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

[vsnet-grb-info 38580] EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
by GCN Circulars 26 May '25

26 May '25

TITLE: GCN CIRCULAR NUMBER: 40548 SUBJECT: EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate DATE: 25/05/26 15:19:07 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> M. J. Liu, D. H. Zhao (NAO, CAS), Y. Wang(PMO, CAS), W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient candidate at 2025-05-25T23:18:23 (UTC) by the Wide-field X-ray Telescope (WXT) on board Einstein Probe (EP), which we designated EP J1350.0-8622. This source was discovered through on-ground analysis of WXT telemetry data. The WXT position of the source is R.A. = 207.494 deg, DEC = -86.373 deg (J2000) with an uncertainty of 2.6 arcmin in radius (90% C.L. statistical and systematic). The derived unabsorbed 0.5-4 keV flux by an absorbed power-law model is 6.8(+9.6/-6.8) x 10^-12 erg/cm^2/s with the column density fixed at the Galactic value of 8.2 x 10^20 cm^-2 and photon index fixed at 2. Within the WXT error circle, an X-ray source 1eRASS J135031.1-862323 was detected by eROSITA with a flux of 4.9 x 10^-14 erg/cm2/s (0.6-2.3 keV). A Gaia source Gaia DR3 5766213157904565376, likely a quasar, is 8.155 arcsec away from the eROSITA source. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/40548. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38579] EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
by GCN Circulars 24 May '25

24 May '25

TITLE: GCN CIRCULAR NUMBER: 40547 SUBJECT: EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation DATE: 25/05/24 07:03:12 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao (NAOC), Yulei, Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng (NAOC), Lei Huang (NAOC), Jianyan Wei (NAOC) report on behalf of the SVOM/C-GFT team: We observed the field of the X-ray transient WXT trigger 01709176712 from the Einstein Probe (Yang et al., GCN 40537) with LATIOS on SVOM/C-GFT. Observations started at 2025-05-23T12:52:03, ~7.54 mins after the trigger. A series of g, r, and i-band images were obtained over ~2.58 hr. Preliminary analysis shows that the flare star reported by Yang et al. (GCN 40537) and Neill et al. (GCN 40542) exhibited a g-band magnitude decline from 11.36 mag to 12.95 mag, with a color variation (g−i) of~ 0.73 mag (from −0.24 to +0.49) between 11 and 162 minutes post trigger. Magnitudes were calibrated with nearby Pan-STARRS1 stars and were not corrected for dust extinction. We thank the observation assistants Bowen Li and Shuai Liu at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec ×21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k×4k CMOS camera at the prime focus with a 1.28 deg × 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/40547. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38578] GRB 250520A: 3 GHz MeerKAT Detection
by GCN Circulars 24 May '25

24 May '25

TITLE: GCN CIRCULAR NUMBER: 40546 SUBJECT: GRB 250520A: 3 GHz MeerKAT Detection DATE: 25/05/24 00:23:36 GMT FROM: Genevieve Schroeder at Cornell University <genevieveschroeder(a)u.northwestern.edu> G. Schroeder (Cornell), L. Rhodes (TSI/McGill), W. Fong (Northwestern), A. J. Levan (Radboud and Warwick) report: We observed the location of the short-duration GRB 250520A (Eyles-Ferris et al., GCN 40491; SVOM/GRM Team, GCN 40495; Tembhurnikar et al., GCN 40497; Frederiks et al., GCN 40512; Asaoka et al., GCN 40519; Dafcikova et al., GCN 40540) with the MeerKAT radio telescope at 3.1 GHz for a total of 2 hours at a mid time of 2025 May 23 at 03:50 UT (3.05 days post burst). In preliminary analysis, we detect a ~3.4-sigma radio source with a flux density of ~18 microJy consistent with the position of the 10 GHz radio afterglow (Schroeder et al., GCN 40518; GCN 40545) and also with the X-ray afterglow (Goad et al., GCN 40494). Further observations are planned. We thank the staff at the South African Radio Astronomy Observatory for scheduling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40546. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38577] GRB 250520A: 10 GHz VLA Afterglow Confirmation
by GCN Circulars 24 May '25

24 May '25

TITLE: GCN CIRCULAR NUMBER: 40545 SUBJECT: GRB 250520A: 10 GHz VLA Afterglow Confirmation DATE: 25/05/24 00:21:19 GMT FROM: Genevieve Schroeder at Cornell University <genevieveschroeder(a)u.northwestern.edu> G. Schroeder (Cornell), W. Fong (Northwestern), T. Laskar (Utah) report: We re-observed the location of the short-duration GRB 250520A (Eyles-Ferris et al., GCN 40491; SVOM/GRM Team, GCN 40495; Tembhurnikar et al., GCN 40497; Frederiks et al., GCN 40512; Asaoka et al., GCN 40519; Dafcikova et al., GCN 40540) with the Karl G. Jansky Very Large Array (VLA) in C configuration under program 25A-063 (PI Schroeder) at a mid time of 2025 May 21 at 11:24 UT (3.36 days post-burst) for a total of 2.25 hours at a mean frequencies of 6 and 10 GHz. The radio source detected in the previous 10 GHz VLA observation at 1.28 days (Schroeder et al., GCN 40518) is no longer detected at 3.36 days, to a 3 sigma limit of 10 microJy. Given the fading of this source, and its positional coincidence with the XRT afterglow (Goad et al., GCN 40494), we consider it to be the radio afterglow of GRB 250520A. We thank the VLA staff for quickly approving and executing these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40545. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38576] Fermi GRB 250523A: Global MASTER-Net observations report
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40544 SUBJECT: Fermi GRB 250523A: Global MASTER-Net observations report DATE: 25/05/23 20:31:57 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-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 Fermi GRB 250523A ( Fermi GBM team, GCN 40538) errorbox 21017 sec after notice time and 21056 sec after trigger time at 2025-05-23 20:17:20 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 81 deg. The sun altitude is -25.3 deg. The galactic latitude b = -0 deg., longitude l = 145 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2879253 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 21087 | 2025-05-23 20:17:20 | MASTER-Kislovodsk | (03h 30m 46.09s , +56d 01m 35.6s) | C | 60 | 17.1 | 21175 | 2025-05-23 20:18:48 | MASTER-Kislovodsk | (03h 45m 14.18s , +56d 02m 05.0s) | C | 60 | 17.0 | 21462 | 2025-05-23 20:23:35 | MASTER-Kislovodsk | (03h 02m 54.34s , +56d 12m 15.7s) | C | 60 | 17.1 | 21545 | 2025-05-23 20:24:58 | MASTER-Kislovodsk | (03h 17m 09.58s , +56d 11m 13.2s) | C | 60 | 17.1 | 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/40544. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38575] Fermi trigger No 769611916: Global MASTER-Net observations report
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40543 SUBJECT: Fermi trigger No 769611916: Global MASTER-Net observations report DATE: 25/05/23 20:31:00 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 GRB250522.55 (trigger No 769611916,00h 11m 31.92s , +62d 43m 01.2s, R=22.13) errorbox 14609 sec after notice time and 14646 sec after trigger time at 2025-05-22 17:09:17 UT, with upper limit up to 17.3 mag. The observations began at zenith distance = 76 deg. The sun altitude is -18.5 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB250522.55 errorbox 38205 sec after notice time and 38241 sec after trigger time at 2025-05-22 23:42:32 UT, with upper limit up to 19.4 mag. The observations began at zenith distance = 64 deg. The sun altitude is -17.1 deg. The galactic latitude b = 0 deg., longitude l = 119 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2878290 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 14649 | 2025-05-22 17:09:17 | MASTER-Tunka | (02h 05m 46.41s , +50d 25m 27.7s) | C | 6 | 15.6 | 14728 | 2025-05-22 17:10:35 | MASTER-Tunka | (00h 05m 25.37s , +43d 01m 08.1s) | C | 6 | 13.3 | 15462 | 2025-05-22 17:22:50 | MASTER-Tunka | (00h 13m 45.70s , +53d 52m 42.5s) | C | 6 | 16.3 | 16126 | 2025-05-22 17:33:54 | MASTER-Tunka | (00h 42m 26.97s , +70d 56m 56.4s) | C | 6 | 16.9 | 16151 | 2025-05-22 17:34:18 | MASTER-Tunka | (23h 20m 09.37s , +62d 13m 49.0s) | C | 6 | 16.7 | 16175 | 2025-05-22 17:34:42 | MASTER-Tunka | (22h 25m 24.81s , +52d 48m 43.4s) | C | 6 | 16.2 | 16669 | 2025-05-22 17:42:57 | MASTER-Tunka | (22h 55m 39.92s , +83d 36m 50.1s) | C | 6 | 17.2 | 16693 | 2025-05-22 17:43:21 | MASTER-Tunka | (22h 02m 28.60s , +71d 56m 01.9s) | C | 6 | 17.3 | 16718 | 2025-05-22 17:43:46 | MASTER-Tunka | (21h 26m 18.01s , +60d 32m 24.2s) | C | 6 | 17.3 | 21581 | 2025-05-22 19:04:06 | MASTER-Tunka | (00h 42m 07.07s , +41d 08m 07.5s) | C | 90 | 14.5 | 21581 | 2025-05-22 19:04:06 | MASTER- | (00h 41m 41.55s , +41d 04m 52.5s) | C | 90 | 14.4 | 38332 | 2025-05-22 23:42:32 | MASTER-Kislovodsk | (00h 41m 39.16s , +41d 22m 03.8s) | C | 180 | 19.0 | 38512 | 2025-05-22 23:42:32 | MASTER-Kislovodsk | (00h 41m 39.16s , +41d 22m 04.0s) | C | 540 | 19.4 | Coadd 38533 | 2025-05-22 23:45:53 | MASTER-Kislovodsk | (00h 41m 32.32s , +41d 21m 36.5s) | C | 180 | 18.8 | 38735 | 2025-05-22 23:49:16 | MASTER-Kislovodsk | (00h 41m 32.44s , +41d 22m 40.1s) | C | 180 | 18.8 | 112734 | 2025-05-23 20:23:35 | MASTER-Kislovodsk | (03h 02m 54.34s , +56d 12m 15.7s) | C | 60 | 17.1 | 112817 | 2025-05-23 20:24:58 | MASTER-Kislovodsk | (03h 17m 09.58s , +56d 11m 13.2s) | C | 60 | 17.1 | 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/40543. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38574] EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40542 SUBJECT: EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability DATE: 25/05/23 19:51:55 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK <amitkundu515(a)gmail.com> D. O'Neill, A. Kumar, K. Ulaczyk, B. P. Gompertz, G. Ramsay, S. Moran, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report on behalf of the GOTO collaboration: We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al., 2022; Dyer et al., 2024) in response to the EP/WXT alert EP-WXT 01709176712 (Yang et al., GCN 40537). Targeted observations were performed beginning at 2025-05-23 12:56:35 UT (+0.2h post trigger) and continued through to 2025-05-23 15:17:24 UT (+2.55h post trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. We identify the stellar source reported by Yang et al., GCN 40537. Pre-trigger photometry from the GOTO archive shows the source exhibiting variability in the order of ±0.3 mag over the last 30 days. The latest pre-trigger photometry taken at 2025-05-22 21:44:20 UT (-15.0 h) has L = 15.38 ± 0.01 mag. Post trigger, the star rises to a peak L = 13.09 ± 0.01 mag at 2025-05-23 12:56:35 UT (+0.20 h) before fading to 14.29 ± 0.01 mag at 2025-05-23 15:17:24 UT (+2.55 h). Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. Reported magnitudes are in the AB system. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/40542. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38573] GRB 250521A: GRBAlpha detection
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40541 SUBJECT: GRB 250521A: GRBAlpha detection DATE: 25/05/23 18:31:11 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, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, M. Kolar, L. Szakszonova, 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 250521A (Fermi/GBM detection: GCN 40508) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract). The detection was confirmed at the peak time 2025-05-21 04:27:02.6 UTC. The T90 duration measured by GRBAlpha is 21 s and the overall significance during T90 reaches 8.6 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB250521A_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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40541. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38572] GRB 250520A: GRBAlpha detection
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40540 SUBJECT: GRB 250520A: GRBAlpha detection DATE: 25/05/23 18:30:23 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, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, M. Kolar, L. Szakszonova, 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 short-duration GRB 250520A (Swift/BAT detection: GCN 40491; SVOM/GRM detection: GCN 40495; AstroSat/CZTI detection: GCN 40497; Wind/Konus detection: GCN 40512, CALET/CGBM detection: GCN 40519) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract). The detection was confirmed at the peak time 2025-05-20 02:42:16.5 UTC. The T90 duration measured by GRBAlpha is 0.5 s and the overall significance during T90 reaches 11 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB250520A_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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40540. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38571] GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40539 SUBJECT: GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602) DATE: 25/05/23 14:53:57 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 769703188 at 14:26:23 on 23 May 2025 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 is: RA(2000.0) = 64.4 deg Decl.(2000.0) = 53.7 deg The 1 sigma statistical error radius is 2.9 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB250523602/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB250523602/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB250523602/json View this GCN Circular online at https://gcn.nasa.gov/circulars/40539. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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