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

[vsnet-grb-info 38460] EP250511a: Einstein Probe detection of an X-ray transient
by GCN Circulars 11 May '25

11 May '25

TITLE: GCN CIRCULAR NUMBER: 40429 SUBJECT: EP250511a: Einstein Probe detection of an X-ray transient DATE: 25/05/11 12:09:26 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> T. Y. Lian (NAO, CAS), A. Li (BNU), Y. L. Wang (NAO, CAS; ICE, CSIC-IEEC), C. C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250511a. The transient triggered EP-WXT (ID: 01709175648) at 2025-05-11T07:59:59 (UTC). The WXT position of the source is R.A. = 202.096 deg, DEC = -2.725 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 202.1113 deg, DEC = -2.7023 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. 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/40429. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38459] EP250508a: Gemini NIR upper limits
by GCN Circulars 11 May '25

11 May '25

TITLE: GCN CIRCULAR NUMBER: 40428 SUBJECT: EP250508a: Gemini NIR upper limits DATE: 25/05/11 07:27:31 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> A. J. Levan (Radboud and Warwick), J. C. Rastinejad (Northwestern), A. Martin-Carrillo (UCD), J. A. Quirola-Vasquez (Radboud), F. E. Bauer (SSI and UTA), G. Corcoran (UCD), R. A. J. Eyles-Ferris (Leicester), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud), report on behalf of a larger collaboration: We observed the field of the fast X-ray transient EP250508a (Liang et al., GCN 40390; Zhao et al., GCN 40399) using the Gemini-South telescope equipped with the FLAMINGOS-2 near-infrared imager (program GS-2025A-FT-106, PI Bauer). Observations were started on 2025 May 9 at 02:08:01 UT (20.07 hr after the EP trigger), and we secured 9 and 4.8 min imaging in the J and Ks bands, respectively. The seeing was modest at ~1.7" in the J-band image. No source is detected at the coordinates of the optical afterglow reported by SVOM/VT (Xin et al., GCN 40402; Li et al., GCN 40412), down to 5-sigma limiting magnitudes: J > 22.9 (AB system, 20.28 hr after trigger); Ks > 22.2 (AB system, 22.58 hr after trigger). These upper limits were calibrated using nearby stars from the VISTA Hemisphere Survey (VHS) catalogue. We thank excellent support from the observing staff at Gemini, in particular Venu Kalari and Henrique Reggiani. View this GCN Circular online at https://gcn.nasa.gov/circulars/40428. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38458] GRB 250510B: Fermi GBM Observation
by GCN Circulars 11 May '25

11 May '25

TITLE: GCN CIRCULAR NUMBER: 40427 SUBJECT: GRB 250510B: Fermi GBM Observation DATE: 25/05/11 05:33:44 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> A. Holzmann Airasca (UniTrento and INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 06:41:54.06 UT on 10 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250510B (trigger 768552119/250510279). which was also detected by Swift/BAT-GUANO (S. Ronchini et al. 2025, GCN 40419). The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position. The angle from the Fermi LAT boresight is 103 degrees. The GBM light curve consists of main emission episode with a duration (T90) of about 35 s (50-300 keV). The time-averaged spectrum from T0+0.51 to T0+35.58 s is best fit by a Band function with Epeak = 147 +/- 15 keV, alpha = 0.71 +/- 0.38, and beta = -2.79 +/- 0.49. The event fluence (10-1000 keV) in this time interval is (4.79 +/- 0.32)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.01 s in the 10-1000 keV band is 2.44 +/- 0.22 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/" View this GCN Circular online at https://gcn.nasa.gov/circulars/40427. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38457] Fermi GRB 250510C: Global MASTER-Net observations report
by GCN Circulars 11 May '25

11 May '25

TITLE: GCN CIRCULAR NUMBER: 40426 SUBJECT: Fermi GRB 250510C: Global MASTER-Net observations report DATE: 25/05/11 01:32:21 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 250510C ( Fermi GBM team, GCN 40424) errorbox 2642 sec after notice time and 2680 sec after trigger time at 2025-05-10 22:57:20 UT, with upper limit up to 19.5 mag. Observations started at twilight. The observations began at zenith distance = 41 deg. The sun altitude is -14.5 deg. The galactic latitude b = 29 deg., longitude l = 212 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2867339 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 2700 | 2025-05-10 22:57:20 | MASTER-OAFA | (09h 07m 31.64s , +09d 29m 09.5s) | C | 40 | 17.4 | 2710 | 2025-05-10 22:57:20 | MASTER-OAFA | (08h 58m 15.88s , +09d 06m 34.4s) | C | 60 | 19.3 | 2778 | 2025-05-10 22:58:38 | MASTER-OAFA | (09h 05m 01.80s , +07d 33m 46.8s) | C | 40 | 17.7 | 2788 | 2025-05-10 22:58:38 | MASTER-OAFA | (08h 55m 48.52s , +07d 11m 15.2s) | C | 60 | 19.4 | 2857 | 2025-05-10 22:59:56 | MASTER-OAFA | (08h 47m 55.47s , +05d 41m 08.9s) | C | 40 | 17.5 | 2867 | 2025-05-10 22:59:57 | MASTER-OAFA | (08h 38m 44.26s , +05d 18m 40.5s) | C | 60 | 19.1 | 2940 | 2025-05-10 23:01:20 | MASTER-OAFA | (09h 03m 07.27s , +05d 40m 38.9s) | C | 40 | 17.5 | 2951 | 2025-05-10 23:01:20 | MASTER-OAFA | (08h 53m 55.86s , +05d 18m 11.4s) | C | 60 | 19.2 | 3020 | 2025-05-10 23:02:40 | MASTER-OAFA | (09h 20m 18.53s , +07d 35m 47.0s) | C | 40 | 17.6 | 3030 | 2025-05-10 23:02:40 | MASTER-OAFA | (09h 11m 04.97s , +07d 13m 14.9s) | C | 60 | 19.3 | 3100 | 2025-05-10 23:03:59 | MASTER-OAFA | (08h 46m 42.34s , +03d 46m 36.1s) | C | 40 | 17.5 | 3110 | 2025-05-10 23:04:00 | MASTER-OAFA | (08h 37m 32.42s , +03d 24m 11.6s) | C | 60 | 19.1 | 3179 | 2025-05-10 23:05:18 | MASTER-OAFA | (09h 22m 52.75s , +09d 27m 55.7s) | C | 40 | 17.7 | 3189 | 2025-05-10 23:05:19 | MASTER-OAFA | (09h 13m 36.67s , +09d 05m 18.5s) | C | 60 | 19.3 | 3258 | 2025-05-10 23:06:38 | MASTER-OAFA | (09h 01m 57.14s , +03d 45m 59.4s) | C | 40 | 17.5 | 3268 | 2025-05-10 23:06:38 | MASTER-OAFA | (08h 52m 46.93s , +03d 23m 35.1s) | C | 60 | 19.2 | 3337 | 2025-05-10 23:07:57 | MASTER-OAFA | (09h 07m 31.37s , +09d 29m 55.9s) | C | 40 | 17.7 | 3347 | 2025-05-10 23:07:57 | MASTER-OAFA | (08h 58m 15.39s , +09d 07m 18.0s) | C | 60 | 19.4 | 3413 | 2025-05-10 23:09:13 | MASTER-OAFA | (09h 05m 01.60s , +07d 34m 02.9s) | C | 40 | 17.9 | 3424 | 2025-05-10 23:09:13 | MASTER-OAFA | (08h 55m 48.24s , +07d 11m 29.4s) | C | 60 | 19.4 | 3591 | 2025-05-10 23:12:10 | MASTER-OAFA | (08h 47m 50.34s , +05d 40m 45.5s) | C | 40 | 17.4 | 3601 | 2025-05-10 23:12:11 | MASTER-OAFA | (08h 38m 39.27s , +05d 18m 17.8s) | C | 60 | 19.0 | 3668 | 2025-05-10 23:13:28 | MASTER-OAFA | (09h 03m 06.64s , +05d 41m 53.6s) | C | 40 | 17.6 | 3678 | 2025-05-10 23:13:28 | MASTER-OAFA | (08h 53m 55.34s , +05d 19m 26.2s) | C | 60 | 19.3 | 3745 | 2025-05-10 23:14:45 | MASTER-OAFA | (09h 20m 24.61s , +07d 35m 03.9s) | C | 40 | 17.7 | 3756 | 2025-05-10 23:14:45 | MASTER-OAFA | (09h 11m 11.20s , +07d 12m 32.1s) | C | 60 | 19.3 | 3824 | 2025-05-10 23:16:03 | MASTER-OAFA | (08h 46m 35.12s , +03d 45m 49.5s) | C | 40 | 17.4 | 3834 | 2025-05-10 23:16:04 | MASTER-OAFA | (08h 37m 25.39s , +03d 23m 25.1s) | C | 60 | 19.1 | 3903 | 2025-05-10 23:17:22 | MASTER-OAFA | (09h 22m 58.02s , +09d 28m 41.5s) | C | 40 | 17.8 | 3913 | 2025-05-10 23:17:23 | MASTER-OAFA | (09h 13m 42.06s , +09d 06m 04.1s) | C | 60 | 19.4 | 3980 | 2025-05-10 23:18:40 | MASTER-OAFA | (09h 01m 52.76s , +03d 47m 45.9s) | C | 40 | 17.5 | 3991 | 2025-05-10 23:18:40 | MASTER-OAFA | (08h 52m 42.75s , +03d 25m 21.4s) | C | 60 | 19.3 | 4058 | 2025-05-10 23:19:57 | MASTER-OAFA | (09h 07m 30.76s , +09d 28m 27.1s) | C | 40 | 17.7 | 4068 | 2025-05-10 23:19:58 | MASTER-OAFA | (08h 58m 15.02s , +09d 05m 48.6s) | C | 60 | 19.5 | 4134 | 2025-05-10 23:21:13 | MASTER-OAFA | (09h 05m 04.47s , +07d 36m 06.6s) | C | 40 | 17.7 | 4144 | 2025-05-10 23:21:14 | MASTER-OAFA | (08h 55m 51.28s , +07d 13m 32.5s) | C | 60 | 19.4 | 4308 | 2025-05-10 23:24:07 | MASTER-OAFA | (08h 47m 48.67s , +05d 41m 58.8s) | C | 40 | 17.4 | 4318 | 2025-05-10 23:24:08 | MASTER-OAFA | (08h 38m 37.81s , +05d 19m 30.8s) | C | 60 | 18.9 | 4384 | 2025-05-10 23:25:24 | MASTER-OAFA | (09h 03m 10.75s , +05d 41m 08.5s) | C | 40 | 17.6 | 4394 | 2025-05-10 23:25:24 | MASTER-OAFA | (08h 53m 59.66s , +05d 18m 40.7s) | C | 60 | 19.1 | 4462 | 2025-05-10 23:26:42 | MASTER-OAFA | (09h 20m 16.31s , +07d 34m 20.1s) | C | 40 | 17.7 | 4473 | 2025-05-10 23:26:42 | MASTER-OAFA | (09h 11m 03.06s , +07d 11m 48.3s) | C | 60 | 19.2 | 4540 | 2025-05-10 23:28:00 | MASTER-OAFA | (08h 46m 41.42s , +03d 46m 01.9s) | C | 40 | 17.4 | 4551 | 2025-05-10 23:28:00 | MASTER-OAFA | (08h 37m 31.90s , +03d 23m 37.4s) | C | 60 | 19.0 | 4618 | 2025-05-10 23:29:18 | MASTER-OAFA | (09h 22m 54.00s , +09d 30m 22.2s) | C | 40 | 17.7 | 4628 | 2025-05-10 23:29:18 | MASTER-OAFA | (09h 13m 38.12s , +09d 07m 44.9s) | C | 60 | 19.3 | 4698 | 2025-05-10 23:30:38 | MASTER-OAFA | (09h 01m 52.32s , +03d 46m 19.6s) | C | 40 | 17.5 | 4708 | 2025-05-10 23:30:38 | MASTER-OAFA | (08h 52m 42.51s , +03d 23m 55.4s) | C | 60 | 19.1 | 4775 | 2025-05-10 23:31:55 | MASTER-OAFA | (09h 07m 33.62s , +09d 30m 04.9s) | C | 40 | 17.7 | 4785 | 2025-05-10 23:31:55 | MASTER-OAFA | (08h 58m 18.00s , +09d 07m 26.7s) | C | 60 | 19.4 | 4851 | 2025-05-10 23:33:11 | MASTER-OAFA | (09h 04m 57.09s , +07d 35m 27.3s) | C | 40 | 17.7 | 4862 | 2025-05-10 23:33:11 | MASTER-OAFA | (08h 55m 44.10s , +07d 12m 53.4s) | C | 60 | 19.3 | 4930 | 2025-05-10 23:34:30 | MASTER-OAFA | (08h 47m 54.19s , +05d 41m 14.7s) | C | 40 | 17.4 | 4941 | 2025-05-10 23:34:30 | MASTER-OAFA | (08h 38m 43.41s , +05d 18m 44.8s) | C | 60 | 19.0 | 5007 | 2025-05-10 23:35:46 | MASTER-OAFA | (09h 03m 05.73s , +05d 40m 24.1s) | C | 40 | 17.5 | 5017 | 2025-05-10 23:35:47 | MASTER-OAFA | (08h 53m 54.69s , +05d 17m 55.3s) | C | 60 | 19.1 | 5083 | 2025-05-10 23:37:03 | MASTER-OAFA | (09h 20m 23.31s , +07d 34m 43.4s) | C | 40 | 17.7 | 5094 | 2025-05-10 23:37:03 | MASTER-OAFA | (09h 11m 10.07s , +07d 12m 10.4s) | C | 60 | 19.1 | 5162 | 2025-05-10 23:38:22 | MASTER-OAFA | (08h 46m 38.03s , +03d 47m 57.1s) | C | 40 | 17.3 | 5173 | 2025-05-10 23:38:22 | MASTER-OAFA | (08h 37m 28.61s , +03d 25m 31.9s) | C | 60 | 18.9 | 5242 | 2025-05-10 23:39:41 | MASTER-OAFA | (09h 22m 53.54s , +09d 28m 45.0s) | C | 40 | 17.7 | 5252 | 2025-05-10 23:39:42 | MASTER-OAFA | (09h 13m 37.77s , +09d 06m 07.3s) | C | 60 | 19.3 | 5320 | 2025-05-10 23:41:00 | MASTER-OAFA | (09h 01m 54.38s , +03d 48m 23.7s) | C | 40 | 17.5 | 5330 | 2025-05-10 23:41:00 | MASTER-OAFA | (08h 52m 44.67s , +03d 25m 59.0s) | C | 60 | 19.0 | 5398 | 2025-05-10 23:42:17 | MASTER-OAFA | (09h 07m 27.75s , +09d 29m 44.3s) | C | 40 | 17.7 | 5408 | 2025-05-10 23:42:18 | MASTER-OAFA | (08h 58m 12.26s , +09d 07m 06.1s) | C | 60 | 19.3 | 5473 | 2025-05-10 23:43:33 | MASTER-OAFA | (09h 04m 56.34s , +07d 36m 39.5s) | C | 40 | 17.7 | 5484 | 2025-05-10 23:43:33 | MASTER-OAFA | (08h 55m 43.45s , +07d 14m 05.6s) | C | 60 | 19.2 | 5552 | 2025-05-10 23:44:51 | MASTER-OAFA | (08h 47m 49.09s , +05d 40m 24.5s) | C | 40 | 17.4 | 5562 | 2025-05-10 23:44:52 | MASTER-OAFA | (08h 38m 38.50s , +05d 17m 55.0s) | C | 60 | 18.9 | 5628 | 2025-05-10 23:46:08 | MASTER-OAFA | (09h 03m 11.45s , +05d 40m 56.4s) | C | 40 | 17.6 | 5639 | 2025-05-10 23:46:08 | MASTER-OAFA | (08h 54m 00.57s , +05d 18m 27.8s) | C | 60 | 19.1 | 5705 | 2025-05-10 23:47:25 | MASTER-OAFA | (09h 20m 19.52s , +07d 36m 39.8s) | C | 40 | 17.7 | 5715 | 2025-05-10 23:47:25 | MASTER-OAFA | (09h 11m 06.40s , +07d 14m 07.2s) | C | 60 | 19.3 | 5783 | 2025-05-10 23:48:43 | MASTER-OAFA | (08h 46m 37.72s , +03d 46m 50.6s) | C | 40 | 17.4 | 5794 | 2025-05-10 23:48:43 | MASTER-OAFA | (08h 37m 28.49s , +03d 24m 25.9s) | C | 60 | 18.9 | 5861 | 2025-05-10 23:50:01 | MASTER-OAFA | (09h 22m 56.76s , +09d 30m 53.4s) | C | 40 | 17.7 | 5872 | 2025-05-10 23:50:01 | MASTER-OAFA | (09h 13m 41.10s , +09d 08m 16.1s) | C | 60 | 19.3 | 5938 | 2025-05-10 23:51:18 | MASTER-OAFA | (09h 01m 47.87s , +03d 47m 35.9s) | C | 40 | 17.5 | 5948 | 2025-05-10 23:51:18 | MASTER-OAFA | (08h 52m 38.34s , +03d 25m 12.0s) | C | 60 | 19.1 | 6015 | 2025-05-10 23:52:35 | MASTER-OAFA | (09h 07m 26.39s , +09d 30m 55.0s) | C | 40 | 17.8 | 6025 | 2025-05-10 23:52:35 | MASTER-OAFA | (08h 58m 11.05s , +09d 08m 17.2s) | C | 60 | 19.2 | 6091 | 2025-05-10 23:53:51 | MASTER-OAFA | (09h 05m 02.19s , +07d 35m 49.1s) | C | 40 | 17.7 | 6101 | 2025-05-10 23:53:51 | MASTER-OAFA | (08h 55m 49.50s , +07d 13m 15.9s) | C | 60 | 19.2 | 6170 | 2025-05-10 23:55:09 | MASTER-OAFA | (08h 47m 54.28s , +05d 41m 01.5s) | C | 40 | 17.3 | 6180 | 2025-05-10 23:55:10 | MASTER-OAFA | (08h 38m 43.87s , +05d 18m 32.7s) | C | 60 | 18.8 | 6248 | 2025-05-10 23:56:27 | MASTER-OAFA | (09h 03m 07.31s , +05d 42m 40.8s) | C | 40 | 17.5 | 6258 | 2025-05-10 23:56:28 | MASTER-OAFA | (08h 53m 56.59s , +05d 20m 12.5s) | C | 60 | 19.0 | 6324 | 2025-05-10 23:57:44 | MASTER-OAFA | (09h 20m 19.06s , +07d 35m 12.4s) | C | 40 | 17.6 | 6335 | 2025-05-10 23:57:44 | MASTER-OAFA | (09h 11m 06.13s , +07d 12m 40.5s) | C | 60 | 19.1 | 6404 | 2025-05-10 23:59:04 | MASTER-OAFA | (08h 46m 40.91s , +03d 48m 01.2s) | C | 40 | 17.2 | 6414 | 2025-05-10 23:59:04 | MASTER-OAFA | (08h 37m 31.88s , +03d 25m 36.7s) | C | 60 | 18.8 | 6483 | 2025-05-11 00:00:22 | MASTER-OAFA | (09h 22m 49.32s , +09d 30m 08.6s) | C | 40 | 17.6 | 6493 | 2025-05-11 00:00:23 | MASTER-OAFA | (09h 13m 33.80s , +09d 07m 31.7s) | C | 60 | 19.2 | 6565 | 2025-05-11 00:01:45 | MASTER-OAFA | (09h 01m 48.71s , +03d 48m 44.6s) | C | 40 | 17.5 | 6575 | 2025-05-11 00:01:45 | MASTER-OAFA | (08h 52m 39.36s , +03d 26m 20.8s) | C | 60 | 19.0 | 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/40426. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38456] Fermi GRB 250510B: Global MASTER-Net observations report
by GCN Circulars 11 May '25

11 May '25

TITLE: GCN CIRCULAR NUMBER: 40425 SUBJECT: Fermi GRB 250510B: Global MASTER-Net observations report DATE: 25/05/11 01:31:12 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 250510B ( Fermi GBM team, GCN 40418) errorbox 62438 sec after notice time and 62477 sec after trigger time at 2025-05-11 00:03:11 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 27 deg. The sun altitude is -28.5 deg. The galactic latitude b = 9 deg., longitude l = 250 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2866812 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 62497 | 2025-05-11 00:03:11 | MASTER-OAFA | (08h 43m 33.97s , -26d 38m 01.3s) | C | 40 | 17.5 | 62508 | 2025-05-11 00:03:11 | MASTER-OAFA | (08h 33m 17.64s , -26d 59m 17.6s) | C | 60 | 18.8 | 62575 | 2025-05-11 00:04:28 | MASTER-OAFA | (08h 51m 56.95s , -24d 43m 41.9s) | C | 40 | 17.6 | 62585 | 2025-05-11 00:04:29 | MASTER-OAFA | (08h 41m 50.32s , -25d 05m 00.8s) | C | 60 | 19.0 | 62653 | 2025-05-11 00:05:47 | MASTER-OAFA | (08h 35m 04.55s , -24d 42m 42.7s) | C | 40 | 17.6 | 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/40425. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38455] GRB 250510C: Fermi GBM Final Real-time Localization
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40424 SUBJECT: GRB 250510C: Fermi GBM Final Real-time Localization DATE: 25/05/10 22:23:13 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 SHORT GRB At 22:12:40 UT on 10 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250510C (trigger 768607965.139286 / 250510925). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 127.9, Dec = 13.4 (J2000 degrees, equivalent to J2000 08h 31m, 13d 24'), with a statistical uncertainty of 12.8 degrees. The angle from the Fermi LAT boresight is 15.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250510925/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250510925/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250510925/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40424. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38454] GRB 250510A: Swift-XRT observations
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40423 SUBJECT: GRB 250510A: Swift-XRT observations DATE: 25/05/10 16:54:51 GMT FROM: Simone Dichiara at Pennsylvania State University <sbd5667(a)psu.edu> S. Dichiara (PSU), K.L. Page (U. Leicester), J.A. Kennea (PSU), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. A. Williams (PSU), J.P. Osborne (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 1.8 ks of XRT data for GRB 250510A, from 10.2 ks to 20.8 ks after the SVOM/ECLAIRs trigger. The data are entirely in Photon Counting (PC) mode. Within the SVOM/ECLAIRs 90% C.L. error region (GCN #40415) we detect the EP-FXT source EPF_J185624.8+181937 (GCN#40420) at RA, Dec = 284.10364, +18.3267 which is equivalent to: RA (J2000): 18h 56m 24.87s Dec (J2000): +18d 19′ 36.0″ with an uncertainty of 5.7 arcsec (radius, 90% confidence). The source has a mean count rate of 7.3e-03 ct/sec and a flux of 3.2 (+1.3, -1.1) × 10^-13 erg cm^-2 s^-1 (0.3-10 keV); we note that this position is also consistent with a known 2MASS source, 2MASS J18562485+1819380. No other X-ray sources have been detected. The 3-sigma upper limit in the field ranges from ~4.4e-03 to ~1.0e-02 ct s^-1, corresponding to a 0.3-10 keV observed flux of 1.9e-13 to 4.4e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum). The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00016/. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40423. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38453] GRB 250509A: Fermi GBM Observation
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40422 SUBJECT: GRB 250509A: Fermi GBM Observation DATE: 25/05/10 16:51:18 GMT FROM: Ava Myers at NASA GSFC <ava.myers(a)nasa.gov> A. Myers (NPP/GSFC), C. Meegan (UAH) and A. Holzmann Airasca (UniTrento and INFN Bari) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 22:33:29.29 UT on 09 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250509A (trigger 768522814/250509940). which was also detected by Swift BAT (M. H. Siegel et al. 2025, GCN 40407). The Fermi GBM on-ground location is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 89 degrees. The GBM light curve consists of main emission episode with a duration (T90) of about 69 s (50-300 keV). The time-averaged spectrum from T0+0.000 to T0+69.120 s is best fit by a power law function. The power law index is -2.19 +/- 0.03. The event fluence (10-1000 keV) in this time interval is (6.18 +/- 0.29)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+6.2 s in the 10-1000 keV band is 3.6 +/- 0.3 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: View this GCN Circular online at https://gcn.nasa.gov/circulars/40422. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38452] IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40421 SUBJECT: IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility DATE: 25/05/10 16:32:23 GMT FROM: Robert David Stein at JSI <rdstein(a)umd.edu> Akshay Eranhalodi (DESY), Robert Stein (JSI), Jannis Necker (DESY), Anna Franckowiak (Ruhr University Bochum) and Jesper Sollerman (Stockholm) report: On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: As part of the ZTF neutrino follow up program (Stein et al. 2023), we observed the localization region of the neutrino event IceCube-250506A (Zegarelli et. al, GCN 40369) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-05-08 04:24 UTC, approximately 38.2 hours after event time. Observations were delayed due to poor weather. We covered 78.5% (0.7 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019). We are left with the following high-significance candidate, lying within the 90.0% localization of the skymap. +--------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr | +--------------------------------------------------------------------------------+ | ZTF23aabbszx | AT2023fyh | 116.1542766 | +35.3663416 | r | 19.29 | 0.17 | +--------------------------------------------------------------------------------+ ZTF23aabbszx is a nuclear source, and was first detected on 2023-01-25. It has a spectrum in DESI, with a redshift of z=0.3860 and clear AGN signatures. It similarly has AGN-like WISE colours of W1-W2=0.76. Based on this, we conclude that ZTF23aabbszx is an AGN. The source has been undergoing a long period of outburst, beginnning more than 800 days ago, with at least two distinct flares. The most recent flare began 300 days ago, and the source has been fading for the past 50 days. There is no particular activity in the past 6 months which suggest a connection to the high-energy neutrino. Observations of this field will continue as part of our standard ToO cadence for high-energy neutrinos (Stein et al. 2023). Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan; Operations are conducted by Caltech's Optical Observatory (COO), Caltech/IPAC, and the University of Washington at Seattle, USA. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). Alert filtering is performed with the nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ). View this GCN Circular online at https://gcn.nasa.gov/circulars/40421. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38451] GRB 250510A: follow-up observation with EP-FXT
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40420 SUBJECT: GRB 250510A: follow-up observation with EP-FXT DATE: 25/05/10 15:12:36 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> A. Li, B. B. Zhang (BNU), Q. C. Liu (THU), Z. X. Ling (NAOC, CAS) on behalf of the Einstein Probe (EP) team: Following the possible detection of the GRB 250510A (Cheng et al., GCN 40415) and its multi-wavelength follow-up observations (Antier et al., GCN 40417), we performed an observation with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe mission. The observations began at 2025-05-10T07:54:01 (UTC), about 3.3 hours after the SVOM-ECLAIRs detection. The exposure time is 4035 seconds. Preliminary analysis shows there are three source was detected in this epoch within the ECLAIRs error circle: ------------------------------------------------------------------------------------------------------ | Source Name | RA | DEC | Flux(erg/s/cm2) | Flux_err | ------------------------------------------------------------------------------------------------------ |EPF_J185647.0+182414| 284.1957 | 18.4041 | 9.91e-14 | 3.41e-14 | ------------------------------------------------------------------------------------------------------ |EPF_J185624.3+182129| 284.1012 | 18.3581 | 1.07e-13 | 2.59e-14 | ------------------------------------------------------------------------------------------------------ |EPF_J185624.8+181937| 284.1033 | 18.3269 | 1.35e-13 | 2.92e-14 | ------------------------------------------------------------------------------------------------------ EP-FXT will continue monitoring the source. More follow-up observations are encouraged. 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/40420. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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