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

[vsnet-grb-info 39863] GRB 250909B: Insight-HXMT detection
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41797 SUBJECT: GRB 250909B: Insight-HXMT detection DATE: 25/09/11 15:16:08 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-09-09T17:49:10.200 (T0), Insight-HXMT/HE detected the burst GRB 250909B, which is also detected by AstroSat (M. Tembhurnikar et al., GCN#41775), SVOM/GRM (Wang et al., GCN#41796) and Konus-Wind. The Insight-HXMT/HE light curve mainly consists of multi-pulses with a T90 of 12.9 +1.2/-1.7 s. The 1s peak rate, measured from T0+0.250 s, is 5422 cnts/sec. The total counts from this burst is 23044 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb250909B.png All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org. View this GCN Circular online at https://gcn.nasa.gov/circulars/41797. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39862] GRB 250909B: SVOM/GRM observation
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41796 SUBJECT: GRB 250909B: SVOM/GRM observation DATE: 25/09/11 15:07:29 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: Jean-Luc Atteia (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by GRB 250909B at 2025-09-09T17:49:10.200 UTC (T0), which is also detected by AstroSat (M. Tembhurnikar et al., GCN#41775) and Konus-Wind. With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a multi-pulses with a T90 of 10.5 +3.5/-1.5 s in the 15-5000 keV band. ECLAIRs was not collecting data at the time of this burst. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250909B.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/41796. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39861] LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41795 SUBJECT: LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification DATE: 25/09/11 13:17:25 GMT FROM: natalie.williams(a)uni-potsdam.de The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S250911ac (GCN Circular 41786). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250911ac %}Assuming the candidate is astrophysical, the updated classification of the GW signal, in order of descending probability, is BBH (96%), Terrestrial (4%), BNS (<1%), or NSBH (<1%). For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 952 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1124 +/- 285 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41795. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39860] GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41794 SUBJECT: GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery DATE: 25/09/11 12:51:17 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> B. Schneider (LAM), A. Martin-Carrillo (UCD), M. Garnichey (LUX-Paris Obs.), V. D'Elia (ASI-SSDC), A. J. Levan (Radboud U.), G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. Saccardi (CEA/Irfu), A. L. Thakur (INAF-IAPS), S. D. Vergani (LUX-Paris Obs.) report on behalf of the Stargate collaboration: We observed again the field of GRB 250910A / EP250910a (Ma et al., GCN 41769; Götz et al. GCN 41770; Wu et al., GCN 41772; Li et al., GCN 41774; Liu et al., GCN 41776) using the ESO VLT UT4 (Yepun) equipped with the HAWK-I NIR camera. We obtained 15 min imaging in the J band, beginning on 2025-09-11 at 09:36:48 UT (1.26 days post-trigger). Carrying out image subtraction with HOTPANTS between our new and previous (Garnichey et al., GCN 41777) images, a clear transient source is detected at coordinates (0.5" error): RA(J2000) = 02:39:12.56 Dec(J2000) = -39:41:40.9 These coordinates are consistent with the EP/FXT X-ray location (Liu et al., GCN 41776) and Swift/XRT X-ray detection (https://www.swift.ac.uk/SVOM/SVOM_FIELD00036/) We measure for the transient a magnitude J = 22.73 +/- 0.08 (AB, at 5.2 hr post trigger), calibrated against nearby 2MASS stars and not corrected for Galactic extinction. We caution that strictly this is a lower limit to the source brightness, as it is possible that residual transient light was present in our second observation. The spatial association with the X-ray afterglow and its fading behavior indicate that this object is the NIR afterglow of GRB 250910A / EP250910a. We note that at this location, an extended optical source can be seen in the Legacy Survey (magnitudes g = 24.56, r = 23.80, i = 23.38, z = 23.66), likely being the host galaxy of this source. We acknowledge excellent support from the ESO observing staff in Paranal, in particular Juan Carlos Olivares and Robert De Rosa. View this GCN Circular online at https://gcn.nasa.gov/circulars/41794. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39859] EP250911a: COLIBRÍ optical observations
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41793 SUBJECT: EP250911a: COLIBRÍ optical observations DATE: 25/09/11 12:10:52 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Camila Angulo (UNAM), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Dalya Akl (NYUAD), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the EP250711a (Liang et al., GCN Circ. 41788) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-11-09 09:29 to 10:33 UTC (from 0.52 to 1.58 hours after the trigger, and 13 minutes after the notice) and obtained 45 minutes of exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. In our both filters, we detected the optical counterpart reported by LCO (Quirola-Vasquez et al., GCN Circ. 41790), at preliminary magnitudes of: r = 20.57 +/- 0.02 z = 19.87 +/- 0.03 Further observations and analysis are ongoing. 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/41793. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39858] LIGO/Virgo/KAGRA S250908y: Updated Sky localization
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41792 SUBJECT: LIGO/Virgo/KAGRA S250908y: Updated Sky localization DATE: 25/09/11 11:27:49 GMT FROM: natalie.williams(a)uni-potsdam.de The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250908y (GCN Circular 41750). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250908y For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 9926 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1146 +/- 334 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41792. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39857] Fermi GRB 250910B: Global MASTER-Net observations report
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41791 SUBJECT: Fermi GRB 250910B: Global MASTER-Net observations report DATE: 25/09/11 10:31:00 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-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 250910B ( Fermi GBM team, GCN 41778) errorbox 45057 sec after notice time and 45097 sec after trigger time at 2025-09-11 07:23:42 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 40 deg. The sun altitude is -41.7 deg. The galactic latitude b = -34 deg., longitude l = 252 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2989479 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 45128 | 2025-09-11 07:23:42 | MASTER-OAFA | (05h 21m 01.46s , -46d 16m 04.7s) | C | 60 | 19.9 | 45203 | 2025-09-11 07:24:58 | MASTER-OAFA | (05h 21m 06.25s , -46d 17m 02.2s) | C | 60 | 19.8 | 45277 | 2025-09-11 07:26:12 | MASTER-OAFA | (05h 21m 01.18s , -46d 17m 59.3s) | C | 60 | 19.9 | 45353 | 2025-09-11 07:27:28 | MASTER-OAFA | (05h 21m 05.78s , -46d 17m 54.0s) | C | 60 | 19.9 | 45428 | 2025-09-11 07:28:43 | MASTER-OAFA | (05h 21m 03.82s , -46d 16m 02.0s) | C | 60 | 19.8 | 45503 | 2025-09-11 07:29:58 | MASTER-OAFA | (05h 21m 03.84s , -46d 17m 30.1s) | C | 60 | 19.8 | 45579 | 2025-09-11 07:31:13 | MASTER-OAFA | (05h 21m 06.46s , -46d 16m 12.8s) | C | 60 | 19.8 | 45656 | 2025-09-11 07:32:31 | MASTER-OAFA | (05h 21m 00.95s , -46d 16m 45.4s) | C | 60 | 19.8 | 45734 | 2025-09-11 07:33:49 | MASTER-OAFA | (05h 21m 01.87s , -46d 15m 42.5s) | C | 60 | 19.8 | 45811 | 2025-09-11 07:35:06 | MASTER-OAFA | (05h 21m 07.33s , -46d 16m 40.1s) | C | 60 | 19.9 | 45888 | 2025-09-11 07:36:22 | MASTER-OAFA | (05h 21m 00.65s , -46d 17m 37.5s) | C | 60 | 19.8 | 45962 | 2025-09-11 07:37:36 | MASTER-OAFA | (05h 21m 07.79s , -46d 17m 14.3s) | C | 60 | 19.9 | 46036 | 2025-09-11 07:38:51 | MASTER-OAFA | (05h 21m 04.04s , -46d 15m 34.4s) | C | 60 | 19.9 | 46112 | 2025-09-11 07:40:06 | MASTER-OAFA | (05h 21m 04.05s , -46d 17m 27.2s) | C | 60 | 19.9 | 46187 | 2025-09-11 07:41:21 | MASTER-OAFA | (05h 21m 07.22s , -46d 15m 29.4s) | C | 60 | 19.9 | 46263 | 2025-09-11 07:42:38 | MASTER-OAFA | (05h 21m 00.93s , -46d 16m 25.0s) | C | 60 | 19.9 | 46340 | 2025-09-11 07:43:55 | MASTER-OAFA | (05h 21m 00.54s , -46d 15m 22.3s) | C | 60 | 19.9 | 46417 | 2025-09-11 07:45:11 | MASTER-OAFA | (05h 21m 06.25s , -46d 16m 20.5s) | C | 60 | 19.8 | 46495 | 2025-09-11 07:46:29 | MASTER-OAFA | (05h 21m 01.68s , -46d 17m 18.0s) | C | 60 | 19.9 | 46569 | 2025-09-11 07:47:43 | MASTER-OAFA | (05h 21m 06.17s , -46d 16m 51.8s) | C | 60 | 19.9 | 46645 | 2025-09-11 07:49:00 | MASTER-OAFA | (05h 21m 04.24s , -46d 15m 24.7s) | C | 60 | 19.9 | 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/41791. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39856] EP250911a: LCO optical counterpart discovery
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41790 SUBJECT: EP250911a: LCO optical counterpart discovery DATE: 25/09/11 10:23:38 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> J. A. Quirola-Vasquez (Radboud), R. A. J. Eyles-Ferris (Leicester), D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), A. Martin-Carrillo (UCD), L. Cotter (UCD), P. G. Jonker (Radboud), F. E. Bauer (SSI and UTA), and J. Chacón (PUC) report on behalf of a larger collaboration: We observed the location of EP250911a (Liang et al., GCN 41788) with the Sinistro instrument mounted on the 1-m telescopes at McDonald Observatory, available via the LCO network. 6 x 200 s exposures were obtained in the SDSS r filter at a start time of 2025-09-11 UT 09:35:35 (~37.1 min post trigger). Within the WXT and FXT error circles (Liang et al., GCN 41788) we locate a new source in our stacked r-band image, not visible in the archival Legacy Survey images. Its coordinates (0.5" error) are: RA(J2000): 23:50:04.83 DEC(J2000): +29:17:59.6 Calibrated to nearby stars from the Pan-STARRS catalog, we measure a magnitude r = 20.04 +/- 0.07 (AB), not corrected for Galactic extinction. Given the non-detection in the deeper archival images and the consistency with the FXT error circle, we suggest that this source is the optical counterpart of EP250911a. View this GCN Circular online at https://gcn.nasa.gov/circulars/41790. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39855] EP250910a: Global MASTER-Net observations report
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41789 SUBJECT: EP250910a: Global MASTER-Net observations report DATE: 25/09/11 10:09:24 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) was pointed to the EP250910a ( EP Team et al., GCN 41776) errorbox 829 sec after trigger time at 2025-09-10 03:29:53 UT, with upper limit up to 19.6 mag. The observations began at zenith distance = 54 deg. The sun altitude is -60.2 deg. The galactic latitude b = -64 deg., longitude l = 248 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2989175 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 849 | 2025-09-10 03:29:53 | MASTER-OAFA | (02h 39m 03.43s , -39d 42m 17.1s) | C | 40 | 18.9 | 895 | 2025-09-10 03:30:38 | MASTER-OAFA | (02h 39m 03.40s , -39d 42m 15.3s) | C | 40 | 18.9 | 940 | 2025-09-10 03:31:24 | MASTER-OAFA | (02h 39m 03.42s , -39d 42m 13.6s) | C | 40 | 18.9 | 987 | 2025-09-10 03:32:10 | MASTER-OAFA | (02h 39m 03.36s , -39d 42m 11.4s) | C | 40 | 18.9 | 1032 | 2025-09-10 03:32:55 | MASTER-OAFA | (02h 39m 03.34s , -39d 42m 09.8s) | C | 40 | 18.9 | 1077 | 2025-09-10 03:33:41 | MASTER-OAFA | (02h 39m 03.29s , -39d 42m 08.0s) | C | 40 | 18.9 | 1123 | 2025-09-10 03:34:27 | MASTER-OAFA | (02h 39m 03.28s , -39d 42m 06.1s) | C | 40 | 18.9 | 1169 | 2025-09-10 03:35:13 | MASTER-OAFA | (02h 39m 03.23s , -39d 42m 04.7s) | C | 40 | 18.9 | 1215 | 2025-09-10 03:35:58 | MASTER-OAFA | (02h 39m 03.16s , -39d 42m 03.1s) | C | 40 | 18.8 | 1261 | 2025-09-10 03:36:45 | MASTER-OAFA | (02h 39m 03.15s , -39d 42m 01.5s) | C | 40 | 18.8 | 1306 | 2025-09-10 03:37:30 | MASTER-OAFA | (02h 39m 03.08s , -39d 41m 59.9s) | C | 40 | 18.9 | 1352 | 2025-09-10 03:38:15 | MASTER-OAFA | (02h 39m 03.06s , -39d 41m 58.1s) | C | 40 | 18.9 | 1398 | 2025-09-10 03:39:01 | MASTER-OAFA | (02h 39m 03.03s , -39d 41m 56.4s) | C | 40 | 18.9 | 1443 | 2025-09-10 03:39:46 | MASTER-OAFA | (02h 39m 03.00s , -39d 41m 55.0s) | C | 40 | 18.9 | 1488 | 2025-09-10 03:40:32 | MASTER-OAFA | (02h 39m 02.97s , -39d 41m 53.5s) | C | 40 | 18.9 | 1535 | 2025-09-10 03:41:19 | MASTER-OAFA | (02h 39m 02.93s , -39d 41m 52.0s) | C | 40 | 18.9 | 1580 | 2025-09-10 03:42:04 | MASTER-OAFA | (02h 39m 02.89s , -39d 41m 50.3s) | C | 40 | 18.9 | 1626 | 2025-09-10 03:42:50 | MASTER-OAFA | (02h 39m 02.87s , -39d 41m 49.0s) | C | 40 | 18.9 | 8775 | 2025-09-10 05:41:58 | MASTER-OAFA | (02h 39m 14.92s , -39d 38m 15.4s) | C | 40 | 19.0 | 8820 | 2025-09-10 05:42:44 | MASTER-OAFA | (02h 39m 15.02s , -39d 38m 14.6s) | C | 40 | 19.0 | 8866 | 2025-09-10 05:43:29 | MASTER-OAFA | (02h 39m 15.10s , -39d 38m 13.5s) | C | 40 | 19.0 | 8912 | 2025-09-10 05:44:16 | MASTER-OAFA | (02h 39m 15.16s , -39d 38m 12.2s) | C | 40 | 19.0 | 8958 | 2025-09-10 05:45:01 | MASTER-OAFA | (02h 39m 15.23s , -39d 38m 11.0s) | C | 40 | 19.0 | 9003 | 2025-09-10 05:45:46 | MASTER-OAFA | (02h 39m 15.27s , -39d 38m 09.8s) | C | 40 | 19.1 | 9050 | 2025-09-10 05:46:34 | MASTER-OAFA | (02h 39m 15.35s , -39d 38m 08.4s) | C | 40 | 19.2 | 9096 | 2025-09-10 05:47:19 | MASTER-OAFA | (02h 39m 15.36s , -39d 38m 07.0s) | C | 40 | 19.2 | 9141 | 2025-09-10 05:48:05 | MASTER-OAFA | (02h 39m 15.41s , -39d 38m 05.9s) | C | 40 | 19.2 | 9187 | 2025-09-10 05:48:51 | MASTER-OAFA | (02h 39m 15.48s , -39d 38m 04.6s) | C | 40 | 19.1 | 9233 | 2025-09-10 05:49:36 | MASTER-OAFA | (02h 39m 15.55s , -39d 38m 03.0s) | C | 40 | 19.2 | 9278 | 2025-09-10 05:50:22 | MASTER-OAFA | (02h 39m 15.61s , -39d 38m 01.9s) | C | 40 | 19.3 | 9601 | 2025-09-10 05:55:35 | MASTER-OAFA | (02h 33m 49.69s , -39d 37m 50.4s) | C | 60 | 19.4 | 9677 | 2025-09-10 05:56:51 | MASTER-OAFA | (02h 33m 54.50s , -39d 38m 48.0s) | C | 60 | 19.3 | 9755 | 2025-09-10 05:58:09 | MASTER-OAFA | (02h 33m 49.60s , -39d 39m 45.9s) | C | 60 | 19.4 | 9831 | 2025-09-10 05:59:24 | MASTER-OAFA | (02h 44m 18.55s , -39d 39m 18.6s) | C | 60 | 19.5 | 9907 | 2025-09-10 06:00:40 | MASTER-OAFA | (02h 44m 16.33s , -39d 37m 58.7s) | C | 60 | 19.5 | 9991 | 2025-09-10 06:02:05 | MASTER-OAFA | (02h 44m 16.40s , -39d 39m 33.5s) | C | 60 | 19.5 | 12839 | 2025-09-10 06:49:33 | MASTER-OAFA | (02h 44m 22.49s , -39d 36m 17.7s) | C | 60 | 18.5 | 12914 | 2025-09-10 06:50:48 | MASTER-OAFA | (02h 44m 16.60s , -39d 37m 14.4s) | C | 60 | 18.5 | 12995 | 2025-09-10 06:52:08 | MASTER-OAFA | (02h 44m 16.65s , -39d 36m 12.0s) | C | 60 | 18.5 | 21335 | 2025-09-10 09:11:08 | MASTER-OAFA | (02h 34m 24.31s , -39d 47m 18.9s) | C | 60 | 18.1 | 21411 | 2025-09-10 09:12:25 | MASTER-OAFA | (02h 44m 52.99s , -39d 48m 13.6s) | C | 60 | 18.2 | 21650 | 2025-09-10 09:16:23 | MASTER-OAFA | (02h 34m 27.58s , -39d 47m 23.8s) | C | 60 | 18.0 | 21725 | 2025-09-10 09:17:39 | MASTER-OAFA | (02h 44m 51.45s , -39d 48m 38.3s) | C | 60 | 18.3 | 21885 | 2025-09-10 09:20:18 | MASTER-OAFA | (02h 34m 24.84s , -39d 48m 09.4s) | C | 60 | 18.0 | 23662 | 2025-09-10 09:49:55 | MASTER-OAFA | (02h 44m 54.42s , -39d 48m 19.8s) | C | 60 | 18.1 | 23738 | 2025-09-10 09:51:12 | MASTER-OAFA | (02h 44m 57.09s , -39d 46m 48.8s) | C | 60 | 18.0 | 23814 | 2025-09-10 09:52:27 | MASTER-OAFA | (02h 44m 52.46s , -39d 47m 38.5s) | C | 60 | 17.9 | 108092 | 2025-09-11 09:17:15 | MASTER-OAFA | (02h 34m 29.12s , -39d 47m 30.9s) | C | 40 | 19.6 | 108137 | 2025-09-11 09:18:01 | MASTER-OAFA | (02h 34m 29.19s , -39d 47m 30.2s) | C | 40 | 19.5 | 108183 | 2025-09-11 09:18:46 | MASTER-OAFA | (02h 34m 29.25s , -39d 47m 29.8s) | C | 40 | 19.5 | 108235 | 2025-09-11 09:19:39 | MASTER-OAFA | (02h 34m 29.29s , -39d 47m 29.2s) | C | 40 | 19.5 | 108281 | 2025-09-11 09:20:24 | MASTER-OAFA | (02h 34m 29.36s , -39d 47m 28.6s) | C | 40 | 19.5 | 108326 | 2025-09-11 09:21:10 | MASTER-OAFA | (02h 34m 29.44s , -39d 47m 28.0s) | C | 40 | 19.6 | 108378 | 2025-09-11 09:22:02 | MASTER-OAFA | (02h 34m 29.50s , -39d 47m 27.5s) | C | 40 | 19.5 | 108424 | 2025-09-11 09:22:48 | MASTER-OAFA | (02h 34m 29.55s , -39d 47m 27.0s) | C | 40 | 19.5 | 108469 | 2025-09-11 09:23:33 | MASTER-OAFA | (02h 34m 29.62s , -39d 47m 26.2s) | C | 40 | 19.5 | 108521 | 2025-09-11 09:24:24 | MASTER-OAFA | (02h 34m 29.66s , -39d 47m 25.8s) | C | 40 | 19.5 | 108567 | 2025-09-11 09:25:10 | MASTER-OAFA | (02h 34m 29.74s , -39d 47m 25.1s) | C | 40 | 19.6 | 108612 | 2025-09-11 09:25:56 | MASTER-OAFA | (02h 34m 29.81s , -39d 47m 24.6s) | C | 40 | 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/41789. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39854] EP250911a: Einstein Probe detection of an X-ray transient
by GCN Circulars 11 Sep '25

11 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41788 SUBJECT: EP250911a: Einstein Probe detection of an X-ray transient DATE: 25/09/11 09:56:36 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. F. Liang (PMO), Q. Y. Wu, W. D. Zhang(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 EP250911a. The transient triggered EP-WXT (ID: 01709240741) at 2025-09-11T08:58:28 (UTC). The WXT position of the source is R.A. = 357.532 deg, DEC = 29.286 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. = 357.5204 deg, DEC = 29.3018 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 are 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/41788. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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