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

[vsnet-grb-info 37645] GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
by GCN Circulars 09 Mar '25

09 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39629 SUBJECT: GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318) DATE: 25/03/09 08:04:59 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 763198715 at 07:38:30 on 09 March 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS … [View More]

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[vsnet-grb-info 37644] EP250308a: Global MASTER-Net observations report
by GCN Circulars 09 Mar '25

09 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39628 SUBJECT: EP250308a: Global MASTER-Net observations report DATE: 25/03/09 06:09:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.… [View More]

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[vsnet-grb-info 37643] EP250308a: GSP optical upper limit
by GCN Circulars 09 Mar '25

09 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39627 SUBJECT: EP250308a: GSP optical upper limit DATE: 25/03/09 05:36:15 GMT FROM: Wenxiong Li at NAOC <liwenxiong1992(a)gmail.com> W. X. Li, S. J. Xue (NAOC), M. Andrews, J. Farah, D. A. Howell, M. Newsome, E. Padilla Gonzalez, C. McCully, and G. Terreran (Las Cumbres Observatory), on behalf of a larger collaboration, report: Following the detection of the fast X-ray transient EP250308a by the Einstein Probe (trigger ID: 01709132392; Yin et al., GCN … [View More]

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[vsnet-grb-info 37642] EP250308a: FTW optical and NIR upper limits
by GCN Circulars 09 Mar '25

09 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39626 SUBJECT: EP250308a: FTW optical and NIR upper limits DATE: 25/03/09 05:35:45 GMT FROM: Brendan O'Connor at Carnegie Mellon University <boconno2(a)andrew.cmu.edu> Malte Busmann (LMU), Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU) and Antonella Palmese (Carnegie Mellon U.) report: We observed the 90% of EP-WXT trigger 01709132392, corresponding to EP250308a, with the Three Channel Imager (3KK) at the Fraunhofer Telescope at … [View More]

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[vsnet-grb-info 37641] EP250308a: Einstein Probe detection of an X-ray transient
by GCN Circulars 09 Mar '25

09 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39625 SUBJECT: EP250308a: Einstein Probe detection of an X-ray transient DATE: 25/03/09 05:27:54 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.-H. I. Yin (NJU), Q. Y. Wu (NAO, CAS), J. H. Wu (GZHU), H. W. Pan (NAO, CAS) report on behalf of the Einstein Probe 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 EP250308a. The transient triggered … [View More]

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[vsnet-grb-info 37640] EP250308a: NOT optical upper limit
by GCN Circulars 09 Mar '25

09 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39624 SUBJECT: EP250308a: NOT optical upper limit DATE: 25/03/09 05:18:36 GMT FROM: Zipei Zhu at NAOC <zpzhu(a)nao.cas.cn> Z.P. Zhu, X. Liu, Jie An, S.Q. Jiang, D. Xu (NAOC), S.Y. Fu (HUST, NAOC), D. B. Malesani (DAWN/NBI and Radboud U.), P. Jonker (Radboud U.), A. H. Fuente (NOT) report on behalf of a large collaboration: We observed the field of EP250308a detected by EP/WXT (Trigger ID: 01709132392), using the ALFOSC instruments mounted on the … [View More]

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[vsnet-grb-info 37639] GRB 250309A: Fermi GBM Final Real-time Localization
by GCN Circulars 09 Mar '25

09 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39623 SUBJECT: GRB 250309A: Fermi GBM Final Real-time Localization DATE: 25/03/09 00:53:02 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 00:42:03 UT on 9 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250309A (trigger 763173728.785018 / 250309029). The on-ground calculated location, using the Fermi GBM trigger data, is RA =… [View More]

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[vsnet-grb-info 37638] GRB 250306A: EIRSAT-1 GMOD detection
by GCN Circulars 08 Mar '25

08 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39622 SUBJECT: GRB 250306A: EIRSAT-1 GMOD detection DATE: 25/03/08 19:48:12 GMT FROM: Cuán de Barra at UCD <cuan.debarra(a)ucdconnect.ie> C. de Barra, D. Murphy, C. McKenna, A. Ulyanov, P. McDermott, G. Finneran, M. Doyle, R. Dunwoody, J. Mangan, G. Corcoran, L. Cotter, A. Empey, J. Fisher, F. Gibson Kiely, J. Thompson, D. McKeown, A. Martin-Carrillo, L. Hanlon, S. McBreen, on behalf of the EIRSAT-1 team: EIRSAT-1 reports the detection of the long … [View More]

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[vsnet-grb-info 37637] The EP-WXT trigger 01709132387 is likely a flaring star
by GCN Circulars 08 Mar '25

08 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39621 SUBJECT: The EP-WXT trigger 01709132387 is likely a flaring star DATE: 25/03/08 02:02:24 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. C. Liu (THU), Y.-H. I. Yin (NJU), H. Y. Liu, W. Yuan (NAO, CAS) report on behalf of the Einstein Probe team: The EP-WXT trigger (ID: 01709132387) on 2025-03-07 18:51:20 (UTC) is likely a stellar flare associated with a young stellar object candidate Gaia DR3 6093234407369953024. Launched on January 9, … [View More]

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[vsnet-grb-info 37636] Fermi GRB 250307A: Global MASTER-Net observations report
by GCN Circulars 08 Mar '25

08 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39620 SUBJECT: Fermi GRB 250307A: Global MASTER-Net observations report DATE: 25/03/08 00:30:39 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta,… [View More] R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), 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 250307A ( Fermi GBM team, GCN 39618) errorbox 12559 sec after notice time and 12601 sec after trigger time at 2025-03-07 23:27:54 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 70 deg. The sun altitude is -42.9 deg. The galactic latitude b = 16 deg., longitude l = 27 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2803750 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 12631 | 2025-03-07 23:27:54 | MASTER-Kislovodsk | (17h 39m 34.52s , +03d 16m 16.2s) | C | 60 | 16.0 | 13390 | 2025-03-07 23:40:34 | MASTER-Kislovodsk | (17h 47m 30.44s , +03d 15m 20.9s) | C | 60 | 16.9 | 13470 | 2025-03-07 23:41:53 | MASTER-Kislovodsk | (17h 39m 36.28s , +03d 16m 01.7s) | C | 60 | 17.1 | 13550 | 2025-03-07 23:43:13 | MASTER-Kislovodsk | (17h 38m 11.65s , +01d 21m 58.9s) | C | 60 | 16.9 | 15377 | 2025-03-08 00:13:10 | MASTER-Kislovodsk | (17h 40m 28.55s , +02d 25m 26.0s) | C | 120 | 17.0 | 15517 | 2025-03-08 00:15:30 | MASTER-Kislovodsk | (17h 40m 32.95s , +02d 24m 17.6s) | C | 120 | 17.7 | 15656 | 2025-03-08 00:17:49 | MASTER-Kislovodsk | (17h 40m 27.31s , +00d 23m 17.3s) | C | 120 | 17.9 | 15796 | 2025-03-08 00:20:09 | MASTER-Kislovodsk | (17h 40m 31.50s , +00d 23m 28.7s) | C | 120 | 17.9 | 16015 | 2025-03-08 00:24:18 | MASTER-Kislovodsk | (17h 40m 31.73s , +02d 23m 54.6s) | C | 60 | 17.1 | 16095 | 2025-03-08 00:25:39 | MASTER-Kislovodsk | (17h 46m 12.95s , +01d 24m 43.6s) | C | 60 | 17.4 | 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/39620. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37635] Konus-Wind detection of GRB 250306A
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39619 SUBJECT: Konus-Wind detection of GRB 250306A DATE: 25/03/07 22:30:19 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 250306A (Swift-BAT detection: Evans et al., GCN 39606; Astrosat-CZTI detection: Tembhurnikar et al., GCN 39611) triggered Konus-Wind at T0=59404.612 s UT (16:… [View More]

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[vsnet-grb-info 37634] GRB 250307A: Fermi GBM Final Real-time Localization
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39618 SUBJECT: GRB 250307A: Fermi GBM Final Real-time Localization DATE: 25/03/07 20:08:14 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 19:57:53 UT on 7 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250307A (trigger 763070278.733804 / 250307832). The on-ground calculated location, using the Fermi GBM trigger data, is RA = … [View More]

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[vsnet-grb-info 37633] GRB 250306A: Swift-BAT refined analysis
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39617 SUBJECT: GRB 250306A: Swift-BAT refined analysis DATE: 25/03/07 18:38:30 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> T. Parsotan (GSFC), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-… [View More]

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[vsnet-grb-info 37632] GRB 250306A: NuSTAR detection of the prompt emission
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39616 SUBJECT: GRB 250306A: NuSTAR detection of the prompt emission DATE: 25/03/07 17:27:29 GMT FROM: Brian Grefenstette at Caltech/NuSTAR <bwgref(a)srl.caltech.edu> B. Grefenstette (Caltech) reports on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group: The NuSTAR SINGS working group reports the detection of prompt emission from the Long GRB 250306A in both the NuSTAR CsI anti-coincidence shields. This GRB was … [View More]

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[vsnet-grb-info 37631] EP250304a: MeerKAT detection of a possible radio counterpart
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39615 SUBJECT: EP250304a: MeerKAT detection of a possible radio counterpart DATE: 25/03/07 16:30:01 GMT FROM: Francesco Carotenuto at INAF/OAR <francesco.carotenuto(a)inaf.it> F. Carotenuto (INAF/OAR), J. Bright (University of Oxford), P. G. Jonker (Radboud University) report on behalf of a larger collaboration: We observed the Fast X-ray Transient EP250304a (Chen et al., GCN 39580) with the MeerKAT radio telescope at 3.0 GHz for a total of 1 hour … [View More]

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[vsnet-grb-info 37630] IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39614 SUBJECT: IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect DATE: 25/03/07 13:19:38 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> K. Labzina, K.Zhirkov, V.Lipunov, E.Gorbovskoy, A.Kuznetsov, G.Antipov, D.Vlasenko, A.Kuznetsov, N.Tyurina, P.Balanutsa, A.Chasovnikov, V.Topolev, Ya.Kechin, V.Senik, Yu.Tselik (Lomonosov MSU), O.Gress, N.Budnev, O.Ershova (ISU), C.Francile, F. … [View More]

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[vsnet-grb-info 37629] GRB 250305A: AstroSat CZTI detection
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39613 SUBJECT: GRB 250305A: AstroSat CZTI detection DATE: 25/03/07 12:11:29 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> M. Tembhurnikar (IUCAA), J. Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma … [View More]

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[vsnet-grb-info 37628] EP250302a:Xinglong optical observations
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39612 SUBJECT: EP250302a:Xinglong optical observations DATE: 25/03/07 09:55:58 GMT FROM: Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong(a)nao.cas.cn> Junjie-Jin (NAOC), Haiyang-Mu (NAOC), Jinlei-Zhang (NAOC), Pengliang-Du (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report: We performed optical observations of the field of a fast X-Ray transient EP250302a (Zhu et. al, GCN 39550; ) in the g, … [View More]

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[vsnet-grb-info 37627] GRB 250306A: AstroSat CZTI detection
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39611 SUBJECT: GRB 250306A: AstroSat CZTI detection DATE: 25/03/07 05:36:41 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> M. Tembhurnikar (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA,… [View More]

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[vsnet-grb-info 37626] Fermi trigger No 762963055: Global MASTER-Net observations report
by GCN Circulars 07 Mar '25

07 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39610 SUBJECT: Fermi trigger No 762963055: Global MASTER-Net observations report DATE: 25/03/07 03:31:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, … [View More]F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB250306.59 (trigger No 762963055,06h 29m 04.08s , -54d 04m 58.8s, R=50) errorbox 19549 sec after notice time and 19583 sec after trigger time at 2025-03-06 19:37:13 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 44 deg. The sun altitude is -30.8 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB250306.59 errorbox 35961 sec after notice time and 35994 sec after trigger time at 2025-03-07 00:10:45 UT, with upper limit up to 20.7 mag. Observations started at twilight. The observations began at zenith distance = 6 deg. The sun altitude is -15.1 deg. The galactic latitude b = -25 deg., longitude l = 263 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2802407 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 19613 | 2025-03-06 19:37:13 | MASTER-SAAO | (04h 20m 33.85s , -55d 04m 29.3s) | C | 60 | 17.8 | 19692 | 2025-03-06 19:38:32 | MASTER-SAAO | (04h 20m 41.18s , -55d 05m 26.6s) | B | 60 | 17.9 | 19942 | 2025-03-06 19:42:42 | MASTER-SAAO | (07h 23m 40.55s , -50d 13m 46.6s) | C | 60 | 18.8 | 20021 | 2025-03-06 19:44:01 | MASTER-SAAO | (07h 35m 57.04s , -50d 14m 19.6s) | C | 60 | 18.7 | 20101 | 2025-03-06 19:45:21 | MASTER-SAAO | (06h 59m 31.94s , -57d 50m 20.3s) | C | 60 | 19.1 | 20180 | 2025-03-06 19:46:40 | MASTER-SAAO | (07h 14m 17.76s , -57d 51m 12.6s) | C | 60 | 18.9 | 20259 | 2025-03-06 19:47:59 | MASTER-SAAO | (06h 53m 09.68s , -59d 43m 41.7s) | C | 60 | 19.3 | 20339 | 2025-03-06 19:49:19 | MASTER-SAAO | (07h 08m 50.79s , -59d 44m 59.4s) | C | 60 | 19.1 | 20418 | 2025-03-06 19:50:38 | MASTER-SAAO | (06h 38m 47.19s , -55d 56m 27.1s) | C | 60 | 18.9 | 20497 | 2025-03-06 19:51:57 | MASTER-SAAO | (06h 52m 56.67s , -55d 55m 18.5s) | C | 60 | 18.9 | 20576 | 2025-03-06 19:53:17 | MASTER-SAAO | (04h 20m 40.87s , -55d 05m 06.1s) | C | 60 | 17.4 | 20855 | 2025-03-06 19:57:55 | MASTER-SAAO | (04h 20m 41.15s , -55d 05m 19.8s) | B | 60 | 17.8 | 21511 | 2025-03-06 20:08:52 | MASTER-SAAO | (07h 23m 44.10s , -50d 12m 41.1s) | C | 60 | 18.9 | 21591 | 2025-03-06 20:10:11 | MASTER-SAAO | (07h 36m 14.00s , -50d 13m 36.1s) | C | 60 | 18.7 | 21671 | 2025-03-06 20:11:31 | MASTER-SAAO | (06h 59m 37.99s , -57d 50m 34.1s) | C | 60 | 19.1 | 21750 | 2025-03-06 20:12:50 | MASTER-SAAO | (07h 14m 35.51s , -57d 50m 12.8s) | C | 60 | 19.0 | 21829 | 2025-03-06 20:14:10 | MASTER-SAAO | (06h 53m 20.12s , -59d 42m 57.5s) | C | 60 | 19.2 | 22516 | 2025-03-06 20:25:36 | MASTER-SAAO | (07h 09m 03.43s , -59d 41m 59.2s) | C | 60 | 19.1 | 22595 | 2025-03-06 20:26:55 | MASTER-SAAO | (06h 39m 05.00s , -55d 55m 13.9s) | C | 60 | 19.0 | 22675 | 2025-03-06 20:28:15 | MASTER-SAAO | (06h 53m 08.87s , -55d 56m 07.8s) | C | 60 | 19.0 | 23012 | 2025-03-06 20:33:52 | MASTER-SAAO | (07h 23m 52.89s , -50d 13m 01.7s) | C | 60 | 18.9 | 23091 | 2025-03-06 20:35:11 | MASTER-SAAO | (07h 36m 17.11s , -50d 11m 56.0s) | C | 60 | 18.8 | 23171 | 2025-03-06 20:36:31 | MASTER-SAAO | (06h 59m 51.87s , -57d 48m 49.5s) | C | 60 | 19.1 | 23250 | 2025-03-06 20:37:50 | MASTER-SAAO | (07h 14m 37.85s , -57d 49m 43.0s) | C | 60 | 18.9 | 23329 | 2025-03-06 20:39:09 | MASTER-SAAO | (06h 53m 30.83s , -59d 43m 41.5s) | C | 60 | 19.2 | 23583 | 2025-03-06 20:43:24 | MASTER-SAAO | (07h 09m 06.81s , -59d 42m 35.4s) | C | 60 | 19.1 | 23663 | 2025-03-06 20:44:43 | MASTER-SAAO | (06h 39m 02.04s , -55d 53m 45.9s) | C | 60 | 18.9 | 23742 | 2025-03-06 20:46:02 | MASTER-SAAO | (06h 53m 18.74s , -55d 54m 38.5s) | C | 60 | 18.9 | 24154 | 2025-03-06 20:52:54 | MASTER-SAAO | (07h 24m 04.89s , -50d 11m 37.4s) | C | 60 | 18.9 | 24233 | 2025-03-06 20:54:14 | MASTER-SAAO | (07h 36m 22.74s , -50d 12m 22.2s) | C | 60 | 18.8 | 24313 | 2025-03-06 20:55:33 | MASTER-SAAO | (06h 59m 48.96s , -57d 47m 13.8s) | C | 60 | 19.0 | 24392 | 2025-03-06 20:56:52 | MASTER-SAAO | (07h 14m 48.32s , -57d 48m 07.9s) | C | 60 | 18.9 | 24471 | 2025-03-06 20:58:12 | MASTER-SAAO | (06h 53m 27.53s , -59d 43m 09.8s) | C | 60 | 19.3 | 24724 | 2025-03-06 21:02:24 | MASTER-SAAO | (07h 09m 15.67s , -59d 42m 55.8s) | C | 60 | 19.2 | 24804 | 2025-03-06 21:03:44 | MASTER-SAAO | (06h 39m 12.98s , -55d 53m 12.3s) | C | 60 | 18.9 | 24883 | 2025-03-06 21:05:03 | MASTER-SAAO | (06h 53m 17.91s , -55d 54m 02.0s) | C | 60 | 19.0 | 25374 | 2025-03-06 21:13:14 | MASTER-SAAO | (07h 24m 10.09s , -50d 10m 53.7s) | C | 60 | 18.8 | 25453 | 2025-03-06 21:14:33 | MASTER-SAAO | (07h 36m 29.33s , -50d 11m 44.1s) | C | 60 | 18.7 | 25532 | 2025-03-06 21:15:52 | MASTER-SAAO | (06h 59m 55.42s , -57d 46m 33.9s) | C | 60 | 18.9 | 25611 | 2025-03-06 21:17:12 | MASTER-SAAO | (07h 14m 54.90s , -57d 47m 28.2s) | C | 60 | 18.8 | 25691 | 2025-03-06 21:18:31 | MASTER-SAAO | (06h 53m 33.13s , -59d 42m 29.2s) | C | 60 | 19.1 | 26024 | 2025-03-06 21:24:04 | MASTER-SAAO | (07h 09m 24.68s , -59d 40m 41.5s) | C | 60 | 19.1 | 26103 | 2025-03-06 21:25:24 | MASTER-SAAO | (06h 39m 10.31s , -55d 53m 24.4s) | C | 60 | 19.0 | 26183 | 2025-03-06 21:26:43 | MASTER-SAAO | (06h 53m 20.72s , -55d 52m 17.4s) | C | 60 | 18.5 | 26681 | 2025-03-06 21:35:01 | MASTER-SAAO | (07h 24m 19.80s , -50d 10m 26.5s) | C | 60 | 17.3 | 26761 | 2025-03-06 21:36:21 | MASTER-SAAO | (07h 36m 38.64s , -50d 11m 15.0s) | C | 60 | 17.4 | 26840 | 2025-03-06 21:37:40 | MASTER-SAAO | (07h 00m 03.51s , -57d 46m 05.9s) | C | 60 | 17.6 | 26919 | 2025-03-06 21:38:59 | MASTER-SAAO | (07h 15m 04.43s , -57d 46m 59.8s) | C | 60 | 16.8 | 26999 | 2025-03-06 21:40:19 | MASTER-SAAO | (06h 53m 40.23s , -59d 42m 01.2s) | C | 60 | 17.6 | 27330 | 2025-03-06 21:45:50 | MASTER-SAAO | (07h 09m 30.05s , -59d 40m 08.9s) | C | 60 | 19.1 | 27409 | 2025-03-06 21:47:09 | MASTER-SAAO | (06h 39m 13.36s , -55d 52m 47.5s) | C | 60 | 18.9 | 27488 | 2025-03-06 21:48:28 | MASTER-SAAO | (06h 53m 25.38s , -55d 51m 40.4s) | C | 60 | 19.1 | 36055 | 2025-03-07 00:10:45 | MASTER-OAFA | (06h 39m 01.49s , -36d 27m 29.2s) | C | 120 | 20.0 | 36175 | 2025-03-07 00:10:45 | MASTER-OAFA | (06h 39m 01.49s , -36d 27m 29.2s) | C | 360 | 20.5 | Coadd 36492 | 2025-03-07 00:18:13 | MASTER-OAFA | (06h 50m 23.77s , -36d 05m 00.8s) | C | 100 | 18.4 | 36592 | 2025-03-07 00:18:13 | MASTER-OAFA | (06h 50m 23.77s , -36d 05m 00.8s) | C | 300 | 19.1 | Coadd 36503 | 2025-03-07 00:18:13 | MASTER-OAFA | (06h 39m 02.29s , -36d 26m 20.3s) | C | 120 | 19.9 | 36626 | 2025-03-07 00:20:26 | MASTER-OAFA | (06h 50m 31.45s , -36d 05m 57.5s) | C | 100 | 18.5 | 36636 | 2025-03-07 00:20:27 | MASTER-OAFA | (06h 39m 09.85s , -36d 27m 17.1s) | C | 120 | 20.1 | 36763 | 2025-03-07 00:22:43 | MASTER-OAFA | (06h 50m 26.25s , -36d 06m 54.0s) | C | 100 | 18.5 | 36773 | 2025-03-07 00:22:44 | MASTER-OAFA | (06h 39m 04.58s , -36d 28m 13.9s) | C | 120 | 20.0 | 36893 | 2025-03-07 00:22:44 | MASTER-OAFA | (06h 39m 04.58s , -36d 28m 13.9s) | C | 360 | 20.6 | Coadd 36899 | 2025-03-07 00:24:59 | MASTER-OAFA | (06h 50m 31.50s , -36d 06m 22.8s) | C | 100 | 18.5 | 36909 | 2025-03-07 00:25:00 | MASTER-OAFA | (06h 39m 09.97s , -36d 27m 43.2s) | C | 120 | 20.1 | 37253 | 2025-03-07 00:30:54 | MASTER-OAFA | (06h 50m 28.93s , -36d 06m 37.9s) | C | 100 | 18.5 | 37264 | 2025-03-07 00:30:54 | MASTER-OAFA | (06h 39m 07.66s , -36d 28m 03.4s) | C | 120 | 20.0 | 37674 | 2025-03-07 00:38:24 | MASTER-OAFA | (03h 08m 25.09s , -30d 36m 24.1s) | C | 40 | 18.0 | 37714 | 2025-03-07 00:38:24 | MASTER-OAFA | (03h 08m 25.09s , -30d 36m 24.0s) | C | 120 | 18.9 | Coadd 37684 | 2025-03-07 00:38:24 | MASTER-OAFA | (02h 57m 52.08s , -30d 57m 32.7s) | C | 60 | 20.0 | 37744 | 2025-03-07 00:38:24 | MASTER-OAFA | (02h 57m 52.07s , -30d 57m 32.8s) | C | 180 | 20.6 | Coadd 37854 | 2025-03-07 00:41:24 | MASTER-OAFA | (02h 47m 43.33s , -45d 51m 10.7s) | C | 40 | 18.1 | 37894 | 2025-03-07 00:41:24 | MASTER-OAFA | (02h 47m 43.32s , -45d 51m 10.6s) | C | 120 | 18.8 | Coadd 37864 | 2025-03-07 00:41:24 | MASTER-OAFA | (02h 34m 39.52s , -46d 11m 20.6s) | C | 60 | 20.0 | 37924 | 2025-03-07 00:41:24 | MASTER-OAFA | (02h 34m 39.52s , -46d 11m 20.6s) | C | 180 | 20.7 | Coadd 38489 | 2025-03-07 00:51:59 | MASTER-OAFA | (03h 08m 20.31s , -30d 35m 34.4s) | C | 40 | 18.0 | 38499 | 2025-03-07 00:51:59 | MASTER-OAFA | (02h 57m 47.83s , -30d 56m 40.0s) | C | 60 | 19.7 | 38567 | 2025-03-07 00:53:18 | MASTER-OAFA | (02h 47m 44.07s , -45d 50m 28.4s) | C | 40 | 18.1 | 38578 | 2025-03-07 00:53:18 | MASTER-OAFA | (02h 34m 40.86s , -46d 10m 33.0s) | C | 60 | 19.9 | 39176 | 2025-03-07 01:03:27 | MASTER-OAFA | (03h 08m 26.89s , -30d 36m 25.0s) | C | 40 | 18.0 | 39187 | 2025-03-07 01:03:27 | MASTER-OAFA | (02h 57m 54.21s , -30d 57m 33.5s) | C | 60 | 19.9 | 39256 | 2025-03-07 01:04:46 | MASTER-OAFA | (02h 47m 39.18s , -45d 50m 51.5s) | C | 40 | 17.9 | 39266 | 2025-03-07 01:04:47 | MASTER-OAFA | (02h 34m 35.84s , -46d 10m 58.8s) | C | 60 | 20.1 | 39769 | 2025-03-07 01:13:19 | MASTER-OAFA | (03h 08m 27.01s , -30d 37m 51.1s) | C | 40 | 18.0 | 39809 | 2025-03-07 01:13:19 | MASTER-OAFA | (03h 08m 27.01s , -30d 37m 51.0s) | C | 120 | 18.7 | Coadd 39779 | 2025-03-07 01:13:19 | MASTER-OAFA | (02h 57m 54.90s , -30d 58m 54.2s) | C | 60 | 19.7 | 39839 | 2025-03-07 01:13:19 | MASTER-OAFA | (02h 57m 54.90s , -30d 58m 54.2s) | C | 180 | 20.4 | Coadd 40225 | 2025-03-07 01:20:55 | MASTER-OAFA | (02h 47m 38.97s , -45d 50m 05.2s) | C | 40 | 17.9 | 40235 | 2025-03-07 01:20:55 | MASTER-OAFA | (02h 34m 36.00s , -46d 10m 14.5s) | C | 60 | 20.1 | 40574 | 2025-03-07 01:26:45 | MASTER-OAFA | (03h 08m 27.40s , -30d 38m 14.0s) | C | 40 | 17.7 | 40585 | 2025-03-07 01:26:45 | MASTER-OAFA | (02h 57m 55.08s , -30d 59m 20.9s) | C | 60 | 19.6 | 41242 | 2025-03-07 01:37:42 | MASTER-OAFA | (02h 34m 44.51s , -46d 11m 34.8s) | C | 60 | 19.1 | 41646 | 2025-03-07 01:44:36 | MASTER-OAFA | (03h 08m 24.70s , -30d 38m 19.6s) | C | 40 | 17.9 | 41656 | 2025-03-07 01:44:37 | MASTER-OAFA | (02h 57m 52.88s , -30d 59m 23.8s) | C | 60 | 19.3 | 41875 | 2025-03-07 01:48:25 | MASTER-OAFA | (02h 47m 42.83s , -45d 51m 36.8s) | C | 40 | 17.9 | 41885 | 2025-03-07 01:48:25 | MASTER-OAFA | (02h 34m 40.19s , -46d 11m 44.0s) | C | 60 | 19.6 | 47204 | 2025-03-07 03:17:15 | MASTER-OAFA | (12h 16m 47.66s , -65d 25m 24.4s) | C | 40 | 16.7 | 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/39610. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37625] Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39609 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB DATE: 25/03/06 22:57:36 GMT FROM: Matt Godwin <msg0028(a)uah.edu> Matt Godwin (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 762963055/250306591 at 14:10:50.74 UT on 06 March 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to an accidental trigger." … [View More]

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[vsnet-grb-info 37624] Swift GRB 250306A: Global MASTER-Net observations report
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39608 SUBJECT: Swift GRB 250306A: Global MASTER-Net observations report DATE: 25/03/06 18:13:38 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta,… [View More]

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[vsnet-grb-info 37623] LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39607 SUBJECT: LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume DATE: 25/03/06 17:03:36 GMT FROM: David Cook at Caltech/IPAC-NED <dcook(a)ipac.caltech.edu> David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC) On behalf of the NASA/IPAC Extragalactic Database (NED) Team. We spatially cross-matched … [View More]the LVK S250207bg-5-Update sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023), which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 369 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links: Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S250207bg/5 Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S250207bg/5/20 *** We note that the version of NED-LVS used in this analysis is from Jan 2025 that was released on Feb 10 2025, whereas the S250207bg-4-Update analysis used the previous version. This new version has an additional 203K galaxies in the full sample the majority of which are from DESI-EDR. The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D * P_SFR; and specific star formation rate, P_3D * P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume. | objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV| m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1| |-------------------------|--------------|--------------|-------|-----------|-----------|------------|------------|------------|------------|------------|------------|--------|----------| | CGCG 184-039| 164.42690| 37.65455| G| 162.22| 26.21| null| null| 10.680| 0.054| 10.878| 0.006|8.03e-05| 1.12e-06| | MCG +06-24-041| 164.47481| 37.54192| G| 162.22| 26.21| 20.279| 0.148| 11.298| 0.055| 11.331| 0.007|9.63e-05| 8.84e-07| | CGCG 184-023| 162.54517| 35.03369| G| 183.12| 0.03| 17.688| 0.031| 12.087| 0.052| 11.752| 0.008|8.79e-05| 6.97e-07| | CGCG 184-033| 163.24603| 37.61345| G| 187.51| 0.05| null| null| 11.034| 0.043| 11.024| 0.006|4.07e-05| 6.62e-07| |WISEA J105523.87+362209.7| 163.84948| 36.36938| G| 151.73| 0.05| 21.139| 0.087| 12.289| 0.075| 12.390| 0.018|2.11e-04| 6.38e-07| |WISEA J105133.05+360501.0| 162.88772| 36.08364| G| 188.40| 44.45| null| null| 12.941| 0.092| 12.598| 0.010|1.58e-04| 6.09e-07| | MCG +06-24-040| 164.47226| 37.51474| G| 149.83| 0.04| 19.652| 0.099| 11.734| 0.062| 11.636| 0.007|1.01e-04| 5.94e-07| | 2MFGC 08396| 161.78556| 34.83804| G| 195.44| 0.05| null| null| 12.218| 0.063| 11.971| 0.009|7.37e-05| 5.44e-07| |WISEA J105802.45+364004.6| 164.51022| 36.66795| G| 141.05| 33.28| 21.365| 0.346| 12.356| 0.057| 12.181| 0.007|1.63e-04| 5.17e-07| |WISEA J104944.42+362416.4| 162.43511| 36.40456| G| 181.79| 0.05| null| null| 12.607| 0.089| 12.522| 0.009|1.21e-04| 4.65e-07| |WISEA J105909.94+371504.2| 164.79142| 37.25117| G| 187.86| null| 18.157| 0.034| 11.855| 0.050| 11.585| 0.007|4.77e-05| 4.64e-07| | 2MFGC 08535| 164.22259| 37.59752| G| 157.75| 0.07| 21.513| 0.332| 12.030| 0.059| 11.685| 0.007|7.16e-05| 4.48e-07| |WISEA J105800.68+374606.5| 164.50287| 37.76849| G| 151.47| 0.04| 20.580| 0.135| 11.774| 0.046| 11.693| 0.007|7.45e-05| 4.27e-07| |WISEA J104451.00+353606.0| 161.21250| 35.60167| G| 229.57| 0.05| null| null| 13.208| 0.103| 11.860| 0.009|3.62e-05| 4.09e-07| | 2MFGC 08400| 161.86882| 36.82418| G| 158.37| 0.05| null| null| 10.992| 0.033| 10.891| 0.006|2.92e-05| 3.83e-07| |WISEA J105511.98+365943.1| 163.79993| 36.99531| G| 194.37| 0.04| 19.438| 0.024| 12.725| 0.093| 12.580| 0.012|7.82e-05| 3.26e-07| |WISEA J105456.98+375126.3| 163.73744| 37.85731| G| 153.99| 0.12| null| null| 15.333| 0.275| 11.308| 0.007|3.85e-05| 3.25e-07| |WISEA J105258.79+371636.7| 163.24498| 37.27688| G| 190.48| 0.05| null| null| 12.533| 0.066| 12.424| 0.008|6.96e-05| 3.21e-07| |WISEA J105855.76+370625.3| 164.73237| 37.10705| G| 157.95| 0.10| 18.116| 0.038| 12.805| 0.115| 12.824| 0.010|1.29e-04| 2.83e-07| |WISEA J105412.49+373218.9| 163.55205| 37.53859| G| 135.45| 0.04| 20.135| 0.181| 11.549| 0.047| 11.403| 0.006|4.57e-05| 2.73e-07| Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S250207bg sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D * P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1). View this GCN Circular online at https://gcn.nasa.gov/circulars/39607. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37622] GRB 250306A: Swift detection of a burst
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39606 SUBJECT: GRB 250306A: Swift detection of a burst DATE: 25/03/06 16:51:42 GMT FROM: David Palmer at LANL <palmer(a)lanl.gov> P. A. Evans (U Leicester), R. Gupta (NASA GSFC), J. A. Kennea (PSU), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 16:30:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250306A (trigger=1293340). Swift did not slew to the burst. The … [View More]

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[vsnet-grb-info 37621] LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39605 SUBJECT: LIGO/Virgo/KAGRA S250207bg: Updated Sky localization DATE: 25/03/06 16:37:39 GMT FROM: Sylvia Biscoveanu at Northwestern CIERA <sylvia.biscoveanu(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (… [View More]CBC) candidate S250207bg (GCN Circulars 39201 and 39242). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline1.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250207bg For the Bilby.offline1.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 19 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis): icrs; ellipse(10h51m, +36d04m, 3.72d, 1.66d, 139.66d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 180 +/- 38 Mpc (a posteriori mean +/- standard deviation). At the time of the candidate, the Hanford detector was being brought online and was not in observing mode. However, it was determined that the Hanford data are sufficiently robust to inform our estimate of the sky localization. The well-measured arrival time of the signal at Hanford, while consistent with the Livingston and Virgo data, breaks the degeneracy in sky localization inherent in a 2-detector analysis, and significantly shifts the posterior distribution with respect to the earlier localization. Further investigations are ongoing to understand how the operational state of Hanford at the time of the event impacts this analysis. The estimated sky localization may change slightly based on these studies, but this skymap represents our best understanding of the event at this time. 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. (2023) arXiv:2307.13380 View this GCN Circular online at https://gcn.nasa.gov/circulars/39605. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37620] GRB250101A: Radio upper limits from VLA observations
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39604 SUBJECT: GRB250101A: Radio upper limits from VLA observations DATE: 25/03/06 15:57:17 GMT FROM: Arvind Balasubramanian <arvind6895(a)gmail.com> A. Balasubramanian (IIA), A.P. Saikia (IITB), V. Swain (IITB), G.C. Anupama (IIA), S. Barway (IIA), V. Bhalerao (IITB) report We observed the field of the gamma ray burst GRB250101A (Page et al. GCN 38752, Li et al. GCN 38753, Mohan et al. GCN 38754, Zhu et al. GCN 38755, Budnev et al. GCN 38756, Wu et … [View More]

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[vsnet-grb-info 37619] LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39603 SUBJECT: LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate DATE: 25/03/06 15:31:48 GMT FROM: Mayank Chaturvedi at RRCAT, INDORE. <mayankc1947(a)gmail.com> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: The trigger S250306ej is no longer considered to be a candidate of interest. This candidate was initially identified by one or more early-warning analyses by matching … [View More]

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[vsnet-grb-info 37618] GRB 250305A: SVOM/GRM observation of a burst
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39602 SUBJECT: GRB 250305A: SVOM/GRM observation of a burst DATE: 25/03/06 09:51:52 GMT FROM: zhangjinpeng(a)ihep.ac.cn SVOM/GRM team: Jin-Peng Zhang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia (IRAP), Frédéric Piron (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 250305A (SVOM burst-id … [View More]

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[vsnet-grb-info 37617] The EP-WXT trigger 01709132323 is likely a flaring star
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39601 SUBJECT: The EP-WXT trigger 01709132323 is likely a flaring star DATE: 25/03/06 09:42:08 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.-H. I. Yin (NJU), H. Sun, X. P. Xu, C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: The EP-WXT trigger (ID: 01709132323) on 2025-03-06 09:04:17 (UTC) is likely a stellar flare associated with a star TYC 2497-986-1. The estimated flux of the flare is around 1.2 x 10^-10 erg/s/cm^2 in 0.5-4.… [View More]

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[vsnet-grb-info 37616] EP250304A: Upper limits from Fermi-GBM Observations
by GCN Circulars 06 Mar '25

06 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39600 SUBJECT: EP250304A: Upper limits from Fermi-GBM Observations DATE: 25/03/06 09:13:06 GMT FROM: mariaedvige.ravasio(a)ru.nl M. E. Ravasio (Radboud Univ.), E. Burns (LSU), and P.G. Jonker (Radboud Univ.) report on behalf of the Fermi-GBM Team: At the starting time T0=2025-03-04T01:29:49 UTC of the EP-WXT event EP250304A (Zhang et al., GCN 39591), Fermi was in South Atlantic Anomaly (SAA). Fermi-GBM had exited SAA approximately 50 seconds after T0. … [View More]

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[vsnet-grb-info 37615] Fermi GRB 250305A: Global MASTER-Net observations report
by GCN Circulars 05 Mar '25

05 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39599 SUBJECT: Fermi GRB 250305A: Global MASTER-Net observations report DATE: 25/03/05 21:32:49 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta,… [View More] R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250305A ( Fermi GBM team, GCN 39597) errorbox 20388 sec after notice time and 20424 sec after trigger time at 2025-03-05 21:09:22 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 78 deg. The sun altitude is -45.2 deg. The galactic latitude b = 47 deg., longitude l = 353 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2801332 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 20455 | 2025-03-05 21:09:22 | MASTER-SAAO | (14h 34m 50.28s , -02d 29m 23.3s) | C | 60 | 18.3 | 20534 | 2025-03-05 21:10:41 | MASTER-SAAO | (14h 42m 45.22s , -02d 30m 38.4s) | C | 60 | 18.4 | 20613 | 2025-03-05 21:12:01 | MASTER-SAAO | (14h 36m 36.01s , -04d 22m 25.4s) | C | 60 | 18.6 | 20772 | 2025-03-05 21:14:39 | MASTER-SAAO | (14h 44m 39.80s , -04d 22m 36.6s) | C | 60 | 18.5 | 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/39599. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37614] Fermi-LAT Gamma-ray Observations of IceCube-250302A
by GCN Circulars 05 Mar '25

05 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39598 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-250302A DATE: 25/03/05 18:12:45 GMT FROM: chiara.bartolini-1(a)unitn.it C. Bartolini (INFN Bari), S. Buson (DESY, Univ. of Wuerzburg), S. Garrappa (Weizmann Institute of Science), L. Pfeiffer (Univ. of Wuerzburg) and P. M. Veres (Ruhr University Bochum) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC250302A neutrino event (GCN … [View More]

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[vsnet-grb-info 37613] GRB 250305A: Fermi GBM Final Real-time Localization
by GCN Circulars 05 Mar '25

05 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39597 SUBJECT: GRB 250305A: Fermi GBM Final Real-time Localization DATE: 25/03/05 15:39:31 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 15:28:57 UT on 5 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250305A (trigger 762881342.919284 / 250305645). The on-ground calculated location, using the Fermi GBM trigger data, is RA = … [View More]

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[vsnet-grb-info 37612] EP250302a: Optical Observations at CrAO and SAO RAS
by GCN Circulars 05 Mar '25

05 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39596 SUBJECT: EP250302a: Optical Observations at CrAO and SAO RAS DATE: 25/03/05 12:52:41 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Moskvitin (SAO RAS), O. I. Spiridonova (SAO RAS), A. Pozanenko (IKI), E. Klunko (ISTP) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of a fast X-Ray transient EP250302a (Dai et al., GCN 39556; Page et al., GCN 39557) in the R filter … [View More]

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[vsnet-grb-info 37611] GRB 250219A: SVOM/C-GFT optical upper limit at early phase
by GCN Circulars 05 Mar '25

05 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39595 SUBJECT: GRB 250219A: SVOM/C-GFT optical upper limit at early phase DATE: 25/03/05 12:41:57 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Zhe Kang (CHO), F. Daigne (IAP), M. Gnaoui (IAP), Liping Xin(NAOC), Xuhui Han(NAOC), Chao WU (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), Jianyan Wei (NAOC) report on behalf of the SVOM/C-GFT team: We … [View More]

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[vsnet-grb-info 37610] EP 250304A: Optical counterpart detection by LCO
by GCN Circulars 05 Mar '25

05 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39594 SUBJECT: EP 250304A: Optical counterpart detection by LCO DATE: 25/03/05 09:43:20 GMT FROM: ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994(a)gmail.com> Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES), Rahul Gupta (NASA GSFC) on behalf of a larger collaboration. We observed the field of the EP 250304A triggered by the Wide-field X-ray … [View More]

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[vsnet-grb-info 37609] GCN Announcement: End of INTEGRAL Operations
by GCN Announcements 04 Mar '25

04 Mar '25

Beginning March 4, 2025 at 12:08:04 UT, data from the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) will no longer be transmitted to the INTEGRAL Science Data Centre (ISDC), due to the end of scientific operations, more than 22 years after its launch. As a consequence, the INTEGRAL Burst Alert System (IBAS) will be discontinued and GCN Notices will no longer be distributed. The full archive of INTEGRAL GCN Notices is available at https://gcn.gsfc.nasa.gov/integral.html. The IBAS … [View More]

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[vsnet-grb-info 37608] EP250302A: 1.3m DFOT optical afterglow detection
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39593 SUBJECT: EP250302A: 1.3m DFOT optical afterglow detection DATE: 25/03/04 15:36:13 GMT FROM: ANSHIKA GUPTA at ARIES <anshika05180(a)gmail.com> Anshika Gupta, Amit K. Ror, Kuntal Misra, and Shashi B. Pandey (ARIES) report: We observed the field of EP250302A detected by EP-WXT (Trigger ID: 01709132186) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of … [View More]

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[vsnet-grb-info 37607] IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39592 SUBJECT: IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/03/04 14:56:45 GMT FROM: Jessie Thwaites at IceCube/U Wisc-Madison <thwaites(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250302A (https://gcn.nasa.gov/circulars/39549) in a time range of 1000 … [View More]

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[vsnet-grb-info 37606] EP250304a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39591 SUBJECT: EP250304a: refined analysis of the EP-WXT and EP-FXT observations DATE: 25/03/04 14:33:38 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.J. Zhang (THU), C. Y. Dai (NJU), W. Chen, W. X. Wang (NAO, CAS), Y. Liu (NAO, CAS) report on behalf of the Einstein Probe team: The X-ray transient EP250304a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Chen et al., GCN 39580), and followed up by … [View More]several telescopes (Xu et al, GCN 39583, Page et al., GCN 39584, Saccardi et al., GCN 39585, Shilling et al., 39587), with an optical counterpart detected at a redshift of 0.200 (Saccardi et al., GCN 39585). Refined analysis of the WXT data shows that the event started at T0=2025-03-04T01:29:49 (UTC) and lasted for about 1200 s. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a Galactic hydrogen column density of 5 x 10^20 cm^-2 and a photon index of 2.2 (-/+0.1). The derived average unabsorbed 0.5-4 keV flux is 5.3(-/+0.4) x 10^(-10) erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP observed this source autonomously about 200 seconds after T0. On-ground analysis of the FXT data found an uncatalogued source at R.A. = 208.3953, DEC = -42.8050 (J2000) with an uncertainty of about 10 arcsec (radius, 90% C.L. statistical and systematic), which is consistent positionally with the WXT transient. The FXT observation suffered from significant pile up at the begining of the observation. The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a Galactic hydrogen column density of 5 x 10^20 cm^-2 and a photon index of 2.11 (-/+0.05). The derived average unabsorbed 0.5-10 keV flux is 1.75 (-/+0.06) x 10^(-10) erg/s/cm^2 during the time interval from 500 to 1200 seconds after the start of the observation. Further FXT observation started about 4000 seconds after the trigger and showed an average unabsorbed 0.5-10 keV flux of 6.5 (-2.3/+3.5) x 10^(-12) erg/s/cm^2 with an exposure time of about 300 seconds. The uncertainties are at the 90% confidence level for the above parameters. 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/39591. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37605] Konus-Wind detection of GRB 250222A
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39590 SUBJECT: Konus-Wind detection of GRB 250222A DATE: 25/03/04 13:35:08 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 250222A (SVOM-GRM detection: Wang et al., GCN 39454; IPN triangulation: Svinkin et al., GCN 39588) triggered Konus-Wind (KW) at T0=51862.905 s UT (14:24:22.905). The … [View More]

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[vsnet-grb-info 37604] EP250304a: REM NIR upper limits
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39589 SUBJECT: EP250304a: REM NIR upper limits DATE: 25/03/04 13:00:46 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro (INAF-OAB), D. B. Malesani (DAWN/NBI and Radboud), P. D’Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of EP250304a (Chen et al., GCN 39580) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations … [View More]

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[vsnet-grb-info 37603] IPN triangulation of GRB 250222A
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39588 SUBJECT: IPN triangulation of GRB 250222A DATE: 25/03/04 12:59:51 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, Y. Zhang, C. Wang, S. Xiong, J. Wei, and B. Cordier on behalf of the SVOM-GRM team, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns … [View More]

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[vsnet-grb-info 37602] EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39587 SUBJECT: EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve DATE: 25/03/04 12:18:09 GMT FROM: Sam Shilling at Lancaster University <shilling.sam(a)gmail.com> S. P. R. Shilling (Lancaster U.) reports on behalf of the Swift UVOT team: Swift/UVOT observed the field of EP250304a (Chen et al., GCN 39580) for a total of 2 ks in the U-band starting at 02:48:13 UT, 1.25 hours after the detection by Einstein Probe WXT. … [View More]

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[vsnet-grb-info 37601] EP250302a: Mondy Continued Optical Observations
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39586 SUBJECT: EP250302a: Mondy Continued Optical Observations DATE: 25/03/04 10:06:19 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Moskvitin (SAO RAS) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of a fast X-Ray transient EP250302a (Dai et al., GCN 39556; Page et al., GCN 39557) in the R filter with the 1.5-meter telescope of … [View More]

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[vsnet-grb-info 37600] EP250304a: VLT/X-shooter redshift z = 0.200
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39585 SUBJECT: EP250304a: VLT/X-shooter redshift z = 0.200 DATE: 25/03/04 09:54:03 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> A. Saccardi (CEA/Irfu), Z. P. Zhu (NAOC), B. Schneider (LAM), D. Xu (NAOC), L. Izzo (INAF/OAC and DARK/NBI), A. J. Levan (Radboud and Warwick), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), N. R. Tanvir (U. Leicester), S. D. Vergani (CNRS - Paris Observatory/LUX) … [View More]

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[vsnet-grb-info 37599] EP250304a: Swift-XRT detection of a fading X-ray source
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39584 SUBJECT: EP250304a: Swift-XRT detection of a fading X-ray source DATE: 25/03/04 09:18:19 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> K.L. Page, P.A. Evans (U.Leicester) and J. DeLaunay (PSU) report on behalf of the Swift XRT Team: On 2025 March 04 at 02:59 UT, Swift started observing EP250304a, 5.2 ks after the Einstein Probe trigger (GCN Circ. 39580). A fading X-ray source was identified, at a position of RA, Dec = 208.39408, -… [View More]

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[vsnet-grb-info 37598] EP250304a: TRT optical counterpart detection
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39583 SUBJECT: EP250304a: TRT optical counterpart detection DATE: 25/03/04 08:17:49 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> X. Liu, J. An, N.C. Sun (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), S.Q. Jiang, S.Y. Fu, Z.P. Zhu, D. Xu, Z. Fan, W.X. Li, Y.N. Wang (NAOC) report on behalf of a large collaboration: We observed the field of EP250304a (Chen et al, GCN 39580), using the 0.7-m telescope of the Thai Robotic Telescope … [View More]

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[vsnet-grb-info 37597] LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39582 SUBJECT: LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate DATE: 25/03/04 06:58:51 GMT FROM: Pan Guo at KAGRA <panguocas(a)gmail.com> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S250304cb during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo … [View More]Observatory (V1) at 2025-03-04 06:22:45.568 UTC (GPS time: 1425104583.568). The candidate was found by the GstLAL [1] and MBTA [2] analysis pipelines. S250304cb is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.6e-08 Hz, or about one in 6 months. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S250304cb The classification of the GW signal, in order of descending probability, is BBH (96%), Terrestrial (4%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [3] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [3] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 2%. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [4], distributed via GCN notice about 28 seconds after the candidate event time. * bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [4], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 1569 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1768 +/- 541 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] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625 [2] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913 [3] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [4] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/39582. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37596] EP250304a: Global MASTER-Net observations report
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39581 SUBJECT: EP250304a: Global MASTER-Net observations report DATE: 25/03/04 03:00:51 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.… [View More]

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[vsnet-grb-info 37595] EP250304a: Einstein Probe detection of an X-ray transient
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39580 SUBJECT: EP250304a: Einstein Probe detection of an X-ray transient DATE: 25/03/04 02:35:25 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> W. Chen, W. X. Wang (NAO, CAS), Y. J. Zhang (THU), C. Y. Dai (NJU), Y.Liu (NAO, CAS) report on behalf of the Einstein Probe 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 EP250304a. The transient … [View More]

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[vsnet-grb-info 37594] The EP-WXT trigger 01709132212 is not a real source
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39579 SUBJECT: The EP-WXT trigger 01709132212 is not a real source DATE: 25/03/04 02:18:44 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. W. Hu, M. H. Zhang (NAOC, CAS), C. Y. Dai (NJU), Y. Q. Zhao (USTC, PRIC), W. D. Zhang (NAOC, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709132212 at 16:00:13 UTC on 3th March 2025, is not a real source. View this GCN Circular online at https://gcn.nasa.gov/circulars/39579. --- To … [View More]

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[vsnet-grb-info 37593] EP250302a: SVOM/VT optical observation
by GCN Circulars 04 Mar '25

04 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39578 SUBJECT: EP250302a: SVOM/VT optical observation DATE: 25/03/04 02:15:58 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu, D. H. Zhao, Y. N. Ma, L. P. Xin, Y. L. Qiu, H. L. Li, Z. H. Yao, Y. Xu, P. P. Zhang, W. J. Xie, J. Wang, X. H. Han, Y. J. Xiao, H. B. Cai, J. Y. Wei(NAOC), J. T. Palmerio(CEA/Irfu) report on behalf of the SVOM team: The SVOM/VT conducted a ToO follow-up observations of the EP250302a (Zhu et al., GCN 39550) in VT_B … [View More]

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[vsnet-grb-info 37592] LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39577 SUBJECT: LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits DATE: 25/03/03 19:55:29 GMT FROM: noelklin(a)umbc.edu Noel Klingler (NASA-GSFC / UMBC / CRESST II), Sam Shilling (Lancaster U.), P.A. Evans (U. Leicester), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), S.B. Cenko (NASA/GSFC), R.A.J. Eyles-Ferris (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld … [View More]

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[vsnet-grb-info 37591] EP250302a: SAO RAS optical observations
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39576 SUBJECT: EP250302a: SAO RAS optical observations DATE: 25/03/03 16:32:59 GMT FROM: Moskvitin Alexander at SAO RAS <mosk(a)sao.ru> A. S. Moskvitin, O. A. Maslennikova (SAO RAS), A. Pozanenko (IKI) and N. Pankov (HSE, IKI) report on behalf of larger collaboration. We observed the field of the X-ray transient EP250302a (Dai et al., GCN 39556; Page et al., GCN 39557) with SAO RAS 1-m telescope Zeiss-1000 equipped with CCD-photometer under … [View More]

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[vsnet-grb-info 37590] EP250302a : GIT optical follow-up
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39575 SUBJECT: EP250302a : GIT optical follow-up DATE: 25/03/03 16:09:43 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> D. Eappachen (IIA), V. Swain (IITB), A.P. Saikia (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team: We observed the field of EP250302a (Dai et al., GCN 39556) with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2025-03-02 20:51:47 UT, … [View More]

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[vsnet-grb-info 37589] EP250302a: VLT/X-shooter redshift confirmation
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39574 SUBJECT: EP250302a: VLT/X-shooter redshift confirmation DATE: 25/03/03 15:53:51 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata <yyang(a)roma2.infn.it> Yu-Han Yang (U Rome), Eleonora Troja (U Rome), and Rosa Becerra (U Rome) report on behalf of the ERC BHianca team: A further analysis was performed on the VLT/X-shooter spectrum reported by Yang et al. (GCN 39561). Whereas no significant features are visible in the VIS and NIR arms, we … [View More]

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[vsnet-grb-info 37588] EP250225a: the candidate optical counterpart is an AGN
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39573 SUBJECT: EP250225a: the candidate optical counterpart is an AGN DATE: 25/03/03 15:25:46 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> D. B. Malesani (DAWN/NBI and Radboud Univ.), D. Mata-Sanchez (IAC and ULL), A. Martin-Carrillo (UCD), A. J. Levan (Radboud Univ.), P. G. Jonker (Radboud Univ.), report on behalf of a larger collaboration: We observed again the variable object (Malesani et al., GCN 39516) … [View More]

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[vsnet-grb-info 37587] EP250302a: Kinder optical follow-up observations
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39572 SUBJECT: EP250302a: Kinder optical follow-up observations DATE: 25/03/03 14:21:48 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> A. Aryan, T.-W. Chen, C.-S. Lin (all NCU), A. K. H. Kong (NTHU), J. Gillanders (Oxford), S. J. Smartt (Oxford/QUB), Y. J. Yang, A. Sankar. K, Y.-C. Pan, C.-C. Ngeow, W.-J. Hou, M.-H. Lee, H.-C. Lin, C.-H. Lai, H.-Y. Hsiao, J.-K. Guo (all NCU), S. Yang, L. … [View More]L. Fan, Z. N. Wang, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP250302a (Zhu et al., GCN 39550; Dai et al., GCN 39556) using the 40cm SLT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al. 2024, arXiv:2406.09270). The first SLT epoch of observations in the r band started at 18:30 UT on the 2nd of March 2025 (MJD = 60736.771), ~2.91 hrs after the EP trigger. We took a total of 12 frames in r-band spanning a period of about 2.91hr to 5.22hr since the EP-WXT trigger. The optical counterpart candidate proposed by Zhu et al., (GCN 39550 ) and confirmed by several other observations (Busmann et al., GCN 39551; Leonini et al., GCN 39553; Wu et al., GCN 39555; Xin et al., GCN 39558; Adami et al., GCN 39560; Yang et al., GCN 39561; Becerra et al., GCN 39562; and Izzo et al., GCN 39564), was clearly detected in almost each of the individual frame (besides the last frame). We utilized the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform PSF photometry on individual frames. The details of the observation and measured photometry from the first frame (in the AB system) were as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | Seeing | Airmass SLT | r | 60736.771 | 2.91 | 300 * 1 | 19.60 +/- 0.05 | 1".25 | 1.14 The presented magnitude was calibrated using the field stars from the Pan-STARRS1 catalog and was not corrected for the expected Galactic foreground extinction corresponding to a reddening of A_r = 0.06 mag, respectively, in the direction of the transient (Schlafly & Finkbeiner 2011). View this GCN Circular online at https://gcn.nasa.gov/circulars/39572. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37586] LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39571 SUBJECT: LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search DATE: 25/03/03 13:51:37 GMT FROM: Zsuzsa Marka at IceCube/Columbia University <zsuzsa(a)astro.columbia.edu> IceCube Collaboration (http://icecube.wisc.edu/) reports: We have performed a search for track-like muon neutrino candidate events detected by IceCube consistent with the sky localization of the low-significance gravitational-wave … [View More]candidate event S250302av in a time range of 1000 seconds centered on the alert event time (2025-03-02 13:57:15 UTC to 2025-03-02 14:13:55 UTC) [1,2]. During this time period, IceCube was collecting good quality data. A single hypothesis test was conducted using a Bayesian approach to quantify the joint GW + neutrino event significance, which assumes a binary merger scenario and accounts for known astrophysical priors, such as GW source distance, in the statistical significance estimation [3]. Two track-like events were found in spatial and temporal coincidence with the gravitational-wave candidate S250302av calculated from the map circulated in the S250302av-2-Preliminary notice. This represents an overall p-value of 0.0084 for the Bayesian search. The p-value measures the consistency of the observed track-like events with the known atmospheric backgrounds for this single map (not accounting for statistical trials from multiple GW events). Further details are available at https://gcn.nasa.gov/missions/icecube and at https://roc.icecube.wisc.edu/public/LvkNuTrackSearch. Properties of the coincident event are shown below: dt(s) RA(deg) Dec(deg) Angular uncertainty(deg) p-value(Bayesian) ------------------------------------------------------------------------------------- 76.86 114.87 3.25 1.16 0.0298 211.98 191.11 58.45 5.39 0.0137 where: dt = Time of track event minus time of GW trigger (sec) Angular uncertainty = Angular uncertainty of track event: the radius of a circle representing 90% CL containment by area. p-value = the individual p-value for the specific track event from this search. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu [1] M. G. Aartsen et al 2020 ApJL 898 L10 [2] Abbasi et al. Astrophys.J. 944 (2023) 1, 80 [3] I. Bartos et al. 2019 Phys. Rev. D 100, 083017 View this GCN Circular online at https://gcn.nasa.gov/circulars/39571. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37585] EP250302a: Swift/UVOT detection
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39570 SUBJECT: EP250302a: Swift/UVOT detection DATE: 25/03/03 12:58:05 GMT FROM: Sam Shilling at Lancaster University <shilling.sam(a)gmail.com> S. P. R. Shilling (Lancaster U.) and A. A. Breeveld (UCL-MSSL) reports on behalf of the Swift UVOT team: Swift/UVOT observed the field of EP250302a (Dai et al., GCN 39556) for 1029 seconds in the U-band starting at 16:36:56 UT, 1 hour after the detection by Einstein Probe WXT. A source consistent with … [View More]

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[vsnet-grb-info 37584] EP250302a: NUTTelA-TAO Early Measurments
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39569 SUBJECT: EP250302a: NUTTelA-TAO Early Measurments DATE: 25/03/03 12:18:23 GMT FROM: Toktarkhan Komesh at Nazarbayev University <toktarkhan.komesh(a)nu.edu.kz> T. Komesh (NU), Z. Abdullayev (NU), Z. Maksut (NU), D. Berdikhan (NU), B. Grossan (UCB, NU), M. Krugov (FAI) and E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory: The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) … [View More]pointed at EP250302a on receipt of an automated GCN / EP position alert, observing in Sloan g' and r' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14). We started observations at 15:42:43 UT on 2025-03-02, 399 seconds after the Einstein Probe trigger (Dai et al., GCN 39556). Observations were made in partially cloudy conditions. A new and changing source consistent with the XRT position (Page et al., GCN 38761) was detected. We report the following photometric values for the optical transient: tc-t0(s) g'(mag) err r'(mag) err exposure_time (s) -------------------------------------------------------------- 424 - 18.36 0.08 50 628 - 18.35 0.08 300 928 - 18.80 0.13 300 1273 - 18.76 0.07 240 1513 - 18.55 0.06 240 1753 - 18.12 0.04 240 1993 - 17.71 0.03 240 2233 - 17.58 0.02 240 2686 - 17.48 0.03 240 2926 - 17.54 0.02 240 3166 - 17.58 0.02 240 3406 - 17.65 0.02 240 3646 - 17.68 0.03 240 3886 - 17.73 0.03 240 4126 - 17.85 0.03 240 4366 - 17.88 0.04 240 4606 - 17.95 0.03 240 4846 - 18.08 0.04 240 5086 - 18.11 0.03 240 5326 - 18.18 0.04 240 5566 - 18.32 0.04 240 5806 - 18.47 0.04 240 6046 - 18.56 0.04 240 6348 18.93 0.05 18.56 0.04 240 6588 18.99 0.06 18.76 0.04 240 6828 19.01 0.05 18.86 0.05 240 7068 19.05 0.05 18.86 0.05 240 7308 19.06 0.05 18.90 0.05 240 7548 19.12 0.05 18.94 0.05 240 7788 19.28 0.07 19.01 0.06 240 8028 19.43 0.08 19.01 0.06 240 8269 19.53 0.08 19.19 0.07 240 8509 19.34 0.06 19.19 0.06 240 tc-t0 = trigger time minus image center time. Calibration was done with 4 bright Pan-STARRS catalog stars on our images. Our results are in agreement with those reported in previously published circulars (Zhu et. al, GCN 39550; Wu et. al, GCN 39555; Xin et. al, GCN 39558; Pankov et al., GCN 39565). We caution the reader that these are preliminary results, without color or other corrections, and will likely change in small measure. Please also note that times are approximate. ---------------------------------- NU = Nazarbayev University, Astana, Kazakhstan UCB = University of California, Berkeley, USA FAI = Fesenkov Astrophysical Institute, Kazakhstan This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP26103591). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan. View this GCN Circular online at https://gcn.nasa.gov/circulars/39569. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37583] EP250302a: optical observation from the INAF Asiago Observatory
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39568 SUBJECT: EP250302a: optical observation from the INAF Asiago Observatory DATE: 25/03/03 11:27:12 GMT FROM: Andrea Reguitti at INAF - Osservatorio Astronomico di Brera <andreareguitti(a)gmail.com> A. Reguitti (INAF-OAB) reports on behalf of the CIBO (Coordinamento Italiano Burst Ottici) collaboration: We observed the field of EP250302a (Zhu et al., GCN 39550) from the INAF - Padova Astronomical Observatory located in Asiago (Italy) with the 67/… [View More]

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[vsnet-grb-info 37582] EP250302a: REM NIR upper limits
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39567 SUBJECT: EP250302a: REM NIR upper limits DATE: 25/03/03 10:11:26 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of EP250302a (Dai et al., GCN 39556) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the J, H, and K bands, started on … [View More]

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[vsnet-grb-info 37581] IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39566 SUBJECT: IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect DATE: 25/03/03 09:56:46 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> K. Labzina, K.Zhirkov, V.Lipunov, E.Gorbovskoy, G.Antipov, D.Vlasenko, A.Kuznetsov, N.Tyurina, P.Balanutsa, A.Chasovnikov, D.Kuvshinov, V.Topolev,Ya.Kechin,Yu.Tselik, K.Minkina(Lomonosov Moscow State University, SAI, Physics Department), O.Gress, N.Budnev, … [View More]O.Ershova (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), D.Buckley (SAAO), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), 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 IceCube-241113 (IceCube, Zegarelli et al. GCN#38200) to the IceCube Alert 241113.02 (trigger No 30891383, 13h 04m 46.32s , +08d 29m 27.6s, R=0.53) errorbox 477 sec after notice time and 554 sec after trigger time at 2024-11-13 00:31:35 UT, with upper limit up to 16.0 mag. (Lipunov et al. GCN#38186) MASTER cover map: https://master.sai.msu.ru/site/master2/observ.php?id=2668204 We analyzed MASTER archive images since 2012 of the sources, that can be related with this event. We detected blazar J131155.76+085340.9 inside 3 sigma https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=… and we detected its brightening up to 16.9m during last nights observations. The MASTER archive light curve from 2010 year is available at http://observ.pereplet.ru/MASTER_IC241113A.jpg Light curve shows that after neutrino alert the blazar J131155.76+085340.9 was in a dim state 20.2m, after which, within an half hour, it increased its brightness to 16.9m. This, we report observation of an Zhirkov effect, discovered earlier (The Astrophysic Jornal Letters, 896, L19, 2020 https://ui.adsabs.harvard.edu/abs/2020ApJ...896L..19L/abstract ). View this GCN Circular online at https://gcn.nasa.gov/circulars/39566. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37580] EP250302a: Mondy Observations and Optical Light Curve
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39565 SUBJECT: EP250302a: Mondy Observations and Optical Light Curve DATE: 25/03/03 09:54:00 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), A. Moskvitin (SAO RAS), E. Klunko (ISTP) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of a fast X-Ray transient EP250302a (Zhu et. al, GCN 39550; Busmann et. al, GCN 39551; Leonini et. al, GCN 39553; Wu et. al, GCN … [View More]

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[vsnet-grb-info 37579] EP250302a: VLT/MUSE optical redshift z = 1.131
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39564 SUBJECT: EP250302a: VLT/MUSE optical redshift z = 1.131 DATE: 25/03/03 09:11:58 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> L. Izzo (INAF/OACn and DARK/NBI), R. A. J. Eyles-Ferris (Univ. Leicester), D. Xu (NAOC), A. Saccardi (CEA/Irfu), B. Schneider (LAM), D. B. Malesani (DAWN/NBI and Radboud Univ.), J. T. Palmerio (CEA/Irfu), N. R. Tanvir (Univ. Leicester), P. G. Jonker (Radboud Univ.), S. D. Vergani (… [View More]CNRS - Paris Observatory/LUX), A. J. Levan (Radboud Univ. and Warwick Univ.), report on behalf of the Stargate collaboration: We observed the optical/NIR counterpart (Zhu et al., GCN 39550; Busmann et al., GCN 39551; Leonini et al., GCN 39553; Wu et al., GCN 39555; Xin et al., GCN 39558; Adami et al., GCN 39560; Becerra et al., GCN 39562) of the fast X-ray transient EP250302a (Dai et al., GCN 39556) using the ESO VLT UT4 (Yepun) equipped with the MUSE integral-field spectrograph. The observation mid-epoch is 2025 March 3.193 UT (13.03 hr after the initial high-energy trigger), the total exposure time is 76.5 min, and the covered wavelength range is 4750-9300 AA. The optical counterpart (Zhu et al., GCN 39550) is well detected in the wavelength-stacked “white light” image, as well as in continuum spectroscopy. We also observe several clear absorption features, which we interpret as due to Mg I (2853), Mg II (2804, 2796), and Fe II (2600, 2587, 2383, 2374, 2344), all at a common redshift z = 1.131. Given the overall good S/N of the spectrum, and the fact that there are no features left un-identified, we consider z = 1.131 to be most likely the redshift of EP250302a. Our spectra do not cover the blue region where the z = 0.549 features reported by Yang et al. (GCN 39561) would fall, so we cannot confirm the presence of that system, which could be an intervening absorber. No emission lines at z = 0.549 appear in our data. Thanks to the large MUSE field of view (1' x 1'), further to the optical transient, two neighboring bright galaxies were covered in our observation, including the one noted by Busmann et al. (GCN 39551) and Yang et al. (GCN 39561). For them, we measure the following redshifts: 1) RA = 11:18:05.26, Dec = +33:35:05.6: z = 0.127 from Na I D, Mg b, Hbeta, G band absorption; 2) RA = 11:18:01.03, Dec = +33:35:30.8: z = 0.127 from Halpha, [N II] and [S II] emission. We conclude that these objects are not physically associated with EP250302a. We thank Malte Busmann and Brendan O’Connor for sharing a finding chart of the field, and the ESO observing staff in Paranal, in particular Claudia Cid, Monika Petr-Gotzens, and Jonathan Smoker, for efficiently carrying out these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39564. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37578] INTEGRAL: end of scientific operations
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39563 SUBJECT: INTEGRAL: end of scientific operations DATE: 25/03/03 08:52:32 GMT FROM: Carlo Ferrigno <carlo.ferrigno(a)unige.ch> From 2025-03-04 at 12:08:04 UT, data from the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) will not be transmitted anymore to the INTEGRAL science data centre (ISDC) owing to the end of scientific operations, more than 22 years after its launch. As a consequence, the INTEGRAL Burst Alert System (IBAS) will … [View More]

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[vsnet-grb-info 37577] EP250302A: VLT near-infrared observations
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39562 SUBJECT: EP250302A: VLT near-infrared observations DATE: 25/03/03 08:26:32 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa Becerra (U Rome), Yu-Han Yang (U Rome), Muskan Yadav (U Rome), Eleonora Troja (U Rome) report on behalf of the ERC BHianca team: We observed the field of EP250302A (Dai et al., GCN 39556) with the HAWKI imager on the ESO VLT UT4 (Yepun). Observations began at T+14.1 h days and were carried … [View More]

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[vsnet-grb-info 37576] EP250302A: VLT/X-shooter tentative redshift
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39561 SUBJECT: EP250302A: VLT/X-shooter tentative redshift DATE: 25/03/03 08:21:14 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Yu-Han Yang (U Rome), Eleonora Troja (U Rome), and Rosa Becerra (U Rome) report on behalf of the ERC BHianca team: We observed the field of EP250302A (Dai et al., GCN 39556) with the X-Shooter spectrograph on the ESO VLT UT3 (Melipal). Observations began at T+13.6 hours and obtained a total … [View More]

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[vsnet-grb-info 37575] EP250302A: VLT/X-shooter tentative redshift
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39561 SUBJECT: EP250302A: VLT/X-shooter tentative redshift DATE: 25/03/03 08:21:14 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Yu-Han Yang (U Rome), Eleonora Troja (U Rome), and Rosa Becerra (U Rome) report on behalf of the ERC BHianca team: We observed the field of EP250302A (Dai et al., GCN 39556) with the X-Shooter spectrograph on the ESO VLT UT3 (Melipal). Observations began at T+13.6 hours and obtained a total … [View More]

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[vsnet-grb-info 37574] EP250302a: OHP/T193 optical and spectroscopic observations
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39560 SUBJECT: EP250302a: OHP/T193 optical and spectroscopic observations DATE: 25/03/03 08:13:10 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), S. Basa (LAM/OHP/Pytheas/AMU), M. Dennefeld (IAP/CNRS/Sorbonne U.), E. Le Floc'h (CEA/Irfu), J. P. Palmerio (CEA/Irfu), A. Saccardi (CEA/Irfu), J. Schmitt (OHP/Pytheas/AMU), F. Schüssler (CEA/DPhP), D. Turpin (CEA/Irfu), S. D. Vergani (CNRS, Paris Obs./… [View More]

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[vsnet-grb-info 37573] EP250302a: Global MASTER-Net observations report
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39559 SUBJECT: EP250302a: Global MASTER-Net observations report DATE: 25/03/03 08:09:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.… [View More]

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[vsnet-grb-info 37572] EP250302a: Xinglong F60B optical observation
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39558 SUBJECT: EP250302a: Xinglong F60B optical observation DATE: 25/03/03 07:52:34 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> L. P. Xin, X. H. Han, P. P. Zhang, J. Wang, C. Wu, Y. L. Qiu, H. B. Cai, H. L. Li, X. M. Lu, R. S. Zhang, Y. J. Xiao, J. S. Deng, Z. H. Yao, Y. N. Ma, J. Y. Wei (NAOC), X. G. Wang, E. W. Liang (GXU) report: We observed location of EP250302a (Trigger ID: 01709132186, Dai et al., GCN 39556) with F60B telescope in R … [View More]

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[vsnet-grb-info 37571] EP250302a: Swift-XRT observations of a fading X-ray source
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39557 SUBJECT: EP250302a: Swift-XRT observations of a fading X-ray source DATE: 25/03/03 07:43:50 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> K.L. Page, P.A. Evans (U.Leicester) and J. DeLaunay (PSU) report on behalf of the Swift XRT Team: On 2025 March 02 at 16:36 UT, Swift started observing EP250302a, 3.6 ks after the trigger (GCN Circ. 39556). A fading X-ray source was identified, at a position of RA, Dec = 169.51508, +33.5858, … [View More]

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[vsnet-grb-info 37570] EP250302a: Einstein Probe detection of an X-ray transient
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39556 SUBJECT: EP250302a: Einstein Probe detection of an X-ray transient DATE: 25/03/03 07:23:40 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> C. Y. Dai (NJU), Y.Q. Zhao (USTC, PRIC), X. Mao, S. X. Wen, W. Yuan (NAO, CAS) report on behalf of the Einstein Probe 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 EP250302a. The transient triggered … [View More]

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[vsnet-grb-info 37569] EP250302a: SVOM/C-GFT optical observations
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39555 SUBJECT: EP250302a: SVOM/C-GFT optical observations DATE: 25/03/03 05:21:19 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), Jianyan Wei (NAOC) report on behalf of the SVOM/C-GFT team: We observed the field of EP250302a detected by … [View More]

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[vsnet-grb-info 37568] GRB250226A: GRANDMA Optical Observations
by GCN Circulars 03 Mar '25

03 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39554 SUBJECT: GRB250226A: GRANDMA Optical Observations DATE: 25/03/03 04:48:59 GMT FROM: Lydia Nyambane at UMN <nyamb021(a)umn.edu> M. Tanasan (NARIT), L. Nyambane (UMN), H. Muenter (UMN), C. Andrade (UMN), Y. Rajabov (UBAI), F. Magnani (CPPM), M. Masek (FZU), S. Alshamsi (AUS), W. Corradi (LNA), T. Almeida (LNA), K. Noysena (NARIT), L. Fraga (LNA), N. Sasaki (LNA), A. Takey (NRIAG), Y. Hendy (NRIAG), M. Abdelkareem (NRIAG), E. Elhosseiny F. … [View More]Navarete (NOIRLab/SOAR), S. Antier (OCA/IJCLAB), M. Coughlin (UMN), S. Karpov (FZU), P. Hello (IJCLAB), P-A. Duverne (APC), T. Pradier (Unistra/IPHC), N. Guessoum (AUS) on behalf of the GRANDMA and Kilonova-Catcher collaborations: The GRANDMA collaboration imaged the field of a fast X-ray transient GRB 250226A discovered by Fermi GBM (Fermi GBM team, GCN circ. 39479) and EP WXT and FXT (Jiang et al., GCN circ. 39482; Jiang et al., GCN circ. 39513) and detected also by GECAM-B (Zhang et al., GCN circ. 39492) and INTEGRAL SPI-ACS and PICsIT (Thakur et al., GCN circ. 39518). GRANDMA observations were performed at RA = 224.2651, DEC = 20.9756 with the OPD/60cm, TRT-SBO, KAO, Lisnyky/AZT-8 and AbAO-T70 telescopes starting ~0.4 days post T0 in the R and i' bands. We detect the optical afterglow and report some of the observations at the following magnitudes: | T-start (UTC) | Magnitude | UL (5sigma) | Filter | Telescope | | 2025-02-26 17:19:21 | 21.5 +/- 0.2 | 21.5 | R (AB) | TRT-SBO | | 2025-02-27 01:39:46 | 21.15+/-0.15 | 22.6 | i’ (AB) | KAO | | 2025-02-27 05:28:50 | 22.0+/-0.25 | 21.8 | R (AB) | OPD/60cm | Our findings were consistent with the MEPHISTO telescope (Zou et al., GCN 39511), the Xinglong Observatory ( Jiang et al., GCN 39515), and the Las Cumbres Observatory Global Telescope network (LCOGT) (Poidevin et al., GCN 39524). All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained in Johnson Cousin filters were calibrated using the Gaia DR3 and PS1 catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/). View this GCN Circular online at https://gcn.nasa.gov/circulars/39554. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37567] EP250302a: Montarrenti Observatory optical detection
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39553 SUBJECT: EP250302a: Montarrenti Observatory optical detection DATE: 25/03/02 23:05:33 GMT FROM: Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini(a)iol.it> S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy) and K. Kalinowski (Aarhus University, … [View More]

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[vsnet-grb-info 37566] Fermi GRB 250302A: Global MASTER-Net observations report
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39552 SUBJECT: Fermi GRB 250302A: Global MASTER-Net observations report DATE: 25/03/02 21:33:42 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta,… [View More] R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), 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 GRB 250302A ( Fermi GBM team, GCN 39548) errorbox 21539 sec after notice time and 21575 sec after trigger time at 2025-03-02 19:46:08 UT, with upper limit up to 20.4 mag. The observations began at zenith distance = 43 deg. The sun altitude is -36.5 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250302A errorbox 22677 sec after notice time and 22713 sec after trigger time at 2025-03-02 20:05:06 UT, with upper limit up to 17.7 mag. The observations began at zenith distance = 77 deg. The sun altitude is -50.2 deg. The galactic latitude b = 46 deg., longitude l = 22 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2796892 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 21605 | 2025-03-02 19:46:08 | MASTER-Tunka | (15h 31m 17.49s , +16d 30m 25.9s) | C | 60 | 19.8 | 21665 | 2025-03-02 19:46:08 | MASTER-Tunka | (15h 31m 17.49s , +16d 30m 25.9s) | C | 180 | 20.3 | Coadd 21678 | 2025-03-02 19:47:20 | MASTER-Tunka | (15h 39m 40.44s , +16d 31m 15.0s) | C | 60 | 19.8 | 21738 | 2025-03-02 19:47:20 | MASTER-Tunka | (15h 39m 40.44s , +16d 31m 14.9s) | C | 180 | 20.3 | Coadd 22064 | 2025-03-02 19:53:47 | MASTER-Tunka | (15h 41m 02.12s , +18d 25m 27.9s) | C | 60 | 19.8 | 22124 | 2025-03-02 19:53:47 | MASTER-Tunka | (15h 41m 02.11s , +18d 25m 27.9s) | C | 180 | 20.4 | Coadd 22137 | 2025-03-02 19:55:00 | MASTER-Tunka | (15h 49m 28.20s , +18d 23m 04.7s) | C | 60 | 19.7 | 22197 | 2025-03-02 19:55:00 | MASTER-Tunka | (15h 49m 28.20s , +18d 23m 04.6s) | C | 180 | 20.3 | Coadd 22210 | 2025-03-02 19:56:13 | MASTER-Tunka | (15h 31m 19.81s , +16d 32m 30.0s) | C | 60 | 19.9 | 22283 | 2025-03-02 19:57:25 | MASTER-Tunka | (15h 39m 34.02s , +16d 30m 56.3s) | C | 60 | 19.9 | 22586 | 2025-03-02 20:02:28 | MASTER-Tunka | (15h 23m 46.12s , +16d 31m 47.0s) | C | 60 | 20.0 | 22646 | 2025-03-02 20:02:28 | MASTER-Tunka | (15h 23m 46.12s , +16d 31m 47.0s) | C | 180 | 20.3 | Coadd 22744 | 2025-03-02 20:05:06 | MASTER-Kislovodsk | (15h 31m 05.90s , +18d 24m 03.2s) | C | 60 | 13.6 | 22820 | 2025-03-02 20:06:23 | MASTER-Tunka | (15h 40m 59.24s , +18d 26m 16.1s) | C | 60 | 19.8 | 22823 | 2025-03-02 20:06:26 | MASTER-Kislovodsk | (15h 20m 24.78s , +14d 35m 08.1s) | C | 60 | 14.4 | 22893 | 2025-03-02 20:07:36 | MASTER-Tunka | (15h 49m 30.08s , +18d 24m 37.9s) | C | 60 | 19.8 | 22904 | 2025-03-02 20:07:46 | MASTER-Kislovodsk | (15h 28m 43.31s , +14d 36m 18.2s) | C | 60 | 13.6 | 22967 | 2025-03-02 20:08:49 | MASTER-Tunka | (15h 31m 14.39s , +16d 31m 14.0s) | C | 60 | 19.8 | 23042 | 2025-03-02 20:10:04 | MASTER-Tunka | (15h 39m 39.86s , +16d 31m 01.5s) | C | 60 | 19.7 | 23160 | 2025-03-02 20:12:03 | MASTER-Kislovodsk | (15h 36m 12.34s , +14d 34m 34.1s) | C | 60 | 15.6 | 23240 | 2025-03-02 20:13:23 | MASTER-Kislovodsk | (15h 44m 23.73s , +14d 35m 43.7s) | C | 60 | 14.7 | 23337 | 2025-03-02 20:14:59 | MASTER-Tunka | (15h 23m 42.86s , +16d 33m 11.8s) | C | 60 | 19.9 | 23413 | 2025-03-02 20:16:15 | MASTER-Tunka | (15h 30m 58.44s , +12d 44m 41.7s) | C | 60 | 19.8 | 23473 | 2025-03-02 20:16:15 | MASTER-Tunka | (15h 30m 58.44s , +12d 44m 41.7s) | C | 180 | 20.1 | Coadd 23480 | 2025-03-02 20:17:22 | MASTER-Kislovodsk | (15h 31m 02.91s , +18d 23m 56.7s) | C | 60 | 16.9 | 23486 | 2025-03-02 20:17:29 | MASTER-Tunka | (15h 39m 05.45s , +12d 43m 05.6s) | C | 60 | 19.7 | 23546 | 2025-03-02 20:17:29 | MASTER-Tunka | (15h 39m 05.45s , +12d 43m 05.5s) | C | 180 | 20.1 | Coadd 23560 | 2025-03-02 20:18:42 | MASTER-Kislovodsk | (15h 20m 23.76s , +14d 37m 26.2s) | C | 60 | 17.0 | 23561 | 2025-03-02 20:18:43 | MASTER-Tunka | (15h 41m 05.86s , +18d 25m 13.1s) | C | 60 | 19.8 | 23637 | 2025-03-02 20:19:59 | MASTER-Tunka | (15h 49m 27.79s , +18d 25m 54.4s) | C | 60 | 19.7 | 23639 | 2025-03-02 20:20:02 | MASTER-Kislovodsk | (15h 28m 43.11s , +14d 36m 08.7s) | C | 60 | 16.8 | 23712 | 2025-03-02 20:21:15 | MASTER-Tunka | (15h 31m 16.75s , +16d 31m 55.3s) | C | 60 | 19.9 | 23772 | 2025-03-02 20:21:15 | MASTER-Tunka | (15h 31m 16.75s , +16d 31m 55.1s) | C | 180 | 19.8 | Coadd 23785 | 2025-03-02 20:22:27 | MASTER-Tunka | (15h 39m 40.80s , +16d 32m 51.7s) | C | 60 | 19.8 | 23799 | 2025-03-02 20:22:42 | MASTER-Kislovodsk | (15h 21m 17.81s , +12d 41m 36.6s) | C | 60 | 17.1 | 23959 | 2025-03-02 20:25:22 | MASTER-Kislovodsk | (15h 36m 07.19s , +14d 35m 28.8s) | C | 60 | 17.1 | 24039 | 2025-03-02 20:26:41 | MASTER-Kislovodsk | (15h 44m 26.50s , +14d 36m 37.5s) | C | 60 | 17.0 | 24080 | 2025-03-02 20:27:23 | MASTER-Tunka | (15h 23m 42.84s , +16d 32m 51.8s) | C | 60 | 19.9 | 24154 | 2025-03-02 20:28:37 | MASTER-Tunka | (15h 30m 58.25s , +12d 44m 31.8s) | C | 60 | 19.7 | 24230 | 2025-03-02 20:29:53 | MASTER-Tunka | (15h 39m 07.48s , +12d 45m 31.1s) | C | 60 | 19.7 | 24278 | 2025-03-02 20:30:40 | MASTER-Kislovodsk | (15h 31m 07.61s , +18d 24m 25.8s) | C | 60 | 17.4 | 24305 | 2025-03-02 20:31:07 | MASTER-Tunka | (15h 41m 01.62s , +18d 25m 42.8s) | C | 60 | 19.8 | 24365 | 2025-03-02 20:31:07 | MASTER-Tunka | (15h 41m 01.62s , +18d 25m 42.8s) | C | 180 | 20.2 | Coadd 24749 | 2025-03-02 20:38:31 | MASTER-Tunka | (15h 30m 53.25s , +16d 35m 14.6s) | C | 60 | 19.9 | 24939 | 2025-03-02 20:41:41 | MASTER-Kislovodsk | (15h 21m 11.94s , +12d 41m 22.0s) | C | 60 | 17.7 | 25098 | 2025-03-02 20:44:21 | MASTER-Kislovodsk | (15h 36m 07.54s , +14d 36m 59.1s) | C | 60 | 17.5 | 25178 | 2025-03-02 20:45:41 | MASTER-Kislovodsk | (15h 44m 23.92s , +14d 35m 10.2s) | C | 60 | 17.4 | 25423 | 2025-03-02 20:49:46 | MASTER-Tunka | (15h 23m 44.45s , +16d 35m 47.7s) | C | 60 | 20.0 | 25497 | 2025-03-02 20:50:59 | MASTER-Tunka | (15h 30m 54.18s , +12d 45m 40.7s) | C | 60 | 19.9 | 25569 | 2025-03-02 20:52:11 | MASTER-Tunka | (15h 39m 10.58s , +12d 46m 23.3s) | C | 60 | 19.8 | 25643 | 2025-03-02 20:53:25 | MASTER-Tunka | (15h 40m 57.76s , +18d 27m 42.0s) | C | 60 | 20.0 | 25715 | 2025-03-02 20:54:38 | MASTER-Tunka | (15h 49m 22.96s , +18d 28m 04.2s) | C | 60 | 19.8 | 25788 | 2025-03-02 20:55:51 | MASTER-Tunka | (15h 31m 18.68s , +16d 34m 38.3s) | C | 60 | 19.8 | 25861 | 2025-03-02 20:57:04 | MASTER-Tunka | (15h 39m 32.28s , +16d 33m 01.3s) | C | 60 | 19.8 | 26164 | 2025-03-02 21:02:06 | MASTER-Tunka | (15h 23m 47.97s , +16d 36m 20.0s) | C | 60 | 19.7 | 26237 | 2025-03-02 21:03:20 | MASTER-Tunka | (15h 30m 50.25s , +12d 47m 05.1s) | C | 60 | 19.6 | 26311 | 2025-03-02 21:04:33 | MASTER-Tunka | (15h 39m 02.80s , +12d 47m 29.2s) | C | 60 | 19.5 | 26385 | 2025-03-02 21:05:48 | MASTER-Tunka | (15h 41m 03.56s , +18d 28m 19.9s) | C | 60 | 18.6 | 26460 | 2025-03-02 21:07:03 | MASTER-Tunka | (15h 46m 29.50s , +12d 46m 38.1s) | C | 60 | 19.8 | 26537 | 2025-03-02 21:08:19 | MASTER-Tunka | (15h 54m 41.53s , +12d 44m 47.4s) | C | 60 | 19.8 | 26838 | 2025-03-02 21:13:21 | MASTER-Tunka | (15h 23m 46.02s , +16d 36m 09.2s) | C | 60 | 20.1 | 26914 | 2025-03-02 21:14:37 | MASTER-Tunka | (15h 30m 49.86s , +12d 46m 41.0s) | C | 60 | 20.0 | 27078 | 2025-03-02 21:17:20 | MASTER-Tunka | (15h 39m 08.10s , +12d 47m 46.3s) | C | 60 | 20.0 | 27150 | 2025-03-02 21:18:33 | MASTER-Tunka | (15h 46m 26.15s , +12d 46m 38.9s) | C | 60 | 20.0 | 27222 | 2025-03-02 21:19:44 | MASTER-Tunka | (15h 54m 37.57s , +12d 47m 02.5s) | C | 60 | 20.0 | 27300 | 2025-03-02 21:21:02 | MASTER-Tunka | (15h 38m 21.62s , +14d 40m 25.5s) | C | 60 | 20.1 | 27373 | 2025-03-02 21:22:15 | MASTER-Tunka | (15h 46m 43.50s , +14d 39m 54.8s) | C | 60 | 20.1 | 27442 | 2025-03-02 21:23:24 | MASTER-Tunka | (15h 55m 28.03s , +10d 51m 13.2s) | C | 60 | 20.0 | 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/39552. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37565] EP250302a: FTW optical and NIR detection
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39551 SUBJECT: EP250302a: FTW optical and NIR detection DATE: 25/03/02 20:56:16 GMT FROM: Brendan O'Connor at Carnegie Mellon University <boconno2(a)andrew.cmu.edu> Malte Busmann (LMU), Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU) and Antonella Palmese (Carnegie Mellon U.) report: We observed location of EP250302a (Trigger ID: 01709132186; Zhu et al., GCN 39550) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at … [View More]

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[vsnet-grb-info 37564] EP250302a: Nanshan/HMT optical counterpart detection
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39550 SUBJECT: EP250302a: Nanshan/HMT optical counterpart detection DATE: 25/03/02 18:16:00 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> Z.P. Zhu, S.Q. Jiang, X. Liu, J. An, S.Y. Fu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of EP250302a detected by Einstein Probe (Trigger ID: 01709132186), using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. … [View More]

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[vsnet-grb-info 37563] IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39549 SUBJECT: IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/03/02 16:04:00 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2025-03-02 at 03:20:52.90 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_GOLD … [View More]

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[vsnet-grb-info 37562] GRB 250302A: Fermi GBM Final Real-time Localization
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39548 SUBJECT: GRB 250302A: Fermi GBM Final Real-time Localization DATE: 25/03/02 13:57:01 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 13:46:32 UT on 2 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250302A (trigger 762615997.991246 / 250302574). The on-ground calculated location, using the Fermi GBM trigger data, is RA = … [View More]

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[vsnet-grb-info 37561] GRB 250228A: Fermi GBM Final Localization
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39547 SUBJECT: GRB 250228A: Fermi GBM Final Localization DATE: 25/03/02 09:43:31 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> The Fermi GBM team reports the detection of a likely SHORT GRB "At 07:23:46.16 UT on 28 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250228A (trigger 762420231/250228308). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 94.90, Dec = … [View More]

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[vsnet-grb-info 37560] The EP-WXT trigger 01709132140 is likely a flaring star
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39546 SUBJECT: The EP-WXT trigger 01709132140 is likely a flaring star DATE: 25/03/02 04:53:52 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> X. Mao, S. X. Wen (NAOC, CAS), Y. Q. Zhao (USTC, PRIC), C. Y. Dai (NJU), W. Yuan (NAOC, CAS) report on behalf of the Einstein Probe team: The EP-WXT trigger (ID: 001709132140) on 2025-03-02 01:37:56(UTC) is likely a stellar flare associated with a High Proper Motion Star LP 378-313. Launched on January 9, … [View More]

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[vsnet-grb-info 37559] LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
by GCN Circulars 02 Mar '25

02 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39545 SUBJECT: LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations DATE: 25/03/02 03:55:41 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. Y. Li, J. W. Hu, Q. Y. Wu, M. J. Liu, R. D. Liang, H. Sun (NAOC, CAS), A. Li (BNU), C. Q. Shui (IHEP, CAS), M. H. Zhang, X. P. Xu, W. X. Wang, H. Q. Cheng, H. N. Yang, D. H. Zhao, X. Pan, Y. F. Xu, M. Zhang (NAOC, CAS), X. Y. Zhou (PRIC), Y. … [View More]C. Fu (BNU), S. F. Zhu (CSTU), Y. J. Zhang (THU), H. L. Peng (NJNU), G. Y. Zhao (SYU), C. Zhou (HUST), T. C. Zheng (PMO, CAS), Y. Chen, J. Guan, C. K. Li, S. M. Jia, H. S. Zhao, J. Zhang, M. Y. Ge, W. W. Cui, H. Feng, W. Li, C. Z. Liu, F. J. Lu, L. M. Song, J. Wang, J. J. Xu, D. W. Han, S. N. Zhang, X. F. Zhao (IHEP, CAS), Y. Liu, W. D. Zhang, Z. X. Ling, C. C. Jin, H. W. Pan, C. Zhang, W. Yuan (NAOC), B. Zhang (UNLV), L. Piro (INAF), V. Burwitz, P. Friedrich, N. Meidinger, K. Nandra, A. Rau (MPE), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), B. Cordier (CEA) report on behalf of the Einstein Probe team: We report on preliminary results of the observations targeting the sky regions of the LIGO/Virgo/KAGRA NS-BH gravitational-wave event S250206dm (The LIGO-Virgo-KAGRA Collaboration, GCN 39175) to search for any potentially associated X-ray source with the Einstein Probe (EP). Two rounds of observations were carried out with the Wide-field X-ray Telescope (WXT) and Follow-up X-ray Telescope (FXT) on board EP between Feb. 7th and 18th 2025. No promising X-ray transient candidates have been found. The information on the sky coverage and observations can be found at the web page https://ep.bao.ac.cn/ep/cms/article/view?id=185. First, two early WXT observations were performed, starting at 2025-02-07T02:55:12.000Z and 2025-02-07T03:40:22.000Z, about 4.5 hours and 6 hours after the GW event, respectively, each with an exposure time of 2400s. These observations covered 302 square degrees within (55% of) the 90% credible region of the updated LVK sky localization (The LIGO-Virgo-KAGRA Collaboration, GCN 39231). No new X-ray sources were detected. The 0.5-4 keV flux limits over the covered regions are set to be approximately 1.0 x 10^-11 erg/s/cm2 at the 90% confidence level in general. Then, 100 pointed FXT observations were carried out during Feb. 7th and 8th, each with a 300s-exposure, targeting galaxies located within the 90% credible region and the distance uncertainty range of S250206dm. The targets are among the top 500 galaxies that were selected from the GLADE+ catalog and prioritized based on their location, mass, and visibility to FXT. These observations covered 32 (24) square degree in the 90% (50%) credible region, setting 0.5-10 keV flux limits of generally 3e-13 erg/s/cm2 at the 90% confidence level. From Feb. 11th to 18th, 2025, the second round of observations consisted of tiling observations with FXT, covering 34 square degrees in (89% of) the 50% credible region of S250206dm. There were 59 observations performed, each with an exposure of 2000s, setting the average flux limits of approximately 5e-14 erg/s/cm2 at the 90% confidence level. We searched for transient or variable candidates in the FXT data which are apparently associated with the galaxies in the NED-LVS sample in the credible region and distance range of S250206dm (Cook et al. GCN 39235) within a radius of 30 arcsec. Two uncatalogued sources were found to exhibit significant flux decay from the FXT observations, whose details are listed in the table below. The fluxes are in the 0.5-10 keV band and estimated from spectral fitting with an absorbed powerlaw model. EPF J022731.1+551813 was not detected in the second observation, and an upper limit at the 90% confidence level is provided. We note that, however, a stellar flare origin of these two sources cannot be ruled out. ------------------------------------------------------------------------------------------------------ | Source Name | Obs_Time (UTC) | RA | DEC | Flux(erg/s/cm2) | Flux_err | ------------------------------------------------------------------------------------------------------ |EPF J022731.1+551813| 2025-02-13 08:35:07 | 36.8797 | 55.3037 | 5.28e-13 | 2.27e-14 | | | 2025-02-15 13:24:47 | | | <7.0e-14 | | ------------------------------------------------------------------------------------------------------ |EPF J022842.7+542051| 2025-02-08 07:59:43 | 37.1780 | 54.3475 | 6.61e-13 | 1.94e-14 | | | 2025-02-11 18:44:27 | 37.1839 | 54.3466 | 1.09e-13 | 4.27e-14 | | | 2025-02-15 10:12:36 | 37.1795 | 54.3469 | 1.07e-13 | 2.81e-14 | ------------------------------------------------------------------------------------------------------ Follow-up observations are encouraged to identify the nature of these two variable sources. 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/39545. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37558] GRB 250225B: VLT near-infrared afterglow confirmation
by GCN Circulars 01 Mar '25

01 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39544 SUBJECT: GRB 250225B: VLT near-infrared afterglow confirmation DATE: 25/03/01 18:56:01 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata <yyang(a)roma2.infn.it> Yu-Han Yang (U Rome), Muskan Yadav (U Rome), Eleonora Troja (U Rome) on behalf of the ERC BHianca team: We re-observed the field of GRB 250225B (Williams et al., GCN 39473) with the HAWKI imager on the ESO VLT UT4 (Yepun). Observations began at T+3.6 d days and were carried out … [View More]

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[vsnet-grb-info 37557] EP250228a: Optical observations with Kinder and Swift/UVOT
by GCN Circulars 01 Mar '25

01 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39543 SUBJECT: EP250228a: Optical observations with Kinder and Swift/UVOT DATE: 25/03/01 13:45:29 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> A. Aryan, Y. J. Yang (both NCU), A. K. H. Kong (NTHU), T.-W. Chen, H.-Y. Hsiao, C.-S. Lin (all NCU), J. Gillanders (Oxford), S. J. Smartt (Oxford/QUB), A. Sankar. K, Y.-C. Pan, C.-C. Ngeow, W.-J. Hou, M.-H. Lee, H.-C. Lin, C.-H. Lai, J.-K. Guo (… [View More]all NCU), S. Yang, L. L. Fan, Z. N. Wang, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP250228a (Liu et al., GCN 39525; Liu et al., GCN39531) using the 40cm SLT telescope at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al. 2024, arXiv:2406.09270). The first SLT epoch of observations in the i band started at 10:54 UT on the 28th of February 2025 (MJD = 60734.454), ~6.91 hrs after the EP trigger. We utilized the astroalign (Beroiz et al., 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al., 2022, ApJ, 935, 167) packages to align and stack the individual frames. In the stacked frame, we did not detect any uncataloged optical counterpart candidate within the EP-FXT localization error circle of radius 20 arcseconds. Moreover, we employed the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform template subtraction utilizing the "sfft" (Hu, 2022, ApJ, 936, 157) and "hotpants" (Becker A., 2015, ascl.soft. ascl:1504.004) algorithms using templates from SkyMapper DR4 (Onken et., 2024, PASA, 41, e061). We found no evidence of any prominent candidate optical counterpart in the difference images as well. We further employed AutoPhOT to perform the PSF photometry. The details of the observations and measured 3-sigma upper limits (in the AB system) were as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass SLT | i | 60734.454 | 6.91 | 300 * 12 | >20.2 | 1".20 | 2.44 SLT | r | 60734.503 | 8.08 | 300 * 24 | >19.9 | 1".43 | 2.53 The X-ray transient was also detected in Swift-XRT (Page et al., GCN39527). The Swift-XRT position coincided with a star (Gaia DR3 5563280076339409920; as updated by Liu et al., GCN39531), but we probably missed the flaring stage as we did not see any credible excess flux in the difference image. For this star, we measured an r-band magnitude of 15.33 +/- 0.03 mag and an i-band magnitude of 13.65 +/- 0.03 mag in our stacked frames. Our measured magnitudes for this source align perfectly with the archival values in the SkyMapper catalog. In addition, a preliminary U-band magnitude of 17.61 +/- 0.05 (stat) +/- 0.02 (sys) was measured from the quick-look Swift-UVOT observation. The presented measurements were calibrated using the field stars from the SkyMapper catalog and were not corrected for the expected Galactic foreground extinction corresponding to a reddening of A_i = 0.20 mag, and A_r = 0.27 mag in the direction of the transient (Schlafly & Finkbeiner 2011). View this GCN Circular online at https://gcn.nasa.gov/circulars/39543. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37556] Konus-Wind detection of GRB 250226A
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39542 SUBJECT: Konus-Wind detection of GRB 250226A DATE: 25/02/28 22:10:03 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 250226A (Fermi-GBM detection: The Fermi GBM team, GCN 39479; Pathak and Meegan, GCN 39530; EP-WXT detection: Jiang et al., GCN 39482; INTEGRAL SPI-ACS and … [View More]PICsIT detection: Thakur et al., GCN 39518) triggered Konus-Wind at T0=23700.486 s UT (06:35:00.486). The burst light curve shows a single emission episode which starts at ~T0-5 s and has a total duration of ~32 s. The emission is seen up to ~1 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250226_T23700/ As observed by Konus-Wind, the burst had a fluence of 1.17(-0.21,+0.28)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+0.438 s, of 3.45(-1.09,+1.18)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+24.832 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.16(-0.47,+0.68), the high energy photon index beta = -2.25(-0.38,+0.24), the peak energy Ep = 143(-28,+35) keV (chi2 = 64/97 dof). The spectrum near the maximum count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.60(-0.36,+0.54), the high energy photon index beta = -2.00(-8,+0.17), the peak energy Ep = 190(-53,+331) keV (chi2 = 86/97 dof). Assuming the redshift z=3.315 (Zhu et al. GCN 39487) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 2.80(-0.51,+0.67)x10^53 erg, the peak luminosity L_iso is 3.56(-1.12,+1.22)x10^53 erg/s, the rest-frame peak energy of the time-averaged spectrum Ep,i,z is 616(-119,+151) keV and the spectrum near the maximum count rate Ep,p,z is 822(-229,+1427) keV. With the obtained estimates, GRB 250226A is inside 68% prediction bands for both the 'Amati' and the 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB250226_T23700/GRB250226A_rest_frame.pdf All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/39542. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37555] GRB 250225B: EIRSAT-1 GMOD Detection
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39541 SUBJECT: GRB 250225B: EIRSAT-1 GMOD Detection DATE: 25/02/28 21:22:14 GMT FROM: Gabriel Finneran at School of Physics and Centre for Space Research, University College Dublin <gabriel.finneran(a)ucdconnect.ie> G. Finneran, C. McKenna, D. Murphy, C. de Barra, A. Ulyanov, P. McDermott, M. Doyle, R. Dunwoody, J. Mangan, G. Corcoran, L. Cotter, A. Empey, J. Fisher, F. Gibson Kiely, J. Thompson, D. McKeown, A. Martin-Carrillo, L. Hanlon, S. McBreen, … [View More]

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[vsnet-grb-info 37554] GRB 250226A: KAO Optical Upper Limit
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39540 SUBJECT: GRB 250226A: KAO Optical Upper Limit DATE: 25/02/28 20:48:07 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. M. Abdelaziz (NRIAG), M. Abdelkareem (NRIAG), E. Amin (NRIAG), A. Pozanenko (IKI) report on behalf of IKI GRB-FuN: We performed optical observations of the field of GRB 250226A (The Fermi GBM team, GCN 39479; V.Lipunov et. al, GCN 39481; Jiang et. al, GCN 39482; An et. al, GCN 39486; … [View More]

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[vsnet-grb-info 37553] GRB 250226A: AbAO AS-32 Optical Upper Limit
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39539 SUBJECT: GRB 250226A: AbAO AS-32 Optical Upper Limit DATE: 25/02/28 20:42:33 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 250226A (The Fermi GBM team, GCN 39479; V.Lipunov et. al, GCN 39481; Jiang et. al, GCN 39482; An et. al, GCN 39486; Zhu et. al, GCN 39487; Magnani … [View More]

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[vsnet-grb-info 37552] EP250227a: Global MASTER-Net observations report
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39538 SUBJECT: EP250227a: Global MASTER-Net observations report DATE: 25/02/28 17:54:50 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.… [View More]

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[vsnet-grb-info 37551] EP250223A: Upper limits from Fermi-GBM Observations
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39537 SUBJECT: EP250223A: Upper limits from Fermi-GBM Observations DATE: 25/02/28 17:47:57 GMT FROM: mariaedvige.ravasio(a)ru.nl M. E. Ravasio (Radboud Univ.), E. Burns (LSU), and P.G. Jonker (Radboud Univ.) report on behalf of the Fermi-GBM Team: Fermi-GBM had full spatial coverage of the transient EP250223A detected by EP-WXT (Lian et al., GCN 39429). There was no Fermi-GBM onboard trigger around the EP starting time T0=2025-02-23T15:02:05.66 UTC (Wang … [View More]

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[vsnet-grb-info 37550] EP250227a: TRT optical upper limit
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39536 SUBJECT: EP250227a: TRT optical upper limit DATE: 25/02/28 17:28:36 GMT FROM: sqjiang at NAOC <sqjiang(a)bao.ac.cn> S.Q. Jiang (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), J. An, X. Liu, S.Y. Fu, Z.P. Zhu, D. Xu, Z. Fan, W.X. Li, Y.N. Wang, N.C. Sun (NAOC) report on behalf of a large collaboration: We observed the field of EP250227a detected by EP (Wen et al., GCN 39532), using the 0.7-m telescope of the Thai Robotic Telescope … [View More]

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[vsnet-grb-info 37549] GRB 250225B: VLT/HAWKI near-infrared observations
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39535 SUBJECT: GRB 250225B: VLT/HAWKI near-infrared observations DATE: 25/02/28 17:08:01 GMT FROM: Nusrin Habeeb at University of Leicester <nh312(a)leicester.ac.uk> B.C. Rayson (U. Leicester), N. Habeeb (U. Leicester), N. R. Tanvir (U. Leicester), R. A. J. Eyles-Ferris (U. Leicester), R. Brivio (INAF-OAB), M. Ferro (INAF-OAB), A J. Levan (Radboud and Warwick), D. B. Malesani (DAWN/NBI and Radboud) report on behalf of the Stargate collaboration: We … [View More]

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[vsnet-grb-info 37548] EP250227a: Optical upper limits with Kinder observations
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39534 SUBJECT: EP250227a: Optical upper limits with Kinder observations DATE: 25/02/28 16:56:52 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> A. Aryan (NCU), A. K. H. Kong (NTHU), T.-W. Chen, H.-Y. Hsiao, C.-S. Lin (all NCU), J. Gillanders (Oxford), S. J. Smartt (Oxford/QUB), Y. J. Yang, A. Sankar. K, Y.-C. Pan, C.-C. Ngeow, W.-J. Hou, M.-H. Lee, H.-C. Lin, C.-H. Lai, J.-K. Guo (all NCU),… [View More] S. Yang, L. L. Fan, Z. N. Wang, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP250227a (Wen et al., GCN 39532) using the 40cm SLT telescope at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al. 2024, arXiv:2406.09270). The first SLT epoch of observations in the i band started at 15:53 UT on the 27th of February 2025 (MJD = 60733.662), ~11.22 hrs after the EP trigger, while the first SLT epoch of observations in the r band started at 16:28 UT on the 27th of February 2025 (MJD = 60733.686), ~11.79 hrs after the EP trigger. We utilized the astroalign (Beroiz et al., 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al., 2022, ApJ, 935, 167) packages to align and stack the individual frames. We did not detect any uncataloged optical counterpart candidate within the EP-WXT localization error circle of radius 2.7 arcminutes. We further employed the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform PSF photometry on our stacked frames. The details of the observations and measured three sigma upper limits (in the AB system) were as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass SLT | i | 60733.662 | 11.22 | 300 * 6 | >21.1 | 1".47 | 1.80 SLT | r | 60733.686 | 11.79 | 300 * 12 | >21.5 | 1".46 | 1.49 The non-detection of any prominent optical counterpart is consistent with Malesani et al., (GCN 39533). The presented upper limits were calibrated using the field stars from the Pan-STARRS1 catalog and were not corrected for the expected Galactic foreground extinction corresponding to a reddening of A_i = 0.12 mag and A_r = 0.16 mag, respectively, in the direction of the transient (Schlafly & Finkbeiner 2011). View this GCN Circular online at https://gcn.nasa.gov/circulars/39534. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37547] EP250227a: NOT optical observations
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39533 SUBJECT: EP250227a: NOT optical observations DATE: 25/02/28 16:36:03 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo(a)ucd.ie> D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Martin-Carrillo (UCD), A. J. Levan (Radboud Univ and Warwick Univ.), F. E. Bauer (PUC), P. G. Jonker (Radboud Univ), M. Alejandra Diaz Teodori (NOT and Turku Univ.), Roar H. Rasmussen (NOT and Aarhus Univ.), Saskia Schlagenhauf (QUB), … [View More]

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[vsnet-grb-info 37546] EP250227a: Einstein Probe detected of a fast X-ray transient
by GCN Circulars 28 Feb '25

28 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39532 SUBJECT: EP250227a: Einstein Probe detected of a fast X-ray transient DATE: 25/02/28 15:52:07 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> W.F. Wen (SZTU), J. H. Wu (GZHU), H. Z. Wu (HUST), B. -T. Wang (YNAO, CAS), Z. X. Ling(NAO, CAS) report on behalf of the Einstein Probe team: We report on the detection of a fast X-ray transient EP250227a (trigger ID: 11916647689) at 2025-02-27 04:39:40 (UTC) by the Wide-field X-ray Telescope (WXT) on … [View More]

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