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

[vsnet-grb-info 40912] GRB 251126A: Swift detection of a burst
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42843 SUBJECT: GRB 251126A: Swift detection of a burst DATE: 25/11/26 19:26:44 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> R. Caputo (GSFC), M. J. Moss (GSFC), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 19:10:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 251126A (trigger=1417793). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 99.910, +54.987 which is RA(J2000) = 06h 39m 39s Dec(J2000) = +54d 59' 13" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~2600 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 19:11:58.3 UT, 81.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 99.94124, 54.98591 which is equivalent to: RA(J2000) = 06h 39m 45.90s Dec(J2000) = +54d 59' 09.3" with an uncertainty of 4.4 arcseconds (radius, 90% containment). This location is 64 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. No spectrum from the promptly downlinked event data is yet available to determine the column density. There are no UVOT data available at this time. Analysis will be reported at a later time. Burst Advocate for this burst is R. Caputo (regina.caputo AT nasa.gov) Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42843. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40911] GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42842 SUBJECT: GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3 DATE: 25/11/26 16:30:16 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Jean-Grégoire Ducoin (CPPM), Noémie Globus (UNAM), N. A. Rakotondrainibe (LAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We reobserved the field of the MASTER OT J155558.56+581224.1 candidate afterglow (Gress et al., GCN Circ. 42838) of the Fermi GRB 251125B (Fermi GBM team., GCN Circ. 42836) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-11-26 11:44 to 13:00 UTC (from 15.34 to 16.60 hours after the trigger) and obtained 20 minutes of exposure in each of the g, r, and i filters and 60 minutes of simultaneous exposure in the z filter. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. Compared to our first epoch of observations (Globus et al., GCN Circ. 42840), the afterglow has continued to fade. After correcting for the Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.013 mag (Schlafly & Finkbeiner 2011) and fitting a power-law with a no-dust extinction model to the griz-bands, we estimate a photometric redshift upper limit of z < 3. We therefore encourage follow-up observations. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42842. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40910] EP251124b follow-up observation by EP-FXT
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42841 SUBJECT: EP251124b follow-up observation by EP-FXT DATE: 25/11/26 10:26:21 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> B. Zhang, J. P. Feng (USTC), D. F. Hu (PMO, CAS), H. Sun, H. N. Yang (NAO, CAS), Z. C. Zou (NJU) on behalf of the Einstein Probe (EP) team: We performed a Target-of-Opportunity observation with the Follow-up X-ray Telescope on board the Einstein Probe (EP) for EP251124b (Feng et al, GCN 42834), which was also followed by Lipunov et al. (GCN #42835) and van Hoof et al. (GCN #42839). The observation began at 2025-11-25T22:12:00 (UTC) with an exposure time of about 1790 seconds. An uncatalogued X-ray source was detected within the WXT error circle at R.A. = 93.4802 deg, DEC = 52.7313 deg (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. including both statistical and systematic uncertainties). The average FXT 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.5 x 10^21 cm^-2 and a photon index of 0.97 (-0.84, +0.93). The derived average unabsorbed 0.5-10 keV flux is 9.02 (-5.33, +13.9) x 10^(-13) erg/s/cm^2. 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/42841. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40909] GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42840 SUBJECT: GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate DATE: 25/11/26 05:51:53 GMT FROM: globus(a)astro.unam.mx Noémie Globus (UNAM), Jean-Grégoire Ducoin (CPPM), Alan M. Watson (UNAM), Nathaniel R. Butler (ASU), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Camila Angulo (UNAM), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the MASTER OT J155558.56+581224.1 candidate afterglow (Gress et al., GCN Circ. 42838) of the Fermi GRB 251125B (Fermi GBM team., GCN Circ. 42836) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-11-26 01:36 to 02:39 UTC (median epoch 5.73 hours after the trigger) and obtained 48 minutes of simultaneous exposure in each of the r and z filters. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detect the optical candidate at preliminary magnitudes of: r = 20.46 +/- 0.02 z = 20.17 +/- 0.05 The source has faded considerably since the observation of Gress et al. (GCN Circ 42838), which confirms that it is likely to be the afterglow of the GRB. Further observations are planned. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42840. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40908] EP251124b: NOT r- and z-band optical upper limits
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42839 SUBJECT: EP251124b: NOT r- and z-band optical upper limits DATE: 25/11/26 00:24:55 GMT FROM: Agnes van Hoof at Radboud University <agnes.vanhoof(a)ru.nl> A. P. C. van Hoof (Radboud), G. Corcoran (UCD), J. N. D. van Dalen, A. Martin-Carrillo (UCD), D. Xu (NAOC), S.Q. Jiang (NAO, CAS), T. Pursimo (NOT, Aarhus University), J.P.U. Fynbo (DAWN/NBI), P. G. Jonker (Radboud) report on behalf of a larger collaboration: We observed the field of the fast X-ray transient EP251124b (Feng et al., GCN 42834) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were obtained in the r (3x300 s) and z (5x200 s) bands, starting on 2025-11-25 at 22:19:58.38 UTC (1.2 days after the WXT trigger). No new source is detected within the EP/WXT uncertainty region (Feng et al., GCN 42834). From the stacked images we obtain the following 3-sigma upper limits: r > 24.4 z > 23.2 These upper limits are in AB magnitudes and were calibrated using nearby stars from the Pan-STARRS catalog and are not corrected for Galactic extinction. We also performed image subtraction in r band using a reference image from the Legacy Survey. No new source is revealed compared to the reference. However, we note that there are artefacts across the field. View this GCN Circular online at https://gcn.nasa.gov/circulars/42839. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40907] Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
by GCN Circulars 25 Nov '25

25 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42838 SUBJECT: Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery DATE: 25/11/25 23:04:15 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> O.A.Gress, N.M.Budnev (Irkutsk State University), V.M. Lipunov, A.Kuznetsov, I.Panchenko, E.Gorbovskoy, G.Antipov, P.Balanutsa, V.Senik, I.Panchenko, N. Tiurina, K.Zhirkov, Ya.Kechin, A.Chasovnikov, V.Topolev, D.Vlasenko, Yu. Tselik(Lomonosov MSU, SAI, Moscow), R. Podesta, C.Francile, F. Podesta, E. Gonzalez (OAFA, San Juan Uni.,Argentina); D. Buckley (SAAO, South Africa), O.Ershova (Irkutsk State University), A. Sosnovskij (CrAO RAS), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias,Spain), MASTER-Tunka robotic telescope (Global MASTER-Net [1-4], http://observ.pereplet.ru) started inspect (Lipunov et al. GCN 42837) of Fermi GRB 251125B ( GCN 42836) at MASTER-Tunka and MASTER-Kislovodsk. MASTER auto-detection system discovered optical counterpart of this GRB MASTER OT J155558.56+581224.1 with unfiltered m_OT=18.2 at 2025-11-25 20:34:32UT with typical for GRB light curve with decay. https://www.wis-tns.org/object/2025aevl Real time updated cover map and discovered OT position is available here: https://master.sai.msu.ru/site/master2/observ.php?id=3051835 Observations and data analysis will be continued. [1] Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L [2] Lipunov et al. 2022, Universe, Vol. 8(5), id.271 [3] Lipunov et a. 2019, ARep, vol.63, 293 [4] Lipunov V., Kornilov V., Gorbovskoy E., Tiurina N., Kuznetsov A. 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics,Lomonosov MSU PRESS, 591pp. http://www.pereplet.ru/lipunov/625.html#625 View this GCN Circular online at https://gcn.nasa.gov/circulars/42838. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40906] Fermi GRB 251125B: Global MASTER-Net observations report
by GCN Circulars 25 Nov '25

25 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42837 SUBJECT: Fermi GRB 251125B: Global MASTER-Net observations report DATE: 25/11/25 20:45:36 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 [1] located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 251125B ( Fermi GBM team, GCN 42836) errorbox 37 sec after notice time and 71 sec after trigger time at 2025-11-25 20:24:57 UT, with upper limit up to 19.8 mag. The observations began at zenith distance = 62 deg. The sun altitude is -39.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251125B errorbox 40 sec after notice time and 74 sec after trigger time at 2025-11-25 20:25:00 UT, with upper limit up to 13.2 mag. The observations began at zenith distance = 79 deg. The sun altitude is -66.8 deg. The galactic latitude b = 46 deg., longitude l = 89 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3051835 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 76 | 2025-11-25 20:24:57 | MASTER-Tunka | (15h 49m 53.68s , +58d 02m 46.1s) | C | 10 | 19.0 | 77 | 2025-11-25 20:24:57 | MASTER- | (15h 50m 33.82s , +57d 56m 14.3s) | C | 10 | 18.9 | 80 | 2025-11-25 20:25:00 | MASTER-Kislovodsk | (15h 48m 55.38s , +57d 57m 14.7s) | C | 10 | 12.3 | 81 | 2025-11-25 20:25:01 | MASTER-Kislovodsk | (15h 41m 25.24s , +58d 17m 41.9s) | C | 10 | 12.3 | 613 | 2025-11-25 20:33:29 | MASTER-Tunka | (15h 50m 14.31s , +57d 20m 48.8s) | C | 60 | 19.0 | 673 | 2025-11-25 20:33:29 | MASTER-Tunka | (15h 50m 14.31s , +57d 20m 48.8s) | C | 180 | 19.8 | Coadd 613 | 2025-11-25 20:33:29 | MASTER- | (15h 50m 55.15s , +57d 14m 04.0s) | C | 60 | 18.9 | 649 | 2025-11-25 20:33:35 | MASTER-Kislovodsk | (15h 49m 05.73s , +57d 13m 41.7s) | C | 120 | 12.9 | 677 | 2025-11-25 20:34:32 | MASTER-Tunka | (15h 50m 14.11s , +57d 20m 48.0s) | C | 60 | 19.2 | 677 | 2025-11-25 20:34:32 | MASTER- | (15h 50m 55.07s , +57d 14m 02.7s) | C | 60 | 19.1 | 740 | 2025-11-25 20:35:36 | MASTER-Tunka | (15h 50m 13.87s , +57d 20m 46.9s) | C | 60 | 18.9 | 740 | 2025-11-25 20:35:36 | MASTER- | (15h 50m 54.92s , +57d 14m 02.1s) | C | 60 | 18.7 | 789 | 2025-11-25 20:35:54 | MASTER-Kislovodsk | (15h 49m 06.58s , +57d 13m 30.8s) | C | 120 | 13.2 | 803 | 2025-11-25 20:36:39 | MASTER-Tunka | (15h 50m 13.66s , +57d 20m 45.9s) | C | 60 | 19.5 | 804 | 2025-11-25 20:36:39 | MASTER- | (15h 50m 54.78s , +57d 14m 01.8s) | C | 60 | 19.3 | 928 | 2025-11-25 20:38:14 | MASTER-Kislovodsk | (15h 49m 07.46s , +57d 13m 23.9s) | C | 120 | 13.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42837. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40905] GRB 251125B: Fermi GBM Final Real-time Localization
by GCN Circulars 25 Nov '25

25 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42836 SUBJECT: GRB 251125B: Fermi GBM Final Real-time Localization DATE: 25/11/25 20:34:30 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 20:23:45 UT on 25 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251125B (trigger 785795030.880336 / 251125850). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 237.5, Dec = 57.5 (J2000 degrees, equivalent to J2000 15h 50m, 57d 30'), with a statistical uncertainty of 3.1 degrees. The angle from the Fermi LAT boresight is 45.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251125850/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251125850/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251125850/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42836. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40904] EP251124b: Global MASTER-Net observations report
by GCN Circulars 25 Nov '25

25 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42835 SUBJECT: EP251124b: Global MASTER-Net observations report DATE: 25/11/25 15:54:29 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 [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP251124b ( EP Team et al., GCN 42834) errorbox 186 sec after notice time and 80214 sec after trigger time at 2025-11-25 15:39:56 UT, with upper limit up to 15.3 mag. The observations began at zenith distance = 68 deg. The sun altitude is -21.6 deg. The galactic latitude b = 17 deg., longitude l = 162 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3051627 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 80245 | 2025-11-25 15:39:56 | MASTER-Kislovodsk | (06h 13m 18.49s , +52d 39m 59.0s) | C | 60 | 15.3 | 80245 | 2025-11-25 15:39:56 | MASTER-Kislovodsk | (06h 13m 25.72s , +52d 17m 24.8s) | C | 60 | 13.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42835. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40903] EP251124b: EP-WXT detection of a fast X-ray transient
by GCN Circulars 25 Nov '25

25 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42834 SUBJECT: EP251124b: EP-WXT detection of a fast X-ray transient DATE: 25/11/25 15:33:27 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. P. Feng, B. Zhang (USTC), X. X. Sun (NAO, CAS), Q. C. Liu (THU), D. F. Hu, Y. L. Hua (PMO, CAS), C. C. Jin (NAO, CAS), on behalf of the Einstein Probe (EP) team: We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP251124b. The transient was detected by EP-WXT at 2025-11-24T17:23:02 (UTC). The WXT position of the source is R.A. = 93.493 deg, DEC = 52.694 deg (J2000) with an uncertainty of 2.6 arcmin in radius (90% C.L. statistical and systematic). The transient event lasts for ～240 seconds, the average 0.5-4 keV spectrum can be fitted with an absorbed power-law model, with fixed galactic nH of 1.51 x 10^21 cm^-2 and a photon index of 1.72 (-0.78, +0.83). The unabsorbed average 0.5-4 keV flux is estimated to be 2.97 (-0.95, +1.51) x 10^-10 erg/s/cm2. The peak flux reaches around 4.8e-9 erg/s/cm2. The uncertainties are at the 90% confidence level for the above parameters. The transient was discovered by the ground analysis of the delayed telemetry data. The follow-up observation of EP-FXT has been scheduled. 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/42834. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0