June 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[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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[vsnet-grb-info 38851] Konus-Wind detection of GRB 250620C
by GCN Circulars 22 Jun '25

22 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40810 SUBJECT: Konus-Wind detection of GRB 250620C DATE: 25/06/22 10:03:09 GMT FROM: Dmitry Svinkin at Ioffe Institute <dmitrysvinkin(a)gmail.com> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The bright,long-duration GRB 250620C (Fermi-GBM detection: The Fermi GBM team, GCN 40794; Mukherjee, GCN 40799; SVOM-GRM detection: Wang et al., GCN 40807; IPN triangulation: Svinkin et al., GCN 40809) triggered Konus-Wind at T0=58026.172 s UT (16:07:06.172). The burst light curve shows a multipeaked structure which starts at ~T0-0.2 s and has a total duration of ~39 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/GRB250620_T58026/ As observed by Konus-Wind, the burst had a fluence of 7.87(-0.47,+0.43)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.344 s, of 4.05(-0.28,+0.28)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+39.424 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.00(-0.03,+0.03), the high energy photon index beta = -2.83(-0.42,+0.21), the peak energy Ep = 363(-17,+19) keV (chi2 = 116/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+1.536 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.71(-0.05,+0.05), the high energy photon index beta = -2.44(-0.14,+0.12), the peak energy Ep = 618(-45,+47) keV (chi2 = 85/59 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/40810. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38850] IPN triangulation of GRB 250620С (long/bright)
by GCN Circulars 22 Jun '25

22 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40809 SUBJECT: IPN triangulation of GRB 250620С (long/bright) DATE: 25/06/22 09:58:12 GMT FROM: Dmitry Svinkin at Ioffe Institute <dmitrysvinkin(a)gmail.com> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, 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, and S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu, and J. DeLaunay on behalf of the Swift-BAT team, report: The bright long-duration GRB 250620C (Fermi-GBM detection: The Fermi GBM team, GCN 40794; Mukherjee, GCN 40799; SVOM-GRM detection: Wang et al., GCN 40807) was detected by Fermi (GBM trigger 772128434), Swift (BAT), Konus-Wind, and SVOM (GRM) at about 58030 s UT (16:07:10). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose area is 17.6 sq. deg, and its maximum dimension is 25.5 deg (the minimum one is 51.0 arcmin). The Sun distance was ~50 deg. This localization may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi-GBM (GCN 40794) and BALROG (https://grb.mpe.mpg.de/grb/GRB250620672/?data_version=tte_v00) localizations. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB250620_T58026/IPN The HEALPix triangulation map is the multi-order HEALPix in units of probability density. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/40809. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38849] GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
by GCN Circulars 22 Jun '25

22 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40808 SUBJECT: GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst DATE: 25/06/22 06:07:38 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Frédéric Piron (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a short burst GRB 250621B (SVOM trigger reference: sb25062104) at 2025-06-21T09:13:47.100 UTC (T0), which is also detected by Fermi/GBM (TrigNum 772190032). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a narrow spike with a T90 of 0.11 +0.02/-0.03 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250621B.png The SVOM/GRM on-ground localization of this burst is (J2000): RA: 273.9 deg DEC: -24.8 deg Error: 2.9 deg (1sigma, statistical only) We caution that the calibration of SVOM/GRM is undergoing and this localization is subject to systematic errors. In addition, the position of this burst, as determined by GRM, is located at about 8 degrees from the SVOM optical axis, but ECLAIRs was not collecting data at the time of this burst. With this localization, the time-averaged spectrum from T0-0.3 to T0+0.2 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.05 +0.25/-0.27 and the cutoff energy, parameterized as Epeak, is 31 +/- 3 keV. The event fluence (10-1000 keV) in this time interval is (3.79 +/-0.15)E-07 erg/cm^2. We note that the localization of this burst is relatively close to the Galactic disk and compatible with the position of SGR 1806-20, as well as the hardness and duration all suggest a magnetar X-ray burst. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/40808. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38848] GRB 250620C: SVOM/GRM observation
by GCN Circulars 22 Jun '25

22 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40807 SUBJECT: GRB 250620C: SVOM/GRM observation DATE: 25/06/22 05:55:58 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Ulysse Jacob (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a bright burst GRB 250620C (SVOM trigger reference: sb25062006) at 2025-06-20T16:07:10.100 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#40794). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a narrow spike with a T90 of 30.1 +/-1.5 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250620C.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 142.6, DEC= 55.0, GCN#40794), is located at about 161 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-1 to T0+40 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.22 +0.13/-0.12 and the cutoff energy, parameterized as Epeak, is 502 +74/-55 keV. The event fluence (10-1000 keV) in this time interval is (9.15 +0.26/-0.28)E-07 erg/cm^2. The localization of GRB 250620C in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/grb250620C_amati.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/40807. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38847] GRB 250620A: SVOM/GRM observation of a short burst
by GCN Circulars 22 Jun '25

22 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40806 SUBJECT: GRB 250620A: SVOM/GRM observation of a short burst DATE: 25/06/22 05:55:18 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Ulysse Jacob (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a bright burst GRB 250620A (SVOM trigger reference: sb25062002) at 2025-06-20T08:05:19 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#40791) and Swift/BAT (James DeLaunay et al., GCN#40796). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a narrow spike with a T90 of 0.15 +/-0.05 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250620A.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 46.2, DEC= 65.8, GCN#40791), is located at about 111 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-0.2 to T0 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.64 +0.25/-0.19 and the cutoff energy, parameterized as Epeak, is 1310 +1780/-780 keV. The event fluence (10-1000 keV) in this time interval is (8.36 +0.89/-0.87)E-07 erg/cm^2. The localization of GRB 250620A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/grb250620A_amati.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/40806. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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