- vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 38861] GRB 241018A: Maidanak optical observations
by GCN Circulars 25 Jun '25

25 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40820 SUBJECT: GRB 241018A: Maidanak optical observations DATE: 25/06/25 10:30:21 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), N. Pankov (HSE,IKI), O. Burhonov (UBAI), Sh. Ehgamberdiev (UBAI) report on behalf of GRB IKI FuN: We observed the field of GRB 241018A (SVOM team, GCN 37812) with AZT-22 1.5m telescope of Maidanak observatory in R-filter on 2024-10-18 (UT) 20:12:00 and in I-filter on 2024-10-19 (UT) 19:07:59 under very good weather conditions (seeing ~1"). The afterglow (SVOM/VT: GCN 37819; Swift XRT: Osborne et al., GCN 37823, Optical NOT: Malesani et al. GCN 37821; SVOM/VT commissioning team, GCN 37826; SVOM/C-GFT team, GCN 37841) is marginally detected in stacked images of 1 hour total exposure each. Preliminary photometry of the source is the following: Date UT start t-T0 Exp. Filter OT Err. UL(3 sigma) (mid, days) (s) 2024-10-18 20:12:00 0.37616 60x60 R 22.2 0.3 22.3 2024-10-19 19:07:59 1.33287 61x60 I 22.4 0.3 22.4 The photometry is based on nearby USNO-B1.0 stars: USNO-B_id RA Dec R2 I 1330-00124435 04:32:02.23 +43:02:33.2 17.00 16.39 1330-00124413 04:32:00.31 +43:01:30.1 16.80 15.94 1330-00124450 04:32:03.82 +43:01:22.9 16.55 16.24 The result is consistent with previously reported optical non-detection (Turpin et al., GCN 37818; Ferro et al., GCN 37822; Song et al., GCN 37824; Mohan et al., GCN 37825; Pankov et al., GCN 37827; Fernandez-Garcia et al., GCN 37828; Liu et al., GCN 37830; Ror et al., GCN 37837). View this GCN Circular online at https://gcn.nasa.gov/circulars/40820. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38860] GRB 250620C: AstroSat CZTI detection
by GCN Circulars 25 Jun '25

25 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40819 SUBJECT: GRB 250620C: AstroSat CZTI detection DATE: 25/06/25 07:20:43 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> S.Salunke (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 and bright GRB 250620C which was also detected by Fermi/GBM (Fermi GBM team, GCN Circ. 40794), SVOM/GRM (Chen-Wei Wang et al, GCN Circ. 40807), and Konus-Wind (Svinkin et al, GCN Circ. 40810). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-06-20 16:07:11.50 UTC. The measured peak count rate associated with the burst is 1004 (+55, -46) counts/s above the background in the combined data of two quadrants (out of four), with a total of 8579 (+269, -224) counts. The local mean background count rate was 150 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 31.3 (+0.3, -0.4) s. In the preliminary analysis, we find 1018 Compton events associated with this event. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-06-20 16:07:10.63 UTC. The measured peak count rate associated with the burst is 4717 (+120, -137) counts/s above the background in the combined data of all quadrants, with a total of 17904 (+519, -667) counts. The local mean background count rate was 1222 (+6, -5) counts/s. We measure a T90 of 31 (+1, -2) 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 View this GCN Circular online at https://gcn.nasa.gov/circulars/40819. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38859] Fermi GRB 250624A: Global MASTER-Net observations report
by GCN Circulars 24 Jun '25

24 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40818 SUBJECT: Fermi GRB 250624A: Global MASTER-Net observations report DATE: 25/06/24 20:30:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 250624A ( Fermi GBM team, GCN 40817) errorbox 542 sec after notice time and 573 sec after trigger time at 2025-06-24 19:45:55 UT, with upper limit up to 14.4 mag. Observations started at twilight. The observations began at zenith distance = 57 deg. The sun altitude is -8.0 deg. The galactic latitude b = -46 deg., longitude l = 121 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2915767 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 574 | 2025-06-24 19:45:55 | MASTER-Tunka | (00h 36m 20.26s , +16d 05m 54.9s) | C | 1 | 14.4 | 584 | 2025-06-24 19:46:05 | MASTER-Tunka | (00h 36m 20.23s , +16d 05m 54.7s) | C | 1 | 14.4 | 590 | 2025-06-24 19:46:10 | MASTER-Tunka | (00h 36m 20.23s , +16d 05m 54.6s) | C | 1 | 14.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40818. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38858] GRB 250624A: Fermi GBM Final Real-time Localization
by GCN Circulars 24 Jun '25

24 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40817 SUBJECT: GRB 250624A: Fermi GBM Final Real-time Localization DATE: 25/06/24 19:46:55 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 19:36:21 UT on 24 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250624A (trigger 772486586.849764 / 250624817). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 10.6, Dec = 16.6 (J2000 degrees, equivalent to J2000 00h 42m, 16d 36'), with a statistical uncertainty of 5.3 degrees. The angle from the Fermi LAT boresight is 56.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250624817/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250624817/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250624817/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40817. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38857] sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
by GCN Circulars 24 Jun '25

24 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40816 SUBJECT: sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis DATE: 25/06/24 11:04:07 GMT FROM: ogodet(a)irap.omp.eu Authors: O. Godet (IRAP), N. Dagoneau (CEA), F. Cangemi (APC), M. Brunet (IRAP), L. Zhang (IHEP), Y.-D. Hu (GXU), X.-L. Chen (YNU) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of the event sb25061207 that we confirm to be a GRB (GRB 250612D) based on the detection of a fading afterglow in both visible (GCN #40707) and X-rays (GCN #40718). The burst that triggered ECLAIRs onboard (GCN #40697) displays a faint and soft emission with most photons emitted below 20 keV. The duration of this event is around 32 s in the 4-20 keV energy band. The time-averaged spectrum from T0-32s to T0 (T0 = 2025-06-12T10:27:22 UTC) in the energy range 5-20 keV is best fitted by a powerlaw model with a photon index = 1.7 +/-0.3. With this model, the total 4-120 keV fluence is (7.4 +0.3/-4.2)e-7 erg/cm^2. All the quoted errors are at the 68% confidence level. We note that the calibration of SVOM/ECLAIRs is undergoing thus these results are preliminary. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic Universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Olivier Godet (IRAP) (ogodet at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/40816. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38856] Fermi GRB 250623A: Global MASTER-Net observations report
by GCN Circulars 23 Jun '25

23 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40815 SUBJECT: Fermi GRB 250623A: Global MASTER-Net observations report DATE: 25/06/23 20:15:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250623A ( Fermi GBM team, GCN 40814) errorbox 12254 sec after notice time and 12285 sec after trigger time at 2025-06-23 19:35:57 UT, with upper limit up to 19.6 mag. The observations began at zenith distance = 26 deg. The sun altitude is -48.5 deg. The galactic latitude b = 38 deg., longitude l = 359 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2914124 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 12315 | 2025-06-23 19:35:57 | MASTER-SAAO | (15h 27m 52.76s , -06d 33m 00.0s) | C | 60 | 19.2 | 12315 | 2025-06-23 19:35:57 | MASTER-SAAO | (15h 26m 04.67s , -06d 17m 23.3s) | C | 60 | 19.2 | 12408 | 2025-06-23 19:37:30 | MASTER-SAAO | (15h 35m 45.45s , -06d 34m 17.7s) | C | 60 | 19.2 | 12408 | 2025-06-23 19:37:30 | MASTER-SAAO | (15h 33m 57.55s , -06d 18m 40.9s) | C | 60 | 19.3 | 12502 | 2025-06-23 19:39:03 | MASTER-SAAO | (15h 23m 10.48s , -04d 22m 29.2s) | C | 60 | 19.5 | 12595 | 2025-06-23 19:40:36 | MASTER-SAAO | (15h 32m 55.26s , -04d 39m 53.0s) | C | 60 | 19.3 | 12595 | 2025-06-23 19:40:36 | MASTER-SAAO | (15h 31m 07.96s , -04d 24m 16.4s) | C | 60 | 19.3 | 12689 | 2025-06-23 19:42:11 | MASTER-SAAO | (15h 31m 46.60s , -08d 26m 56.3s) | C | 60 | 19.5 | 12689 | 2025-06-23 19:42:11 | MASTER-SAAO | (15h 29m 58.43s , -08d 11m 19.1s) | C | 60 | 19.5 | 12783 | 2025-06-23 19:43:44 | MASTER-SAAO | (15h 39m 47.59s , -08d 26m 17.1s) | C | 60 | 19.3 | 12783 | 2025-06-23 19:43:44 | MASTER-SAAO | (15h 37m 59.47s , -08d 10m 39.5s) | C | 60 | 19.4 | 12876 | 2025-06-23 19:45:18 | MASTER-SAAO | (15h 40m 02.82s , -04d 40m 16.4s) | C | 60 | 19.4 | 12876 | 2025-06-23 19:45:18 | MASTER-SAAO | (15h 38m 15.65s , -04d 24m 39.4s) | C | 60 | 19.5 | 12969 | 2025-06-23 19:46:51 | MASTER-SAAO | (15h 48m 06.97s , -04d 40m 30.1s) | C | 60 | 19.3 | 12969 | 2025-06-23 19:46:51 | MASTER-SAAO | (15h 46m 19.81s , -04d 24m 52.8s) | C | 60 | 19.4 | 13062 | 2025-06-23 19:48:24 | MASTER-SAAO | (15h 27m 56.33s , -06d 31m 53.7s) | C | 60 | 19.3 | 13062 | 2025-06-23 19:48:24 | MASTER-SAAO | (15h 26m 08.67s , -06d 16m 16.9s) | C | 60 | 19.4 | 13156 | 2025-06-23 19:49:57 | MASTER-SAAO | (15h 35m 55.61s , -06d 33m 31.4s) | C | 60 | 19.3 | 13156 | 2025-06-23 19:49:57 | MASTER-SAAO | (15h 34m 07.99s , -06d 17m 54.2s) | C | 60 | 19.4 | 13249 | 2025-06-23 19:51:30 | MASTER-SAAO | (15h 25m 07.12s , -04d 37m 46.5s) | C | 60 | 19.3 | 13249 | 2025-06-23 19:51:30 | MASTER-SAAO | (15h 23m 19.89s , -04d 22m 09.6s) | C | 60 | 19.6 | 13342 | 2025-06-23 19:53:04 | MASTER-SAAO | (15h 33m 00.14s , -04d 38m 44.7s) | C | 60 | 19.3 | 13342 | 2025-06-23 19:53:04 | MASTER-SAAO | (15h 31m 12.86s , -04d 23m 07.5s) | C | 60 | 19.4 | 13435 | 2025-06-23 19:54:37 | MASTER-SAAO | (15h 31m 52.38s , -08d 25m 39.2s) | C | 60 | 19.4 | 13435 | 2025-06-23 19:54:37 | MASTER-SAAO | (15h 30m 04.09s , -08d 10m 01.9s) | C | 60 | 19.5 | 13528 | 2025-06-23 19:56:10 | MASTER-SAAO | (15h 40m 00.69s , -08d 27m 01.6s) | C | 60 | 19.3 | 13528 | 2025-06-23 19:56:10 | MASTER-SAAO | (15h 38m 12.35s , -08d 11m 24.2s) | C | 60 | 19.5 | 13621 | 2025-06-23 19:57:43 | MASTER-SAAO | (15h 40m 11.81s , -04d 40m 00.8s) | C | 60 | 19.3 | 13621 | 2025-06-23 19:57:43 | MASTER-SAAO | (15h 38m 24.33s , -04d 24m 24.1s) | C | 60 | 19.6 | 13714 | 2025-06-23 19:59:16 | MASTER-SAAO | (15h 48m 14.27s , -04d 40m 05.3s) | C | 60 | 19.4 | 13714 | 2025-06-23 19:59:16 | MASTER-SAAO | (15h 46m 26.76s , -04d 24m 28.5s) | C | 60 | 19.5 | 13808 | 2025-06-23 20:00:49 | MASTER-SAAO | (15h 28m 03.37s , -06d 31m 40.0s) | C | 60 | 19.4 | 13808 | 2025-06-23 20:00:49 | MASTER-SAAO | (15h 26m 15.29s , -06d 16m 03.5s) | C | 60 | 19.6 | 13906 | 2025-06-23 20:02:28 | MASTER-SAAO | (15h 36m 02.97s , -06d 33m 23.3s) | C | 60 | 19.4 | 13906 | 2025-06-23 20:02:28 | MASTER-SAAO | (15h 34m 14.81s , -06d 17m 46.2s) | C | 60 | 19.5 | 13999 | 2025-06-23 20:04:01 | MASTER-SAAO | (15h 25m 14.02s , -04d 37m 33.0s) | C | 60 | 19.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40815. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38855] GRB 250623A: Fermi GBM Final Real-time Localization
by GCN Circulars 23 Jun '25

23 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40814 SUBJECT: GRB 250623A: Fermi GBM Final Real-time Localization DATE: 25/06/23 16:21:45 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 16:11:12 UT on 23 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250623A (trigger 772387877.080294 / 250623674). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 233.4, Dec = -6.0 (J2000 degrees, equivalent to J2000 15h 33m, -6d 00'), with a statistical uncertainty of 10.2 degrees. The angle from the Fermi LAT boresight is 68.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250623674/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250623674/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250623674/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40814. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38854] GRB 250521A: VZLUSAT-2 detection
by GCN Circulars 23 Jun '25

23 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40813 SUBJECT: GRB 250521A: VZLUSAT-2 detection DATE: 25/06/23 15:09:37 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU) -- the VZLUSAT-2/GRB payload collaboration. The long-duration GRB 250521A (Fermi/GBM detection: GCN 40508; GRBAlpha detection: GCN 40541; Wind/Konus detection trigger at 2025-05-21 04:27:04.888 UTC) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/). The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2025-05-21 04:27:09 (04:27:02) UTC. The T90 duration is 33 s (35 s) and the significance during T90 reaches 10 sigma (15 sigma) for detector unit no. 0 (no. 1). The light curve obtained by VZLUSAT-2 is available here: https://vzlusat2.konkoly.hu/static/share/GRB250521A_GCN_VZLUSAT2.pdf All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/ The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral. View this GCN Circular online at https://gcn.nasa.gov/circulars/40813. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38853] GRB 250617B: Swift-BAT refined analysis
by GCN Circulars 23 Jun '25

23 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40812 SUBJECT: GRB 250617B: Swift-BAT refined analysis DATE: 25/06/23 11:39:14 GMT FROM: Takanori Sakamoto at AGU <tsakamoto(a)phys.aoyama.ac.jp> S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-273 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250617B (trigger #1325580) (Page, et al., GCN Circ. 40760). The BAT ground-calculated position is RA, Dec = 332.883, 32.721 deg which is RA(J2000) = 22h 11m 31.8s Dec(J2000) = +32d 43' 14.5" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 10%. The mask-weighted light curve shows two peaks. The emission starts at T-30 sec, peaks at T+1 sec, and ends at T+18 sec. T90 (15-350 keV) is 36.5 +- 6.9 sec (estimated error including systematics). The time-averaged spectrum from T-29.32 to T+14.30 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.13 +- 0.22. The fluence in the 15-150 keV band is 2.3 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.19 sec in the 15-150 keV band is 2.9 +- 0.8 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1325580 View this GCN Circular online at https://gcn.nasa.gov/circulars/40812. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38852] Fermi trigger No 772190032: Global MASTER-Net observations report
by GCN Circulars 22 Jun '25

22 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40811 SUBJECT: Fermi trigger No 772190032: Global MASTER-Net observations report DATE: 25/06/22 17:45:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB250621.38 (trigger No 772190032,18h 06m 48.00s , -20d 49m 58.8s, R=13.3) errorbox 41094 sec after notice time and 41126 sec after trigger time at 2025-06-21 20:39:13 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 17 deg. The sun altitude is -62.0 deg. The galactic latitude b = -1 deg., longitude l = 10 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2911222 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 41157 | 2025-06-21 20:39:13 | MASTER-SAAO | (17h 03m 51.42s , -21d 48m 23.9s) | C | 60 | 18.5 | 41250 | 2025-06-21 20:40:46 | MASTER-SAAO | (17h 12m 24.87s , -21d 47m 48.3s) | C | 60 | 18.4 | 43099 | 2025-06-21 21:11:35 | MASTER-SAAO | (17h 04m 13.21s , -21d 48m 47.1s) | C | 60 | 18.5 | 43192 | 2025-06-21 21:13:08 | MASTER-SAAO | (17h 12m 43.81s , -21d 47m 46.4s) | C | 60 | 18.3 | 45253 | 2025-06-21 21:47:29 | MASTER-SAAO | (17h 04m 32.28s , -21d 47m 18.3s) | C | 60 | 18.5 | 45348 | 2025-06-21 21:49:05 | MASTER-SAAO | (17h 12m 59.51s , -21d 48m 45.5s) | C | 60 | 18.3 | 46601 | 2025-06-21 22:09:58 | MASTER-SAAO | (17h 04m 34.91s , -21d 46m 48.7s) | C | 60 | 18.5 | 46694 | 2025-06-21 22:11:31 | MASTER-SAAO | (17h 13m 09.50s , -21d 46m 18.7s) | C | 60 | 18.3 | 47940 | 2025-06-21 22:32:16 | MASTER-SAAO | (17h 04m 45.05s , -21d 47m 05.2s) | C | 60 | 18.5 | 48033 | 2025-06-21 22:33:50 | MASTER-SAAO | (17h 13m 21.76s , -21d 46m 08.2s) | C | 60 | 18.4 | 50042 | 2025-06-21 23:07:19 | MASTER-SAAO | (17h 04m 55.78s , -21d 46m 23.4s) | C | 60 | 18.6 | 50136 | 2025-06-21 23:08:52 | MASTER-SAAO | (17h 13m 27.52s , -21d 45m 19.7s) | C | 60 | 18.3 | 115062 | 2025-06-22 17:10:59 | MASTER-SAAO | (18h 11m 33.03s , -24d 48m 18.7s) | C | 60 | 17.0 | 115278 | 2025-06-22 17:14:34 | MASTER-SAAO | (18h 11m 29.34s , -24d 47m 56.5s) | C | 60 | 16.9 | 115928 | 2025-06-22 17:25:25 | MASTER-SAAO | (18h 11m 32.62s , -24d 47m 32.4s) | C | 60 | 16.8 | 116140 | 2025-06-22 17:28:57 | MASTER-SAAO | (18h 11m 32.10s , -24d 48m 31.6s) | C | 60 | 16.9 | 116348 | 2025-06-22 17:32:25 | MASTER-SAAO | (18h 11m 28.31s , -24d 48m 25.1s) | C | 60 | 16.9 | 116555 | 2025-06-22 17:35:52 | MASTER-SAAO | (18h 11m 24.50s , -24d 47m 38.3s) | C | 60 | 16.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40811. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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