//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33492 SUBJECT: GRB 230320B: AstroSat CZTI detection DATE: 23/03/21 09:11:08 GMT FROM: Gaurav Waratkar at IIT,Bombay P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/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., 2021, JApA, 42, 73) showed the detection of a long GRB 230320B which was also detected by Fermi GBM (TrigNum: 701039550), CALET (ID Num: 1363381768) and GECAM (TrigNum: 163). The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-03-20 21:12:27.50 UTC. The measured peak count rate associated with the burst is 415 (+48, -33) counts/s above the background in the combined data of three quadrants (out of four), with a total of 1976 (+332, -251) counts. The local mean background count rate was 360 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 11.27 (+6, -4) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-03-20 21:12:26.59 UTC. The measured peak count rate associated with the burst is 377 (+80, -44) counts/s above the background in the combined data of all quadrants, with a total of 1527 (+371, -423) counts. The local mean background count rate was 1564 (+4, -4) counts/s. We measure a T90 of 12.92 (+8, -4) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb [1] Links: ------ [1] http://astrosat.iucaa.in/czti/?q=grb //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33499 SUBJECT: GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV DATE: 23/03/21 23:43:53 GMT FROM: Aaron Tohuvavohu at U Toronto Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto) report: Swift/BAT did not localize GRB 230320B onboard (T0: 2023-03-20T21:12:25 UTC, Fermi/GBM trig 701039550, CALET trig 1363381768, GECAM trig 163, AstroSat/CZTI GCN 33492). The Fermi, CALET and GECAM notices, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 12.04 in a 4.096 s analysis time bin. The Fermi/GBM localization is consistent with being outside the BAT FOV. See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33501 SUBJECT: GRB 230320B: CALET Gamma-Ray Burst Monitor detection DATE: 23/03/22 04:03:08 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET T. Tamura (Kanagawa U), A. Yoshida, T. Sakamoto, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu (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 long GRB 230320B (AstroSat CZTI detection: Navaneeth et al., GCN Circ 33492) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 21:12:22.70 UTC on 20 March 2023 (http://cgbm.calet.jp/cgbm_trigger/flight/1363381768/index.html). The burst signal was seen by only the SGM detector. The burst light curve shows a single pulse that starts at T+2.4 sec, peaks at T+3.5 sec, and ends at T+20.3 sec. The T90 and T50 durations measured by the SGM data are 16.5 +/- 4.0 sec and 5.0 +/- 1.0 sec (40-1000 keV), respectively. The ground-processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1363381768/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33503 SUBJECT: GRB 230320B: GRBAlpha detection DATE: 23/03/22 16:38:18 GMT FROM: Marianna Dafcikova at Masaryk University <500025@mail.muni.cz> M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration. The long-duration GRB 230320B (AstroSat/CZTI detection: GCN 33492; Swift/BAT-GUANO detection: GCN 33499; CALET/CGBM detection: GCN 33501; Fermi/GBM detection: trigger no. 701039550; GECAM-B detection: trigger no. 163; Konus/Wind detection at 2023-03-20 21:12:25.277 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020). The detection was confirmed at the peak time 2023-03-20 21:12:27 UTC. The T90 duration measured by GRBAlpha is 26 s and the overall significance during T90 reaches 22.5 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB230320B_GCN.pdf All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33515 SUBJECT: GRB 230320B: Fermi GBM Observation DATE: 23/03/24 21:32:11 GMT FROM: Sarah Dalessi at UAH S. Dalessi (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 21:12:25 UT on 20 March 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230320B (trigger 701039550/230320884). which was also detected by AstroSat (P K. Navaneeth et al. 2023, GCN 33492), Swift/BAT-GUANO (S. Ronchini et al. 2023, GCN 33499) CALET (T. Tamura et al. 2023, GCN 33501), and GRBAlpha (M. Dafcikova et al. 2023, GCN 33503). The on-ground calculated location, using the GBM trigger data, is RA = 28.11, DEC = 68.88 (J2000 degrees, equivalent to 01 h 52 m, 68 d 53’ ), with a statistical uncertainty of 2.6 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ). The angle from the Fermi LAT boresight is 140 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0+0.003 to T0+15.616 s is best fit by a power law function with an exponential high-energy cutoff.The power law index is -0.30 +/- 0.09 and the cutoff energy, parameterized as Epeak = 186 +/- 8 keV. The event fluence (10-1000 keV) in this time interval is (1.02 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0 s in the 10-1000 keV band is 12.7 +/- 0.6 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"