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

[vsnet-grb-info 37496] EP250226a: Global MASTER-Net observations report
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39484 SUBJECT: EP250226a: Global MASTER-Net observations report DATE: 25/02/26 08:09:29 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.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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP250226a ( EP Team et al., GCN 39482) errorbox 460 sec after notice time and 3834 sec after trigger time at 2025-02-26 07:39:10 UT, with upper limit up to 20.4 mag. The observations began at zenith distance = 56 deg. The sun altitude is -32.9 deg. The galactic latitude b = 60 deg., longitude l = 28 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2792303 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3865 | 2025-02-26 07:39:10 | MASTER-OAFA | (14h 57m 01.08s , +20d 57m 34.1s) | C | 60 | 20.4 | 4736 | 2025-02-26 07:53:41 | MASTER-OAFA | (14h 57m 24.39s , +21d 12m 59.9s) | C | 60 | 20.4 | 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/39484. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37495] Swift GRB 250225B: Global MASTER-Net observations report
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39483 SUBJECT: Swift GRB 250225B: Global MASTER-Net observations report DATE: 25/02/26 07:32:53 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.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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 250225B ( M. A. Williams et al., GCN 39473) errorbox 41481 sec after notice time and 41703 sec after trigger time at 2025-02-26 07:14:16 UT, with upper limit up to 16.6 mag. The observations began at zenith distance = 83 deg. The sun altitude is -37.0 deg. The galactic latitude b = -35 deg., longitude l = 360 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2791924 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 41793 | MASTER-OAFA | C | 180 | 16.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39483. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37494] EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39482 SUBJECT: EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient DATE: 25/02/26 07:30:36 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> S. Q. Jiang (NAO, CAS), B.-T. Wang (YNAO, CAS), H. Z. Wu (HUST), T. Zhao, Y.J. Song, Y. Liu (NAO, CAS) report on behalf of the Einstein Probe team: We report on the detection of an X-ray transient EP250226a at 2025-02-26 06:35:16 (UTC) by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The WXT position of the source is R.A. = 224.273 deg, DEC = 20.973 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The trigger time and the position are generally consistent with the likely long GRB 250226A detected by Fermi (GCN 39479). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error cirlce, an uncatalogued X-ray source was detected at R.A. = 224.2668 deg, DEC = 20.9743 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). 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/39482. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37493] Fermi GRB 250226A: Global MASTER-Net observations report
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39481 SUBJECT: Fermi GRB 250226A: Global MASTER-Net observations report DATE: 25/02/26 07:19:05 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.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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 250226A ( Fermi GBM team, GCN 39479) errorbox 24 sec after notice time and 42 sec after trigger time at 2025-02-26 06:35:39 UT, with upper limit up to 20.6 mag. The observations began at zenith distance = 68 deg. The sun altitude is -42.6 deg. The galactic latitude b = 63 deg., longitude l = 32 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2792277 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 47 | 2025-02-26 06:35:39 | MASTER-OAFA | (14h 37m 17.00s , +28d 44m 10.7s) | C | 10 | 17.3 | 62 | 2025-02-26 06:35:39 | MASTER-OAFA | (14h 37m 17.01s , +28d 44m 10.7s) | C | 40 | 18.0 | Coadd 48 | 2025-02-26 06:35:40 | MASTER-OAFA | (14h 47m 34.56s , +29d 06m 42.6s) | C | 10 | 18.8 | 73 | 2025-02-26 06:35:40 | MASTER-OAFA | (14h 47m 34.57s , +29d 06m 42.7s) | C | 60 | 19.9 | Coadd 133 | 2025-02-26 06:35:40 | MASTER-OAFA | (14h 47m 34.56s , +29d 06m 42.7s) | C | 180 | 20.5 | Coadd 97 | 2025-02-26 06:36:24 | MASTER-OAFA | (14h 37m 16.85s , +28d 44m 13.0s) | C | 20 | 17.7 | 98 | 2025-02-26 06:36:25 | MASTER-OAFA | (14h 47m 34.39s , +29d 06m 43.3s) | C | 20 | 19.2 | 132 | 2025-02-26 06:37:04 | MASTER-OAFA | (14h 37m 16.73s , +28d 44m 14.3s) | C | 10 | 17.3 | 143 | 2025-02-26 06:37:04 | MASTER-OAFA | (14h 47m 34.22s , +29d 06m 43.3s) | C | 30 | 19.5 | 168 | 2025-02-26 06:37:40 | MASTER-OAFA | (14h 37m 16.62s , +28d 44m 15.1s) | C | 10 | 17.2 | 193 | 2025-02-26 06:37:40 | MASTER-OAFA | (14h 37m 16.64s , +28d 44m 15.1s) | C | 60 | 18.5 | Coadd 178 | 2025-02-26 06:37:40 | MASTER-OAFA | (14h 47m 34.11s , +29d 06m 43.3s) | C | 30 | 19.6 | 223 | 2025-02-26 06:37:40 | MASTER-OAFA | (14h 47m 34.28s , +29d 06m 43.1s) | C | 120 | 20.0 | Coadd 209 | 2025-02-26 06:38:16 | MASTER-OAFA | (14h 37m 16.46s , +28d 44m 15.8s) | C | 20 | 17.8 | 219 | 2025-02-26 06:38:16 | MASTER-OAFA | (14h 47m 33.97s , +29d 06m 42.9s) | C | 40 | 19.7 | 260 | 2025-02-26 06:39:02 | MASTER-OAFA | (14h 37m 16.25s , +28d 44m 16.5s) | C | 30 | 18.0 | 270 | 2025-02-26 06:39:02 | MASTER-OAFA | (14h 47m 33.77s , +29d 06m 42.4s) | C | 50 | 19.9 | 321 | 2025-02-26 06:39:58 | MASTER-OAFA | (14h 37m 15.96s , +28d 44m 16.6s) | C | 40 | 18.3 | 331 | 2025-02-26 06:39:58 | MASTER-OAFA | (14h 47m 33.52s , +29d 06m 41.8s) | C | 60 | 19.9 | 439 | 2025-02-26 06:41:46 | MASTER-OAFA | (14h 38m 47.22s , +23d 27m 51.0s) | C | 60 | 18.4 | 529 | 2025-02-26 06:41:46 | MASTER-OAFA | (14h 38m 47.22s , +23d 27m 51.0s) | C | 240 | 19.5 | Coadd 449 | 2025-02-26 06:41:46 | MASTER-OAFA | (14h 48m 37.68s , +23d 50m 29.6s) | C | 80 | 20.2 | 559 | 2025-02-26 06:41:46 | MASTER-OAFA | (14h 48m 37.68s , +23d 50m 29.7s) | C | 300 | 20.6 | Coadd 535 | 2025-02-26 06:43:12 | MASTER-OAFA | (14h 38m 46.84s , +23d 27m 50.2s) | C | 80 | 18.6 | 545 | 2025-02-26 06:43:12 | MASTER-OAFA | (14h 48m 37.34s , +23d 50m 28.1s) | C | 100 | 20.2 | 652 | 2025-02-26 06:44:59 | MASTER-OAFA | (14h 38m 46.33s , +23d 27m 48.1s) | C | 100 | 18.8 | 662 | 2025-02-26 06:44:59 | MASTER-OAFA | (14h 48m 36.92s , +23d 50m 26.1s) | C | 120 | 20.2 | 793 | 2025-02-26 06:47:04 | MASTER-OAFA | (14h 38m 45.75s , +23d 27m 45.8s) | C | 130 | 18.7 | 953 | 2025-02-26 06:47:04 | MASTER-OAFA | (14h 38m 45.75s , +23d 27m 45.8s) | C | 450 | 19.7 | Coadd 803 | 2025-02-26 06:47:05 | MASTER-OAFA | (14h 48m 36.39s , +23d 50m 23.4s) | C | 150 | 20.2 | 973 | 2025-02-26 06:49:50 | MASTER-OAFA | (14h 38m 45.03s , +23d 27m 41.9s) | C | 160 | 18.8 | 983 | 2025-02-26 06:49:50 | MASTER-OAFA | (14h 49m 41.16s , +23d 48m 31.7s) | C | 180 | 20.2 | 1163 | 2025-02-26 06:49:50 | MASTER-OAFA | (14h 49m 41.16s , +23d 48m 31.8s) | C | 540 | 20.6 | Coadd 1167 | 2025-02-26 06:53:04 | MASTER-OAFA | (14h 38m 44.30s , +23d 27m 37.0s) | C | 160 | 18.7 | 1177 | 2025-02-26 06:53:04 | MASTER-OAFA | (14h 49m 40.51s , +23d 48m 27.3s) | C | 180 | 20.1 | 1362 | 2025-02-26 06:56:19 | MASTER-OAFA | (14h 38m 43.40s , +23d 27m 31.4s) | C | 160 | 18.6 | 1372 | 2025-02-26 06:56:19 | MASTER-OAFA | (14h 49m 39.69s , +23d 48m 22.0s) | C | 180 | 20.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39481. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37492] Fermi trigger No 762205158: Global MASTER-Net observations report
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39480 SUBJECT: Fermi trigger No 762205158: Global MASTER-Net observations report DATE: 25/02/26 07:18:11 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.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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB250225.82 (trigger No 762205158,20h 13m 48.00s , -40d 49m 58.8s, R=4.37) errorbox 40804 sec after notice time and 40845 sec after trigger time at 2025-02-26 06:59:59 UT, with upper limit up to 17.7 mag. The observations began at zenith distance = 83 deg. The sun altitude is -39.2 deg. The galactic latitude b = -33 deg., longitude l = 0 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2791902 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 40925 | 2025-02-26 06:59:59 | MASTER-OAFA | (20h 11m 46.26s , -42d 14m 07.7s) | C | 160 | 17.6 | 41131 | 2025-02-26 07:03:24 | MASTER-OAFA | (20h 11m 46.06s , -42d 12m 55.8s) | C | 160 | 17.7 | 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/39480. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37491] GRB 250226A: Fermi GBM Final Real-time Localization
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39479 SUBJECT: GRB 250226A: Fermi GBM Final Real-time Localization DATE: 25/02/26 06:42:51 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 06:34:57 UT on 26 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250226A (trigger 762244502.334384 / 250226274). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 222.1, Dec = 23.8 (J2000 degrees, equivalent to J2000 14h 48m, 23d 48'), with a statistical uncertainty of 3.9 degrees. The angle from the Fermi LAT boresight is 111.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250226274/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250226274/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250226274/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39479. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37490] EP250225a: Global MASTER-Net observations report
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39478 SUBJECT: EP250225a: Global MASTER-Net observations report DATE: 25/02/26 05:31:23 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, 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP250225a ( EP Team et al., GCN 39475) errorbox 364 sec after notice time and 58846 sec after trigger time at 2025-02-26 04:34:36 UT, with upper limit up to 20.5 mag. The observations began at zenith distance = 30 deg. The sun altitude is -50.1 deg. The galactic latitude b = 31 deg., longitude l = 238 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2792193 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 58876 | 2025-02-26 04:34:36 | MASTER-OAFA | (09h 24m 15.36s , -04d 59m 40.0s) | C | 60 | 20.5 | 60307 | 2025-02-26 04:58:27 | MASTER-OAFA | (09h 24m 17.17s , -05d 00m 37.2s) | C | 60 | 20.4 | 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/39478. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37489] EP250225a: GSP optical upper limit
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39477 SUBJECT: EP250225a: GSP optical upper limit DATE: 25/02/26 05:25:33 GMT FROM: Wenxiong Li <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 EP250225a by the Einstein Probe (Jiang et al., GCN 39475) with the Sinistro instrument mounted on the 1-m telescope of the LCO, we initiated observations of the fast X-ray transient location starting on 2025 Feb 26th at 04:50:50 UT (~15 hours after the EP/WXT trigger) in the r band. These observations were conducted using the 1-meter telescope at the Las Cumbres Observatory node located at the Cerro Tololo Inter-American Observatory in Chile. No new optical source was detected in the co-added images within the EP/WXT error box down to ~21.5 mag. These observations were taken as part of the Global Supernova Project. View this GCN Circular online at https://gcn.nasa.gov/circulars/39477. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37488] EP250223a: GMG Optical Observation
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39476 SUBJECT: EP250223a: GMG Optical Observation DATE: 25/02/26 04:26:24 GMT FROM: Boting Wang at Yunnan Observatories, CAS <wangbaiting(a)ynao.ac.cn> B.-T. Wang, R.-Z. Li, F.-F. Song, J. Mao, D.-Q. Wang, and J.-M. Bai (YNAO, CAS) report: We observed the field of EP250223a (Lian et al., GCN 39429, T0 at 2025-02-23T15:04:35.749) using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2025-02-25T12:45:36.92, about 45.68 hours after the trigger. The optical counterpart of EP250223a (Hauptmann et al., GCN 39436; Wu et al., GCN 39439; Pérez-Fournon et al., GCN 39440; Izzo et al., GCN 39441; Xin et al., GCN 39445; Guo et al., GCN 39447; An et al., GCN 39449; Ducoin et al., GCN 39453; O’Neill et al., GCN 39455; Aryan et al., GCN 39464; Saikia et al., GCN 39472), with a redshift of 2.756 (Levan et al., GCN 39438), was detected within the error box of EP/FXT (Lian et al., GCN 39429). The preliminary analysis results are shown as follows: | tmid-t0 (hours) | Filter | Exposure (s) | Magnitude (AB) | 5-sigma U.L. | | ----------- |------- | ------------------ | -------------- | ------ | | 45.85 | sdssr | 1200 | 20.82 +/- 0.08 | 21.9 | The given magnitudes are derived based on calibration against Pan-STARRS1 field stars and are not corrected for the expected Galactic foreground extinction. We warmly thank the staff at the Lijiang Observatory for their efforts in conducting the observation. View this GCN Circular online at https://gcn.nasa.gov/circulars/39476. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37487] EP250225a: Einstein Probe detected of a fast X-ray transient
by GCN Circulars 26 Feb '25

26 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39475 SUBJECT: EP250225a: Einstein Probe detected of a fast X-ray transient DATE: 25/02/26 04:23:32 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> S.Q. Jiang (NAO, CAS), B.-T. Wang (YNAO, CAS), H.Z. Wu (HUST), T. Zhao, Y.J. Song, Y. Liu (NAO, CAS) report on behalf of the Einstein Probe team: We report on the detection of a fast X-ray transient EP250225a at 2025-02-25T12:13:50 (UTC) by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The position of the source is R.A. = 141.272 deg, DEC = -4.932 deg (J2000) with an uncertainty of 2.8 arcmin (radius, 90% C.L. statistical and systematic). The transient event lasted for about 600 seconds. The average 0.5-4 keV spectrum can be fitted with an absorbed powerlaw model, with nH fixed at the Galactic value of 3.0 x 10^20 cm^-2 and a photon index of 2.5 (-0.9/+1.1). The unabsorbed average 0.5-4 keV flux is estimated to be 4.3 (-1.3/+2.1) x 10^-11 erg/s/cm2. The uncertainties are at the 90% confidence level for the above parameters. Further FXT observations are scheduled. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/39475. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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