//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32840 SUBJECT: LAT GRB221025.04: Global MASTER-Net observations report DATE: 22/10/25 08:55:10 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the LAT GRB221025.04 (trigger No 688352303,08h 53m 31.20s , +10d 59m 24.0s, R=1.26) errorbox 73 sec after trigger time at 2022-10-25 00:59:31 UT, with upper limit up to 18.8 mag. The observations began at zenith distance = 49 deg. The sun altitude is -29.1 deg. The galactic latitude b = 33 deg., longitude l = 217 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2133296 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 78 | 2022-10-25 00:59:31 | MASTER-Kislovodsk | (08h 48m 26.64s , +10d 04m 09.5s) | C | 10 | 16.8 | 113 | 2022-10-25 00:59:31 | MASTER-Kislovodsk | (08h 48m 26.64s , +10d 04m 09.2s) | C | 80 | 17.7 | Coadd 78 | 2022-10-25 00:59:31 | MASTER-Kislovodsk | (08h 52m 50.67s , +09d 40m 31.3s) | C | 10 | 16.6 | 113 | 2022-10-25 01:00:01 | MASTER-Kislovodsk | (08h 48m 32.72s , +10d 03m 07.0s) | C | 20 | 16.5 | 114 | 2022-10-25 01:00:01 | MASTER-Kislovodsk | (08h 52m 56.62s , +09d 39m 27.4s) | C | 20 | 16.6 | 159 | 2022-10-25 01:00:41 | MASTER-Kislovodsk | (08h 48m 26.80s , +10d 02m 05.3s) | C | 30 | 17.0 | 159 | 2022-10-25 01:00:41 | MASTER-Kislovodsk | (08h 52m 50.65s , +09d 38m 25.1s) | C | 30 | 17.4 | 214 | 2022-10-25 01:01:31 | MASTER-Kislovodsk | (08h 48m 32.76s , +10d 02m 05.4s) | C | 40 | 17.3 | 214 | 2022-10-25 01:01:32 | MASTER-Kislovodsk | (08h 52m 56.63s , +09d 38m 24.8s) | C | 40 | 17.8 | 278 | 2022-10-25 01:02:31 | MASTER-Kislovodsk | (08h 48m 30.73s , +10d 03m 46.4s) | C | 50 | 17.5 | 278 | 2022-10-25 01:02:31 | MASTER-Kislovodsk | (08h 52m 54.63s , +09d 40m 05.3s) | C | 50 | 18.0 | 354 | 2022-10-25 01:03:42 | MASTER-Kislovodsk | (08h 48m 30.83s , +10d 02m 32.6s) | C | 60 | 17.4 | 354 | 2022-10-25 01:03:42 | MASTER-Kislovodsk | (08h 52m 54.73s , +09d 38m 51.0s) | C | 60 | 17.7 | 1265 | 2022-10-25 01:17:53 | MASTER-Kislovodsk | (08h 42m 33.57s , +12d 20m 52.2s) | C | 180 | 18.0 | 1265 | 2022-10-25 01:17:53 | MASTER-Kislovodsk | (08h 47m 01.30s , +11d 57m 15.5s) | C | 180 | 17.9 | 1466 | 2022-10-25 01:21:14 | MASTER-Kislovodsk | (08h 46m 55.31s , +11d 56m 45.6s) | C | 180 | 18.1 | 1466 | 2022-10-25 01:21:14 | MASTER-Kislovodsk | (08h 42m 27.46s , +12d 20m 21.1s) | C | 180 | 18.1 | 1667 | 2022-10-25 01:24:34 | MASTER-Kislovodsk | (08h 42m 27.47s , +12d 21m 25.0s) | C | 180 | 18.0 | 1667 | 2022-10-25 01:24:34 | MASTER-Kislovodsk | (08h 46m 55.52s , +11d 57m 50.4s) | C | 180 | 17.8 | 1867 | 2022-10-25 01:27:55 | MASTER-Kislovodsk | (08h 42m 33.31s , +12d 20m 29.2s) | C | 180 | 17.8 | 1867 | 2022-10-25 01:27:55 | MASTER-Kislovodsk | (08h 47m 01.68s , +11d 56m 55.0s) | C | 180 | 17.6 | 3748 | 2022-10-25 01:59:16 | MASTER-Kislovodsk | (08h 42m 43.32s , +12d 21m 59.0s) | C | 180 | 18.5 | 3748 | 2022-10-25 01:59:16 | MASTER-Kislovodsk | (08h 47m 04.36s , +11d 58m 23.2s) | C | 180 | 18.3 | 4194 | 2022-10-25 02:06:42 | MASTER-Kislovodsk | (08h 42m 34.56s , +12d 22m 29.3s) | C | 180 | 18.1 | 4194 | 2022-10-25 02:06:42 | MASTER-Kislovodsk | (08h 46m 57.79s , +11d 58m 06.3s) | C | 180 | 18.8 | 5067 | 2022-10-25 02:21:15 | MASTER-Kislovodsk | (08h 42m 37.61s , +12d 22m 18.4s) | C | 180 | 18.3 | 5067 | 2022-10-25 02:21:15 | MASTER-Kislovodsk | (08h 47m 02.20s , +11d 57m 59.1s) | C | 180 | 18.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32843 SUBJECT: GRB 221025A: Fermi-LAT detection DATE: 22/10/25 11:43:09 GMT FROM: Makoto Arimoto at Tokyo Inst of Tech Arimoto M. (Kanazawa University) Pillera R. (Politecnico and INFN Bari), and Maheso D. (Johannesburg Univ.) report on behalf of the Fermi-LAT team: At 00:58:18.42 on October, 25, 2022 Fermi-LAT detected high-energy emission from GRB 221025A, GBM trigger 221025041 / 688352303 at 00:58:18.42 UT. The best LAT on-ground location is found to be RA, Dec = 133.4, 11.0 (J2000) with an error radius of 1.3 deg (90 % containment, statistical error only). This was 45 deg from the LAT boresight at the time of the trigger. The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance. The 100 MeV - 1 GeV photon flux in the time interval 0-200 s after the GBM trigger is (2.1 +/- 0.6)E-05 ph/cm2/s. The estimated integrated photon index above 100 MeV is -2.3 +/- 0.3. The highest-energy photon is a 1.3 GeV event with 93% probability which is observed 3 seconds after the GBM trigger. A Swift ToO has been requested for this burst. The Fermi-LAT point of contact for this burst is Dimakatso Jeannett Maheso (d.j.maheso@gmail.com). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32851 SUBJECT: GRB 221025A: Fermi GBM Observation DATE: 22/10/25 16:52:20 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 00:58:18 UT on 25 October 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 221025A (trigger 688352303 / 221025040). which was also detected by Fermi-LAT (Arimoto M. et al. 2022, GCN 32843). The Fermi GBM on-ground location is consistent with the Fermi-LAT position. The on-ground calculated location, using the GBM trigger data, is RA = 128.9, DEC = +2.2 (J2000 degrees, equivalent to 08h 36m, +02d 12'), with an uncertainty of 6.8 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 48.5 degrees. The GBM light curve consists of a single pulse with a duration (T90) of about 0.4 s (50-300 keV). The time-averaged spectrum from T0+0.0 to T0+0.8 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.4 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 1680 +/- 345 keV. The event fluence (10-1000 keV) in this time interval is (1.7 +/- 0.1)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.3 s in the 10-1000 keV band is 13.3 +/- 0.9 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/" //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32853 SUBJECT: GRB 221025A: AstroSat CZTI detection DATE: 22/10/26 13:42:23 GMT FROM: Gaurav Waratkar at IIT,Bombay R. Gopalakrishnan (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 short GRB 221025A which was also detected by Fermi-GBM (Wood et al,. GCN 32851) and Fermi-LAT (Arimoto et al,. GCN 32843). The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2022-10-25 00:58:18.6 UTC. The measured peak count rate associated with the burst is 904 (+212, -102) counts/s above the background in the combined data of all quadrants, with a total of 313 (+62, -63) counts. The local mean background count rate was 435 (+8, -12) counts/s. Using cumulative rates, we measure a T90 of 0.45 (+0.6, -0.2) s. It was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it. 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, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32865 SUBJECT: IPN triangulation of GRB 221025A (short) DATE: 22/10/27 14:34:24 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report: The short-duration GRB 221025A (Fermi-LAT detection: Arimoto et al., GCN Circ. 32843; Fermi-GBM detection: Wood and Meegan, GCN Circ. 32851; AstroSat-CZTI detection: Gopalakrishnan et al., GCN Circ. 32853) was detected by Fermi (GBM trigger 688352303), INTEGRAL (SPI-ACS), Konus-Wind, AstroSat (CZTI), and GECAM-B (trigger tn221025_005818_fb) at about 3498 s UT (00:58:18). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 134.373 (08h 57m 29s) +13.068 (+13d 04' 07") Corners: 133.601 (08h 54m 24s) +10.772 (+10d 46' 20") 133.259 (08h 53m 02s) +10.806 (+10d 48' 20") 135.172 (09h 00m 41s) +15.363 (+15d 21' 46") 135.522 (09h 02m 05s) +15.330 (+15d 19' 48") --------------------------------------------- The error box area is 1.6 sq. deg, and its maximum dimension is 5.03 deg (the minimum one is 19.44 arcmin). The Sun distance was 78 deg. This localization may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi-GBM final localization (glg_healpix_all_bn221025040_v00). A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB221025_T03498/IPN/ The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.