//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30531 SUBJECT: GRB 210727A: BALROG localization (Fermi Trigger 649072251 / GRB 210727410) DATE: 21/07/27 11:44:42 GMT FROM: Jochen Greiner at MPE,Garching B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 649072251 at 09:50:46 on 27 July 2021 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position (1 sigma statistical errors) is: RA(2000.0) = 184.2+/-6.6 deg Decl.(2000.0) = -64.3+/-3.5 deg We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB210727410/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210727410/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210727410/json //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30533 SUBJECT: GRB 210727A: AGILE/MCAL detection DATE: 21/07/27 14:43:39 GMT FROM: Alessandro Ursi at INAF/IAPS A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team: The AGILE Mini-CALorimeter (MCAL) detected the short GRB 210727A (Fermi trigger no. 649072251) at T0 = 2021-07-27 09:50:47.40 +/- 0.01 s (UTC). The event lasted about 1.5 s and released a total number of ~1300 counts in the detector (in the 0.4-100 MeV energy range), above an average background rate of 560 Hz. The MCAL light curve can be found at http://www.agilescienceapp.it/notices/074097_GRB_MCAL_554464247.402495.png . The time-integrated spectrum of the burst can be fitted in the energy range 0.4-20 MeV with a single power-law with ph.ind. = -1.59 -/+ 0.07, resulting in a reduced chi-squared of 1.23 (62 d.o.f.) and a fluence of 9.6e-06 ergs/cm^2 (90% confidence level), in the same energy range. The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30541 SUBJECT: IPN triangulation of GRB 210727A (short) DATE: 21/07/28 18:09:24 GMT FROM: Anna Ridnaia at Ioffe Institute A. Ridnaia, S. Golenetskii, D. Frederiks, D. Svinkin, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, K. Hurley, on behalf of the IPN, A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, report: The short-duration GRB 210727A (BALROG localization: Biltzinger et al., GCN 30531; AGILE-MCAL detection: Ursi et al., GCN 30533) was detected by Fermi (GBM trigger 649072251), Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), AGILE (MCAL), and CALET (CGBM) at about 35447 s UT (09:50:47). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 189.231 (12h 36m 55s) -59.926 (-59d 55' 35") Corners: 194.539 (12h 58m 09s) -56.353 (-56d 21' 12") 193.795 (12h 55m 11s) -56.308 (-56d 18' 30") 182.624 (12h 10m 30s) -63.300 (-63d 17' 59") 183.549 (12h 14m 12s) -63.394 (-63d 23' 37") --------------------------------------------- The error box area is 3.28 sq. deg, and its maximum dimension is 9.14 deg (the minimum one is 22 arcmin). The Sun distance was 93 deg. This box may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi final position and the BALROG localization. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210727_T35447/IPN The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30544 SUBJECT: GRB 210727A: CALET Gamma-Ray Burst Monitor detection DATE: 21/07/29 10:11:54 GMT FROM: Valentin Pal'shin at AGU Y. Akaike (Waseda U), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR), S. Torii, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The short GRB 210727A (BALROG localization: Biltzinger et al., GCN Circ. 30531; AGILE/MCAL detection: Ursi et al., GCN Circ. 30533; IPN triangulation: Ridnaia et al., GCN Circ. 30541; https://gcn.gsfc.nasa.gov/other/210727A.gcn3) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 09:50:46.605 UTC on 27 July 2021. The burst signal was seen by all CGBM detectors. The burst light curve shows a multi-peaked structure which starts at T-0.38 sec and ends at T+0.64 sec. The T90 and T50 durations measured by the SGM data are 0.96 +- 0.14 sec and 0.51 +- 0.09 sec (40-1000 keV), respectively. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1311414395/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30549 SUBJECT: GRB 210727A: AstroSat CZTI detection DATE: 21/07/30 06:21:59 GMT FROM: Gaurav Waratkar at IIT,Bombay V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al, 2020, arxiv:2011.07067) showed detection of a short GRB 210727A, which was also detected by Fermi-GBM (Trigger no. 649072251), AGILE/MCAL (Ursi et al., GCN 30533), CALET (Akaike et al., GCN 30544), with IPN localization (Ridnaia et al., GCN 30541) and BALROG localization (Biltzinger et al., GCN 30531). The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2021-07-27 09:50:46.45 UT. The measured peak count rate associated with the burst is 890 (+197, -153) cts/s above the background in the combined data of four quadrants, with a total of 489 (+74, -67) cts. The local mean background count rate was 482 (+11, -15) cts/s. Using cumulative rates, we measure a T90 of 0.9 (+0.3, -0.1) s. It was also 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.