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

[vsnet-grb-info 38126] IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 07 Apr '25

07 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40103 SUBJECT: IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/04/07 08:06:32 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2025-04-06 at 22:50:35.34 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 alert stream. The average astrophysical neutrino purity for bronze alerts is 50%. This alert has an estimated false alarm rate of 0.9358 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/140752_31006975.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2025-04-06 Time: 22:50:35.34 UT RA: 81.47 (+0.54, -0.53 deg 90% PSF containment) J2000 Dec: 16.96 (+0.42, -0.50 deg 90% PSF containment) J2000 No gamma-ray sources from 4FGL or 3FHL catalogs are in the 90% uncertainty region. We encourage further follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. 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 View this GCN Circular online at https://gcn.nasa.gov/circulars/40103. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38125] IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
by GCN Circulars 07 Apr '25

07 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40102 SUBJECT: IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit DATE: 25/04/07 06:43:32 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Ny Avo Rakotondrainibe (LAM), Noémie Globus (UNAM), Jean-Grégoire Ducoin (CPPM), Kin Ocelotl López (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We observed the field of the IceCube 250406.951 (goldtrack) event with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico on the night of 2025-04-07 UTC. COLIBRÍ tiled the IceCube error region from 03:09 UTC to 04:18 UTC (from T+4.3 h to T+5.5 h after the trigger) with a total exposure of 47 minutes. The data were coadded with the COLIBRÍ pipeline and analysed in STDWeb/STDPipe (Karpov 2025). Comparing our observations (and after performing image subtraction) against Pan-STARRS DR2, we detect no evident uncatalogued sources within the observed field to a 5-sigma limiting AB magnitude of: i > 22.2 This non-detection is consistent with the reported by Becerra et al., GCN 40101. This value is not corrected for the Galactic extinction. We warmly thank the COLIBRÍ and DDRAGO engineering teams and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/40102. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38124] IceCube 250406.951: DDOTI Optical Observations
by GCN Circulars 07 Apr '25

07 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40101 SUBJECT: IceCube 250406.951: DDOTI Optical Observations DATE: 25/04/07 06:03:17 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Sahil Atri (U Roma), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observed the field of the IceCube 250406.951 (goldtrack) event with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on the Sierra of San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2025-04-07 UTC. DDOTI observed the IceCube error region from 03:12 UTC to 03:40 UTC (from T+4.4 h to T+4.8 h after the trigger) with a total exposure of 24 minutes. Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogues and after performed image subtraction against PanSTARRS PS1 DR2, we detect no evident uncatalogued sources within the observed field to a 5-sigma limiting AB magnitude of w > 19.7 This value is not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/40101. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38123] GRB 250406A: AstroSat CZTI detection
by GCN Circulars 07 Apr '25

07 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40100 SUBJECT: GRB 250406A: AstroSat CZTI detection DATE: 25/04/07 04:27:16 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, 42, 73) showed the detection of a long duration GRB 250406A which was also detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 40094). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-04-06 14:38:19.0 UTC. The measured peak count rate associated with the burst is 126 (+25, -17) counts/s above the background in the combined data of three quadrants (out of four), with a total of 1195 (+285, -117) counts. The local mean background count rate was 226 (+1, -6) counts/s. Using cumulative rates, we measure a T90 of 17 (+4, -2) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-04-06 14:38:17.9 UTC. The measured peak count rate associated with the burst is 329 (+70, -44) counts/s above the background in the combined data of all quadrants, with a total of 2697 (+493, -543) counts. The local mean background count rate was 1320 (+7, -8) counts/s. We measure a T90 of 16 (+5, -5) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/40100. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38122] IceCube Alert 250406.95: Global MASTER-Net observations report
by GCN Circulars 06 Apr '25

06 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40099 SUBJECT: IceCube Alert 250406.95: Global MASTER-Net observations report DATE: 25/04/06 23:39:44 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 IceCube Alert 250406.95 (trigger No 31006975,05h 27m 14.40s , +16d 40m 08.4s, R=0.51) errorbox 1665 sec after notice time and 1717 sec after trigger time at 2025-04-06 23:19:12 UT, with upper limit up to 19.3 mag. Observations started at twilight. The observations began at zenith distance = 57 deg. The sun altitude is -12.5 deg. The galactic latitude b = -9 deg., longitude l = 189 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2835304 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1798 | 2025-04-06 23:19:12 | MASTER-OAFA | (05h 36m 30.18s , +17d 17m 13.8s) | C | 160 | 15.5 | 1984 | 2025-04-06 23:22:18 | MASTER-OAFA | (05h 36m 29.96s , +17d 17m 16.2s) | C | 160 | 16.3 | 2144 | 2025-04-06 23:22:18 | MASTER-OAFA | (05h 36m 29.96s , +17d 17m 16.2s) | C | 480 | 16.9 | Coadd 2170 | 2025-04-06 23:25:24 | MASTER-OAFA | (05h 36m 29.72s , +17d 17m 19.0s) | C | 160 | 16.5 | 2180 | 2025-04-06 23:25:25 | MASTER-OAFA | (05h 27m 00.20s , +16d 54m 03.9s) | C | 180 | 15.6 | 2356 | 2025-04-06 23:28:31 | MASTER-OAFA | (05h 36m 29.47s , +17d 17m 21.0s) | C | 160 | 16.8 | 2366 | 2025-04-06 23:28:31 | MASTER-OAFA | (05h 27m 00.08s , +16d 54m 05.7s) | C | 180 | 19.1 | 2542 | 2025-04-06 23:31:37 | MASTER-OAFA | (05h 36m 29.25s , +17d 17m 22.1s) | C | 160 | 16.6 | 2552 | 2025-04-06 23:31:37 | MASTER-OAFA | (05h 26m 59.99s , +16d 54m 07.1s) | C | 180 | 19.3 | 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/40099. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38121] Fermi trigger No 765663719: Global MASTER-Net observations report
by GCN Circulars 06 Apr '25

06 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40098 SUBJECT: Fermi trigger No 765663719: Global MASTER-Net observations report DATE: 25/04/06 20:46:19 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-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 GRB250406.85 (trigger No 765663719,19h 59m 09.60s , +36d 07m 12.0s, R=7.99) errorbox 216 sec after notice time and 235 sec after trigger time at 2025-04-06 20:25:49 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 40 deg. The sun altitude is -18.6 deg. The galactic latitude b = 3 deg., longitude l = 73 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2835171 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 265 | 2025-04-06 20:25:49 | MASTER-Tunka | (19h 43m 55.63s , +35d 11m 35.6s) | C | 60 | 17.5 | 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/40098. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38120] EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
by GCN Circulars 06 Apr '25

06 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40097 SUBJECT: EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14 DATE: 25/04/06 19:33:24 GMT FROM: qiang xi <xiqiang051(a)gmail.com> Qiang-Xi (UCAS), Yiming-Mao (NAOC), Xinxiang-Sun (NAOC), Ningchen-Sun (NAOC), Junjie-Jin (NAOC), Min-He (NAOC) report: We detected an optical counterpart for the field of EP 250404A using two independent facilities: the 70 cm telescope UCAS-70 and the 35 cm telescope XL-C14. The optical counterpart was observed at the coordinates: **RA = 08h20m14.54s, Dec = +35°31′42.2″.** Stacked imaging of the field has revealed a clear optical transient. The photometric measurements derived from the stacked images are summarized below. In our analysis, the photometry in the Johnson band was calibrated from APASS data converted using the Lupton (2005) equations, while the SDSS band data were calibrated against the SDSS star catalog. The observation time reported corresponds to the median of the individual exposure times. | Median Time (UT) | Telescope | Exposure (s) | Filter | Magnitude | Err | | ----------------------- | --------- | ------------ | ------ | ---------------- | ---- | | 2025-04-04 15:42:35.500 | UCAS-70 | 6×180 | B | 18.73 | 0.24 | | 2025-04-04 15:45:44.199 | UCAS-70 | 6×180 | V | 17.89 | 0.12 | | 2025-04-04 15:48:52.780 | UCAS-70 | 6×180 | R | 17.18 | 0.14 | | 2025-04-04 15:52:01.952 | UCAS-70 | 6×180 | I | 16.76 | 0.13 | | 2025-04-04 16:04:43.721 | XL-C14 | 11×120 | g | <22.10( 3-sigma limit) | | | 2025-04-04 16:17:19.682 | XL-C14 | 13×120 | r | 17.59 | 0.19 | | 2025-04-04 16:15:12.716 | XL-C14 | 13×120 | i | 17.15 | 0.20 | | 2025-04-04 15:58:22.729 | XL-C14 | 8×120 | z | <17.41( 3-sigma limit) | | This measurement has not been corrected for galaxy extinction. Our observations are consistent with other already reported Jiang et al. (GCN 40052), Perez-Garcia et al. (GCN 40053), Du et al. (GCN 40058), Zhu et al. (GCN 40061), Konno et al. (GCN 40063), Odeh et al. (GCN 40064), Lipunov et al. (GCN 40066), Min-He et al. (GCN 40069), Lipunov et al. (GCN 40070), Perez-Fournon et al. (GCN 40071), Jelinek et al. (GCN 40072), Rakotondrainibe et al. (GCN 40073), Taguchi et al. (GCN 40074), Brivio et al. (GCN 40075), Ruocco (GCN 40076), Martin-Carrillo et al. (GCN 40080), Pavoni et al. (GCN 40083), Li et al. (GCN 40084), Yin et al. (GCN 40085), Pankov et al. (GCN 40086), Chen et al. (GCN 40088), Chen et al. (GCN 40089), Pankov et al. (GCN 40090), Leonini et al. (GCN 40093), Leonini et al(GCN40095). View this GCN Circular online at https://gcn.nasa.gov/circulars/40097. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38119] Fermi GRB 250406A: Global MASTER-Net observations report
by GCN Circulars 06 Apr '25

06 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40096 SUBJECT: Fermi GRB 250406A: Global MASTER-Net observations report DATE: 25/04/06 18:15:59 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-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 250406A ( Fermi GBM team, GCN 40094) errorbox 9143 sec after notice time and 9171 sec after trigger time at 2025-04-06 17:11:03 UT, with upper limit up to 18.1 mag. Observations started at twilight. The observations began at zenith distance = 68 deg. The sun altitude is -9.9 deg. The galactic latitude b = -54 deg., longitude l = 308 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2834949 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9202 | 2025-04-06 17:11:03 | MASTER-SAAO | (00h 25m 46.55s , -63d 33m 50.2s) | C | 60 | 16.6 | 9281 | 2025-04-06 17:12:22 | MASTER-SAAO | (00h 43m 35.96s , -63d 32m 39.4s) | C | 60 | 16.8 | 9360 | 2025-04-06 17:13:41 | MASTER-SAAO | (00h 24m 01.48s , -61d 38m 12.8s) | C | 60 | 16.8 | 9439 | 2025-04-06 17:15:01 | MASTER-SAAO | (00h 40m 43.37s , -61d 39m 07.2s) | C | 60 | 17.0 | 9519 | 2025-04-06 17:16:20 | MASTER-SAAO | (00h 27m 48.66s , -65d 26m 57.7s) | C | 60 | 17.2 | 9803 | 2025-04-06 17:21:04 | MASTER-SAAO | (00h 09m 41.55s , -63d 33m 51.5s) | C | 60 | 17.6 | 9889 | 2025-04-06 17:22:30 | MASTER-SAAO | (00h 25m 49.55s , -63d 32m 19.4s) | C | 60 | 17.7 | 10129 | 2025-04-06 17:26:30 | MASTER-SAAO | (00h 43m 41.72s , -63d 33m 01.9s) | C | 60 | 17.9 | 10209 | 2025-04-06 17:27:50 | MASTER-SAAO | (00h 23m 59.75s , -61d 39m 57.8s) | C | 60 | 17.7 | 10289 | 2025-04-06 17:29:10 | MASTER-SAAO | (00h 40m 51.41s , -61d 39m 35.0s) | C | 60 | 17.9 | 10368 | 2025-04-06 17:30:29 | MASTER-SAAO | (00h 27m 50.49s , -65d 25m 58.4s) | C | 60 | 17.8 | 10653 | 2025-04-06 17:35:14 | MASTER-SAAO | (00h 09m 43.11s , -63d 32m 50.4s) | C | 60 | 18.0 | 10733 | 2025-04-06 17:36:34 | MASTER-SAAO | (00h 25m 48.42s , -63d 31m 49.8s) | C | 60 | 17.9 | 10812 | 2025-04-06 17:37:53 | MASTER-SAAO | (00h 43m 45.24s , -63d 32m 51.2s) | C | 60 | 18.1 | 10892 | 2025-04-06 17:39:13 | MASTER-SAAO | (00h 24m 03.87s , -61d 39m 50.1s) | C | 60 | 17.9 | 10971 | 2025-04-06 17:40:32 | MASTER-SAAO | (00h 40m 54.53s , -61d 39m 38.8s) | C | 60 | 17.8 | 11051 | 2025-04-06 17:41:52 | MASTER-SAAO | (00h 27m 55.06s , -65d 25m 49.8s) | C | 60 | 17.8 | 11335 | 2025-04-06 17:46:36 | MASTER-SAAO | (00h 09m 48.00s , -63d 32m 47.3s) | C | 60 | 17.8 | 11415 | 2025-04-06 17:47:56 | MASTER-SAAO | (00h 25m 51.70s , -63d 31m 45.0s) | C | 60 | 17.9 | 11494 | 2025-04-06 17:49:15 | MASTER-SAAO | (00h 43m 49.94s , -63d 32m 44.3s) | C | 60 | 17.9 | 11574 | 2025-04-06 17:50:35 | MASTER-SAAO | (00h 24m 06.65s , -61d 39m 45.5s) | C | 60 | 17.9 | 11653 | 2025-04-06 17:51:54 | MASTER-SAAO | (00h 40m 58.05s , -61d 39m 30.5s) | C | 60 | 17.9 | 12144 | 2025-04-06 18:00:05 | MASTER-SAAO | (00h 28m 06.48s , -65d 25m 50.6s) | C | 60 | 17.9 | 12430 | 2025-04-06 18:04:52 | MASTER-SAAO | (00h 10m 03.09s , -63d 32m 45.1s) | C | 60 | 17.8 | 12510 | 2025-04-06 18:06:11 | MASTER-SAAO | (00h 25m 59.78s , -63d 33m 39.9s) | C | 60 | 17.8 | 12589 | 2025-04-06 18:07:30 | MASTER-SAAO | (00h 43m 57.06s , -63d 33m 07.7s) | C | 60 | 17.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40096. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38118] GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
by GCN Circulars 06 Apr '25

06 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40095 SUBJECT: GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations. DATE: 25/04/06 17:44:24 GMT FROM: Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, Messina, Italy <giovannicalapai(a)tiscali.it> Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, (Messina) Italy Member of: GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. Report: We observed the field of GRB 250404A detected by Fermi Gamma-ray Burst Monitor (GBM team, GCN 40050) with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3. The observations were started at 2025-04-04 22:45 UT (approximately 8.42 hours after burst) stacking a set of unfiltered CCD image. The observations were made with modest visibility conditions: passing clouds and Moon (illumin. 48%, dist. 19°) The OT was detected at the following position (+/- 0.3 arcsec): RA (J2000.0) 08h 20m 14.59s Decl. (J2000.0) +35° 31' 41.5" Photometry was obtained using nearby PanSTARRS stars as follows: Observation Mid-Time T-T0 (hr) Exposure Filter Mag. Err. 2025-04-04 23:27:00 UT 9.12 82x60s CR 20.16 +/-0.2 Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied. Our observations are consistent with other already reported Jiang et al. (GCN 40052), Perez-Garcia et al. (GCN 40053), Du et al. (GCN 40058), Zhu et al. (GCN 40061), Konno et al. (GCN 40063), Odeh et al. (GCN 40064), Lipunov et al. (GCN 40066), Min-He et al. (GCN 40069), Lipunov et al. (GCN 40070), Perez-Fournon et al. (GCN 40071), Jelinek et al. (GCN 40072), Rakotondrainibe et al. (GCN 40073), Taguchi et al. (GCN 40074), Brivio et al. (GCN 40075), Ruocco (GCN 40076), Martin-Carrillo et al. (GCN 40080), Pavoni et al. (GCN 40083), Li et al. (GCN 40084), Yin et al. (GCN 40085), Pankov et al. (GCN 40086), Chen et al. (GCN 40088), Chen et al. (GCN 40089), Pankov et al. (GCN 40090), Leonini et al. (GCN 40093). The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40095. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38117] GRB 250406A: Fermi GBM Final Real-time Localization
by GCN Circulars 06 Apr '25

06 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40094 SUBJECT: GRB 250406A: Fermi GBM Final Real-time Localization DATE: 25/04/06 14:48:42 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 14:38:11 UT on 6 Apr 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250406A (trigger 765643096.56557 / 250406610). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 6.2, Dec = -63.2 (J2000 degrees, equivalent to J2000 00h 24m, -63d 12'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 29.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250406610/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250406610/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250406610/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40094. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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