners: 257.550 (17h 10m 12s) -19.678 (-19d 40' 41") 257.500 (17h 10m 00s) -18.708 (-18d 42' 29") 257.260 (17h 09m 02s) -19.853 (-19d 51' 12") 257.244 (17h 08m 59s) -21.319 (-21d 19' 08") --------------------------------------------- The area of each error box is 1162 sq. arcmin, and their maximum dimension is 2.62 deg (the minimum one is 14.16 arcmin). The Sun distance for each box was ~18 deg. These error boxes are both consistent with the GBM localization. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB191227_T62500/IPN The time history and spectrum will be given in forthcoming GCN Circulars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26613 SUBJECT: Konus-Wind observation of GRB 191227B DATE: 19/12/30 12:56:09 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 191227B (IPN triangulation: Hurley et al., GCN Circ. 26612) triggered Konus-Wind at T0=62500.487 s UT (17:21:40.487). The burst light curve shows a multi-peaked structure which starts at ~T0 s and has a total duration of ~0.2 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB191227_T62500/ As observed by Konus-Wind, the burst had a fluence of 8.80(-1.42,+1.40)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.030 s, of 8.83(-2.12,+2.10)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.192 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.56(-0.21,+0.31), the high energy photon index beta = -2.35(-1.19,+0.38), the peak energy Ep = 985(-323,+373) keV (chi2 = 49/49 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26617 SUBJECT: GRB 191227B: Insight-HXMT/HE observation DATE: 19/12/31 03:43:14 GMT FROM: Yunfei Du at IHEP Y. F. Du, Y. G. Zheng, C. Cai, Q. Luo, S. Xiao, Q. B. Yi, Y. Huang, C. K. Li, G. Li, X. B. 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 2019-12-27T17:21:44.14 (T0), Insight-HXMT/HE detected GRB 191227B (trigger ID: HEB191227723) in a routine search of the data, which was also triggered by Fermi/GBM, IPN and Konus-Wind (GCN #26612). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a duration (T90) of 0.161 s measured from T0+0.010 s. The 1-ms peak rate, measured from T0+0.045 s, is 50,544 cnts/sec. The total counts from this burst is 4123 counts. But it should be noted that the Insight-HXMT/HE detection suffers from saturation when the count rate exceeds ~20,000 cnts/sec. The uncorrected light curve can be found at: URL_LC: http://www.hxmt.org/images/GRB/HEB191227723_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.