//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22607 SUBJECT: GRB 180404C CALET Gamma-Ray Burst Monitor detection DATE: 18/04/06 01:23:16 GMT FROM: Takanori Sakamoto at AGU P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo, A. Tezuka, 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, and the CALET collaboration: The long-duration, hard-spectrum, bright GRB 180404C triggered the CALET Gamma-ray Burst Monitor (CGBM) at 21:42:08.587 UTC on 4 April 2018. The burst signal was seen by all CGBM detectors. This GRB is also clearly seen by the publicly available INTEGRAL SPI-ACS light curve. The burst light curve shows a single pulse which starts at T+1.7 sec, peaks at T+5.5 sec and ends at T+34.1 sec. The T90 and the T50 durations measured by the SGM data are 25.4 +- 3.1 sec and 9.5 +- 1.4 sec (40-1000 keV), respectively. CGBM HV was turned off at ~T+65 sec due to entering the radiation belts, so no CGBM data are available from that time until ~T+1000 sec. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1206913306/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22610 SUBJECT: IPN Triangulation of GRB 180404C (long) DATE: 18/04/06 18:02:49 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, A. Ursi, N. Parmiggiani, F. Verrecchia, A. Bulgarelli, A. Trois, M. Marisaldi, C. Pittori, M. Tavani, Y. Evangelista, I. Donnarumma, M. Cardillo, G. Piano, G. Minervini, A. Argan, F. Lucarelli, A. Zoli, V. Fioretti, F. Fuschino, M. Pilia, F. Longo, A. Giuliani on behalf of the AGILE team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 180404C (Marrocchesi et al., GCN Circ. 22607) was detected by Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), CALET (CGBM), and AGILE (MCAL) at about 78128 s UT (21:42:08). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 92.302 (06h 09m 13s) +7.811 ( +7d 48' 38") Corners: 94.505 (06h 18m 01s) +6.262 ( +6d 15' 44") 90.162 (06h 00m 39s) +8.179 ( +8d 10' 43") 90.059 (06h 00m 14s) +9.822 ( +9d 49' 21") 94.425 (06h 17m 42s) +7.688 ( +7d 41' 17") --------------------------------------------- The error box area is 6.37 sq. deg, and its maximum dimension is 5.66 deg (the minimum one is 80 arcmin). The Sun distance was 75 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180404_T78131/IPN The Konus-Wind time history and spectrum will be given a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22624 SUBJECT: Konus-Wind observation of GRB 180404C DATE: 18/04/10 14:05:04 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 180404C (CATET-GBM detection: Marrocchesi et al., GCN Circ. 22607; IPN triangulation: Hurley et al., GCN Circ. 22610) triggered Konus-Wind at T0=78131.929 s UT (21:42:11.929). The burst light curve shows a multi-peaked structure which starts at ~T0-88 s and has a total duration of ~200 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/GRB180404_T78131/ As observed by Konus-Wind, the burst had a fluence of 1.33(-0.18,+0.19)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+2.672 s, of 2.11(-0.37,+0.37)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+116.736 s) is best fit in the 20 keV - 19 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.00(-0.10,+0.12), the high energy photon index beta = -2.40(-0.56,+0.24), the peak energy Ep = 342(-49,+58) keV (chi2 = 91/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+4.864 s) is best fit in the 20 keV - 19 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.58(-0.11,+0.13), the high energy photon index beta = -2.00(-0.12,+0.09), the peak energy Ep = 517(-71,+86) keV (chi2 = 86/94 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.