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

[vsnet-grb-info 37394] GRB 250219A: NOT optical observations
by GCN Circulars 20 Feb '25

20 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39383 SUBJECT: GRB 250219A: NOT optical observations DATE: 25/02/20 08:48:49 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> S. Y. Fu (NAOC), J. T. Palmerio (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud Univ.), L. Cotter (UCD), D. Xu (NAOC), B. Schneider (LAM), B. N. Hauptmann (NOT and DTU Space), A. M. Kadela (NOT and NBI), report on behalf of a larger collaboration: We observed the optical afterglow candidate (Xin et al., GCN 39380; Magnani et al., GCN 39382; see also Kennea et al., GCN 39379) of the SVOM/ECLAIRs GRB 250219A (Daigne et al., GCN 39376). Observations were carried out using the ALFOSC instrument mounted on the Nordic Optical Telescope (NOT). We obtained 3 x 300 s Sloan r-band frames at a median time of 10.16 hr post-burst and 5 x 200 s Sloan z-band frames at a median time of 10.46 hr post-burst. In the stacked r-band image, the afterglow is weakly detected, at coordinates R.A. (J2000) = 11:33:29.18 Dec. (J2000) = +22:42:21.85 with an uncertainty of ~0.3 arcsec, which is consistent with the SVOM/VT counterpart position (Xin et al, GCN 39380). The source had r ~ 23.6 +/- 0.3 mag (AB), calibrated against nearby objects from the Pan-STARRS catalog. The decay between the NOT and the SVOM/VT epochs (see also Magnani et al., GCN 39382) confirms the source is the afterglow of the burst. The source is not detected in the stacked z-band image, down to a limiting magnitude of z ~ 22.2 mag (AB), again calibrated against Pan-STARRS. View this GCN Circular online at https://gcn.nasa.gov/circulars/39383. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37393] GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
by GCN Circulars 20 Feb '25

20 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39382 SUBJECT: GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart DATE: 25/02/20 08:17:18 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Francesco Magnani (CPPM), Alan M. Watson (UNAM), Sarah Antier (OCA), Jean-Grégoire Ducoin (CPPM), Diego López-Cámara (UNAM), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the SVOM/ECLAIRs GRB 250219A (Daigne et al., GCN Circ. 39376) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-02-20 05:19 to 07:41 UTC (13.47 to 15.85 hours after the trigger) and obtained 90 minutes of exposure in the i filter. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1. Our photometry is in the AB system and is not corrected for Galactic extinction. At the position of the optical afterglow found by Xin et al. (GCN Circ. 39380), close to the uncataloged Swift/XRT source reported by Kennea et al. (GCN Circ. 39379), we detect a source with i = 23.53 +/- 0.21 We cannot yet confirm fading, as none of the previously reported photometry is in the i filter (Xin et al., GCN Circ. 39380; Lagioia et al., GCN Circ. 39381). Further observations are planned. 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/39382. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37392] GRB 250219A: 1.6m Mephisto optical upper limits
by GCN Circulars 20 Feb '25

20 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39381 SUBJECT: GRB 250219A: 1.6m Mephisto optical upper limits DATE: 25/02/20 05:23:35 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Edoardo P. Lagioia, Yu Pan, Xiangkun Liu, Yaosong Yu, Guowang Du, Brajesh Kumar, Yuan Fang, Jinghua Zhang, Xinlei Chen, Xingzhu Zou, Yuanpei Yang (all SWIFAR, YNU), Xuhui Han, Pinpin Zhang, Liping Xin, Chao Wu, Jianyan Wei (all NAOC), Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team: The field of GRB 250219A detected by SVOM/ECLAIRs (Daigne et al., GCN 39376) and followed-up by Swift-XRT (Kennea et al. GCN 39379) was observed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. Simultaneous uvgr band photometric observations were conducted starting from 17:08:52 2025-02-19 UT (~1.26 hr after the trigger) and 4 frames with 120s exposure times were taken. There is no detection of the optical candidate (Xin et al. GCN 39380) in the stacked images of uvgr bands. The preliminary photometry and 3 sigma upper limits are listed below. Start_Time(UT) | Band | Exp(s) | LimMag (AB) ---------------------------|--------|------------ 2025-02-19T17:18:46 | u | 120*4 | >22.4 2025-02-19T17:08:52 | v | 120*4 | >22.2 2025-02-19T17:18:46 | g | 120*4 | >22.8 2025-02-19T17:08:52 | r | 120*4 | >22.8 ------------------------------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21. ------------------------------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/39381. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37391] GRB 250219A: SVOM/VT optical counterpart
by GCN Circulars 20 Feb '25

20 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39380 SUBJECT: GRB 250219A: SVOM/VT optical counterpart DATE: 25/02/20 04:10:03 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> L.P. Xin, Y.L. Qiu, H.L. Li, C. Wu, Z.H. Yao, Y. N. Ma, X.H. Han, H.B. Cai, J. Wang, Y. Xu, J.Y. Wei (NAOC), R.Z. Li(YNAO), F. Daigne, M. Gnaoui (IAP) report on behalf of the SVOM team: The SVOM/VT conducted a ToO follow-up observations of the GRB 250219A (Daigne et al., GCN 39376) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. With the X band downlinked data, an uncatalogued optical source was clearly detected within the errorbox of Swift/XRT (Kennea et al., GCN 39379) in VT_R and VT_B stacked images, compared to the DESI catalogues. The position is RA= 173.37166 deg, DEC= 22.70598 deg, J2000, corresponds to RA = 11:33:29.2 DEC = +22:42:21.5 Error=0.5 arcsec The source is brightening at the first phase during our observations and the brightness was estimated to be 22.1+/-0.2 mag in AB magnitude in VT_R, and 23.3+/-0.3 mag in AB magnitude in VT_B, at the mid time of 6.71 hours post the burst, with an exposure time of 16*100 seconds. More deep follow-ups are encouraged. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/39380. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37390] GRB 250219A: Swift-XRT observations
by GCN Circulars 20 Feb '25

20 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39379 SUBJECT: GRB 250219A: Swift-XRT observations DATE: 25/02/20 01:07:10 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J. A. Kennea (PSU), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected burst GRB 250219A, collecting 323 s of Photon Counting (PC) mode data between T0+4.9 ks and T0+11.3 ks. One uncatalogued X-ray source has been detected within the estimated 3-sigma SVOM/ECLAIRs error region (557 arcsec), it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below: Source 1: RA (J2000.0): 173.3707 = 11:33:28.97 Dec (J2000.0): +22.7056 = +22:42:20.2 Error: 5.2 arcsec (radius, 90% conf.) Count-rate: 0.072 +/- 0.018 ct s^-1 Distance: 317 arcsec from SVOM/ECLAIRs position. Flux: (2.19 +/- 0.54)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021785. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39379. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37389] LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39378 SUBJECT: LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations DATE: 25/02/19 22:58:12 GMT FROM: Andrey Bogomolov at Moscow State University <aabboogg(a)srd.sinp.msu.ru> A. Bogomolov, V. Bogomolov, A. Iyudin, S. Svertilov. on behalf of the MSU “Sozvezdie-270” team, report: At the event time (2025-02-06 21:25:30 UTC) of S250206dm (GCN circulars #39175; #39178; #39231) two cubesats of the Moscow University project “Constellation-270” [1] were operating. These are Avion (the DeCoR-1 and DeCoR-2 instruments) and Arcticsat (the DeCoR-2 instrument). The analysis of monitoring data with the available time resolution of ~1 s did not reveal a significant increase in the count rate of all detectors in the time interval 21:22-21:30 UTC. The following 3-sigma upper limits on the flux were obtained (in units of 10^-7 erg/s/cm^2) for the timescales 1s and 5s. Satellite Energy Range Upper Limit(1s) Upper Limit(5s) Avion 30-500 keV 2.3 1.0 Arcticsat 50-500 keV 1.1 0.5 In the calculations we assumed the following source coordinates: RA=38°, Dec=53° (see GCN circulars #39231, #39261) Avion and Arcticsat are the cubesats of the Moscow University project “Constellation-270” [1] launched on 2023 June 27 (Avion) and on 2024 November 5 (Arcticsat). The payload of both cubesats is a set of scintillation gamma-ray detectors DeCoR [2], the energy range is >30 keV (Avion) and >50 keV (Arcticsat), the time resolution is 0.5s (Avion) and 1 s (Arcticsat). [1] Svertilov et al. 2023 https://link.springer.com/chapter/10.1007/978-3-031-50248-4_21 [2] Bogomolov et al. 2022 Universe 8, 282 https://www.mdpi.com/2218-1997/8/5/282 View this GCN Circular online at https://gcn.nasa.gov/circulars/39378. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37388] GRB 250219A: Swift ToO observations
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39377 SUBJECT: GRB 250219A: Swift ToO observations DATE: 25/02/19 17:16:31 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the SVOM/ECLAIRs GRB 250219A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021785 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the SVOM/ECLAIRs event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39377. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37387] GRB 250219A: SVOM detection of a burst
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39376 SUBJECT: GRB 250219A: SVOM detection of a burst DATE: 25/02/19 16:56:22 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> F. Daigne, M. Gnaoui (IAP), N. Dagoneau (CEA), S. Guillot, M. Brunet (IRAP), C.W. Wang (IHEP) on behalf of the SVOM mission team. At 2025-02-19T15:52:48 UTC (Tb) SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250219A (SVOM burst-id sb25021904). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), from which we received 2 alerts. IMT provided the alert with the best signal-to-noise-ratio (SNR) of 14.57 in the [5-8] keV energy band over a time window of 40.96 seconds starting at Tb. The light curve showed a first episode of about 10 s, followed by a possibly related second episode 130 s later, with a duration of about 50 s. The localization of the best alert is R.A., Dec 173.278, 22.684 degrees: RA (J2000) = 11h33m06.69s Dec (J2000) = 22d41m01.24s with a 90% C.L. radius of 5.65 arcmin (including systematic error of 2 arcmin added in quadrature). No immediate slew was performed on this burst. A SVOM ToO has been requested. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. The Burst Advocate (BA) on shift for this burst is Frédéric Daigne: daigne(a)iap.fr. Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/39376. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37386] Konus-Wind detection of GRB 250215A / EP250215a
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39375 SUBJECT: Konus-Wind detection of GRB 250215A / EP250215a DATE: 25/02/19 15:45:03 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 250215A / EP250215a (Fermi-GBM detection: The Fermi GBM team, GCN 39327; Scotton and Meegan, GCN 39342; EP-WXT detection: Wang et al., GCN 39329; INTEGRAL-SPI-ACS detection: Barria et al., GCN 39331; AstroSat-CZTI detection: Tembhurnikar et al., GCN 39334; SVOM/GRM detection: Zheng et al., GCN 39335) triggered Konus-Wind at T0=09130.387 s UT (02:32:10.387). The burst light curve shows a multipeaked structure which starts at ~T0-14 s and has a total duration of ~22 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/GRB250215_T09130/ As observed by Konus-Wind, the burst had a fluence of 8.33(-1.97,+2.51)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+0.054 s, of 5.12(-1.37,+1.66)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Since a major part of the burst emission was detected before the trigger time and the burst shows a minor spectral evolution, we use the spectrum measured from T0 to T0+8.448 s to estimate the total burst fluence. This spectrum is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.03(-0.54,+0.69), the high energy photon index beta = -2.31(-1.22,+0.30), the peak energy Ep = 130(-36,+80) keV (chi2 = 80/97 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.14(-0.74,+3.47), the high energy photon index beta = -2.35(-0.68,+0.29), the peak energy Ep = 118(-51,+53) keV (chi2 = 18/17 dof). Assuming the redshift z=4.61 (Sanchez-Ramirez et al., GCN 39343) 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 3.35(-0.79,+1.01)x10^53 erg, the peak luminosity L_iso is 1.15(-0.31,+0.37)x10^54 erg/s, the rest-frame peak energy of the time-averaged spectrum Ep,i,z is 660(-250,+298) keV. With the obtained estimates, GRB 250215A is inside 68% prediction band for the 'Amati' and 90% - for 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/GRB250215_T09130/GRB250215A_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/39375. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37385] SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39374 SUBJECT: SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability DATE: 25/02/19 14:04:46 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Damien Dornic (CPPM), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Benjamin Schneider (LAM) report: We imaged the field of SVOM/ECLAIRs trigger sb25021804 (Wang et al., GCN 39363) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-02-19 06:23 to 09:00 UTC (23.1 to 25.7 hours after the trigger) and obtained 100 minutes of exposure in the r filter. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1. Our photometry is in the AB system and is not corrected for Galactic extinction. For the X-ray bright QSO WISEA J130010.60+280749.7, suggested by Eyles-Ferris et al. (GCN Circ. 39372) as a possible counterpart of the ECLAIRs source, we measure a magnitude of r = 19.95 +/- 0.01 In our observation on the previous night, reported in de Ugarte Postigo et al. (GCN Circ. 39364), we measure i = 19.98 +/- 0.04 Our magnitudes are about 0.3 magnitudes above the mean magnitudes reported in SDSS DR6 and PanSTARRS DR1. This confirms the excess reported by Eyles-Ferris et al. (GCN Circ. 39372) and strengthens their suggestion that this QSO might be related to the SVOM trigger. 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/39374. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37384] GRB 250217C: Swift-XRT observations
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39373 SUBJECT: GRB 250217C: Swift-XRT observations DATE: 25/02/19 13:51:26 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A.P. Beardmore (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), M. A. Williams (PSU), J.P. Osborne (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the IPN-detected burst GRB 250217C in a series of observations tiled on the sky. The total exposure time is 3.5 ks, distributed over 7 tiles; the maximum exposure at a single sky location in the tiling was 1.2 ks. The data were collected between T0+69.9 ks and T0+98.0 ks, and are entirely in Photon Counting (PC) mode. No uncatalogued X-ray sources have been detected. The 3-sigma upper limit in the field (not including the regions where the tiles overlap) ranges from ~0.01 to ~0.03 ct s^-1, corresponding to a 0.3-10 keV observed flux of 5.3e-13 to 1.3e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum). Three previously-catalogued X-ray sources have been detected, however their status as catalogued objects makes them unlikely to be the afterglow. The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00133. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39373. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37383] SVOM/sb25021804: QSO variability in Liverpool Telescope observations
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39372 SUBJECT: SVOM/sb25021804: QSO variability in Liverpool Telescope observations DATE: 25/02/19 11:37:18 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris, P. T. O’Brien and R. L. C. Starling (U of Leicester) report on behalf of a larger collaboration: We observed the field of the SVOM/ECLAIRs transient sb25021804 (Wang et al., GCN 39363) in four pointings covering ~87% of the error area using the IO:O on the 2m Liverpool Telescope. We obtained 4x150s exposures per pointing in the SDSS g’ filter starting at 2025-02-19 04:59:09 UT, approximately 21.7 hours after the SVOM/ECLAIRs detection. We performed image subtraction on the stacked images using reference images from Pan-STARRS. We identify a residual at RA, Dec 195.044, 28.130 which corresponds to the X-ray bright QSO WISEA J130010.60+280749.7, about 3.4 arcmin from the SVOM ECLAIRs position reported by Wang et al., GCN 39363. We performed PSF photometry on the stacked image and find g’ = 20.09 +/- 0.11 calibrated to Pan-STARRS and not corrected for Galactic extinction. This is ~0.5 mag brighter than the magnitude catalogued in Pan-STARRS DR2 and we suggest sb25021804 is related to this variability. We find no other obvious residuals in the subtracted images to a 3-sigma limiting magnitude of ~21.5. View this GCN Circular online at https://gcn.nasa.gov/circulars/39372. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37382] GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39371 SUBJECT: GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart DATE: 25/02/19 07:20:09 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Antonio de Ugarte Postigo (LAM), Eleonora Troja (U Roma), Rosa L. Becerra (U Roma), Simone Dichiara (PSU), 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), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Benjamin Schneider (LAM) report: We imaged the IPN 3-sigma error box of GRB 250217C (Fermi GBM Team, GCN Circ. 39357, Tembhurnikar et al., GCN Circ. 39359, Kozyrev et al., GCN Circ. 39365) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We used three pointings that, combined with the 26 arcmin field of COLIBRÍ/DDRAGO, cover more than 95% of the IPN error box. We observed from 2025-02-19 02:51 to 04:18 UTC (27.0 to 28.4 hours after the trigger) and obtained 20 minutes of exposure at each pointing in the i filter. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our photometry is not corrected for Galactic extinction. We do not detect any likely optical counterpart to a 5-sigma limit of i > 22.7 Our non-detections are consistent with the shallower limits reported by Becerra et al. (GCN Circ. 39370) and with the lack of a bright X-ray candidate counterpart in the tiled Swift/XRT ToO observations reported by Evans et al. (GCN Circ. 39368). 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/39371. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37381] GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39370 SUBJECT: GRB 250217C: DDOTI Upper Limits on the Optical Afterglow DATE: 25/02/19 05:38:12 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Simone Dichiara (Penn State University), Eleonora Troja (U Roma), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), and Margarita Pereyra (UNAM) report: We observed the field of GRB 250217C detected by Fermi/GBM (Fermi GBM Team et al., GCN 39357), AstroSat CZTI (Tembhurnikar et al., GCN 39359), and IPN (Kozyrev et al., GCN 39365), with the DDOTI/OAN wide-field imager at the Observatorio Astronomico Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2025-02-19 UTC. DDOTI observed the whole IPN error box reported by Kozyrev et al. (GCN 39365) from 03:31 UTC to 04:37 UTC (from T+27.6 to T+28.7 hours after the event) with a total exposure of 48 minutes, down to a 5-sigma limiting magnitude of w = 21.1. Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogues, we detect no uncatalogued sources within the observed field to our 5-sigma limit. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/39370. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37380] GRB 250217C: SVOM/GRM observation
by GCN Circulars 19 Feb '25

19 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39369 SUBJECT: GRB 250217C: SVOM/GRM observation DATE: 25/02/19 03:52:28 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Shao-Lin Xiong, Yue Huang, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Frédéric Piron (LUPM), Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia, Sébastien Guillot (IRAP) report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a short burst GRB 250217C (sb25021704) at 2025-02-17T23:54:41.900 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #39357), AstroSat (M. Tembhurnikar et al., GCN #39359), Konus-Wind, HEND/Mars and INTEGRAL SPI-ACS (A.S. Kozyrev et al., GCN #39365). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-pulses with a T90 of about 0.42 +0.07/-0.22 seconds in the 15-5000 keV. The time-averaged spectrum from T0-0.2 to T0+0.2 s could be fit by a Band function with alpha = -0.61 +/- 0.3, beta = -1.87 +/- 0.07 and Epeak = 77 +20/-11 keV. The event fluence (10-1000 keV) in this time interval is (1.40 +/- 0.71)E-06 erg/cm^2. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250217C.png In addition, the position of this burst, as determined by Fermi/GBM (Fermi GBM Team, GCN #39357), is located at about 50 degrees from the SVOM optical axis, right at the edge of the ECLAIRs field of view. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Chen-Wei Wang (IHEP) (cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/39369. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37379] GRB 250217C: Tiled Swift observations
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39368 SUBJECT: GRB 250217C: Tiled Swift observations DATE: 25/02/18 19:30:39 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the IPN GRB 250217C. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00133 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the IPN event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39368. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37378] GRB 250217C: Fermi GBM Observation
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39367 SUBJECT: GRB 250217C: Fermi GBM Observation DATE: 25/02/18 18:55:40 GMT FROM: Jacob Smith at Fermi-GBM Team <jrs0118(a)uah.edu> Jacob Smith (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: At 23:54:41.80 UT on 17 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250217C (trigger 761529286/250217996). which was also detected by AstroSat (M. Tembhurnikar, et al. 2025, GCN 39359) and IPN triangulation (A.S. Kozyrev, et al. 2025, GCN 39365). The Fermi GBM on-ground location is consistent with the IPN triangulation. The angle from the Fermi LAT boresight is 100 degrees. The GBM light curve consists of a double emission episode with a duration (T90) of about 0.35 s (50-300 keV). The time-averaged spectrum from T0-0.06 to T0+0.38 s is best fit by a Band function with Epeak = 85 +/- 13 keV, alpha = -0.2 +/- 0.3, and beta = -1.83 +/- 0.04. The event fluence (10-1000 keV) in this time interval is (1.68 +/- 0.05)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.0 s in the 10-1000 keV band is 62 +/- 3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39367. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37377] GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39366 SUBJECT: GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61 DATE: 25/02/18 17:28:03 GMT FROM: Remo Ruffini at ICRA <ruffini(a)icra.it> R. Ruffini, D. Berkimbayev, G. Vereshchagin, R. F. Mohideen Malik, N. Shynggyskhan, M.T. Mirtorabi, J.A. Rueda, Y. Wang, S.S. Xue, on behalf of the ICRANet team, report: GRB 250215A / EP250215A was detected by Fermi (GCN 39327), Einstein Probe (GCN 39329), and SVOM (GCN 39333) at a redshift of z = 4.61 (GCN 39343). The burst duration is 2.3 s in the rest frame, corresponding to T_{90} = 13.4 s in the observer's frame (GCN 39342). The isotropic energy release is 3 \times 10^{53} erg, consistent with a BdHN I classification. This event shares similarities with GRB 220101A (GCN 37964), GRB 221009A (GCN 32828), and GRB 240825A (GCN 37536). Extended follow-up multi-wavelength observations are encouraged to fully characterize the BdHN I episodes: optical data for pulsar identification, X-ray observations to track the afterglow evolution, and GeV measurements to constrain the black hole energy. View this GCN Circular online at https://gcn.nasa.gov/circulars/39366. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37376] IPN triangulation of GRB 250217C (short)
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39365 SUBJECT: IPN triangulation of GRB 250217C (short) DATE: 25/02/18 16:19:04 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, G. Waratkar, J.Joshi, V. Bhalerao, D. Bhattacharya, and S. Vadawale, on behalf of the Astrosat-CZTI team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The bright, short-duration GRB 250217C (Fermi-GBM detection: The Fermi GBM team, GCN 39357; AstroSat-CZTI detection: Tembhurnikar et al., GCN 39359) was detected by Fermi (GBM trigger 761529286), AstroSat (CZTI), Konus-Wind, INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND) at about 86082 s UT (23:54:42). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 122.164 (08h 08m 39s) +45.257 (+45d 15' 24") Corners: 121.397 (08h 05m 35s) +45.429 (+45d 25' 44") 122.008 (08h 08m 02s) +45.505 (+45d 30' 17") 122.915 (08h 11m 40s) +45.069 (+45d 04' 08") 122.314 (08h 09m 15s) +45.007 (+45d 00' 27") --------------------------------------------- The error box area is 818 sq. arcmin, and its maximum dimension is 1.13 deg (the minimum one is 17.6 arcmin). The Sun distance was 137 deg. This localization may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi-GBM (GCN 39357) localization. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB250217_T86086/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. Swift-XRT ToO has been submitted. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/39365. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37375] Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39364 SUBJECT: Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart DATE: 25/02/18 16:18:24 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Benjamin Schneider (LAM) report: We imaged the field of SVOM trigger sb25021804 (Wang et al., GCN 39363) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. The coordinates of this trigger are about 6 arcmin north of the galaxy NGC 4889, the brightest galaxy in the Coma Cluster (Abell 1656). The uncertainty radius is 10.4 arcmin, and so includes much of the central region of the cluster. We observed from 2025-02-18 09:44 UTC to 11:51 UTC (2.71 to 4.52 hours after the trigger) and obtained 53 minutes of exposure in the i filter through patchy clouds and with high winds. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our photometry is not corrected for Galactic extinction. Our image reaches an AB 5-sigma limiting magnitude of i > 21.7 We have performed image subtraction and see no obvious counterpart. The detection of a counterpart with Swift/XRT or SVOM/MXT would facilitate searches for a faint counterpart. 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/39364. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37374] SVOM/sb25021804: SVOM detection of a long X-ray transient
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39363 SUBJECT: SVOM/sb25021804: SVOM detection of a long X-ray transient DATE: 25/02/18 15:56:15 GMT FROM: Stéphane Schanne at CEA Paris-Saclay/IRFU <s.schanne(a)cea.fr> C.-W. Wang, W.-J. Tan (IHEP), D. Turpin, S. Schanne, N. Dagoneau (CEA) report on behalf of the SVOM mission team: The SVOM/ECLAIRs telescope triggered and located a long duration soft X-ray transient (SVOM burst-id sb25021804) starting at 2025-02-18T07:20:27 UTC (Tb). The following trigger information was received on the ground with low-latency by the SVOM VHF Alert Network. The burst was detected by the Image Trigger (IMT) and only 1 alert was produced with a signal-to-noise ratio of 7.56 in the 5-8 keV energy band over a time window of 22 minutes starting at Tb. The sub-image transmitted shows a clean point-like source. The localization of the alert is R.A., Dec = 195.020, 28.078 degrees: RA (J2000) = 13h00m04.93s Dec (J2000) = 28d04m39.02s with a 90% C.L. radius of 10.4 arcmin (including systematic error of 2 arcmin added in quadrature). We notice that this error-box contains several X-ray sources which could produce such a transient, including 4 AGNs and the ULX-candidate labelled "[SRW2012] Src. 6" in Simbad, located at 9.2 arcmin distance. This trigger did not reach the slew threshold, hence no automatic slew was performed. A SVOM ToO has been scheduled and a Swift XRT ToO has been requested. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. The Burst Advocate (BA) on shift for this burst is Chen-Wei Wang (IHEP) : cwwang(a)ihep.ac.cn Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/39363. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37373] GRB 250213A: Swift-XRT observations
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39362 SUBJECT: GRB 250213A: Swift-XRT observations DATE: 25/02/18 15:33:01 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), M. A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected burst GRB 250213A, collecting 3.3 ks of Photon Counting (PC) mode data between T0+26.1 ks and T0+50.5 ks. Three uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 2: RA (J2000.0): 112.5572 = 07:30:13.74 Dec (J2000.0): -19.9494 = -19:56:57.9 Error: 9.1 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (5.8 [+2.0, -1.6])e-3 ct s^-1 Distance: 578 arcsec from SVOM/ECLAIRs position. Flux: (4.2 [+1.4, -1.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 3: RA (J2000.0): 112.5390 = 07:30:9.37 Dec (J2000.0): -20.1093 = -20:06:33.6 Error: 6.4 arcsec (radius, 90% conf.) Count-rate: (3.4 [+1.4, -1.2])e-3 ct s^-1 Distance: 175 arcsec from SVOM/ECLAIRs position. Flux: (6.4 [+2.7, -2.2])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 112.2781 = 07:29:6.75 Dec (J2000.0): -20.0889 = -20:05:19.9 Error: 6.3 arcsec (radius, 90% conf.) Count-rate: (3.0 [+1.6, -1.2])e-3 ct s^-1 Distance: 712 arcsec from SVOM/ECLAIRs position. Flux: (5.9 [+3.1, -2.3])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) A catalogued source was also detected. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021777. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39362. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37372] LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39361 SUBJECT: LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations DATE: 25/02/18 11:24:47 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI, HSE), A. Volnova (IKI), E. Klunko (ISTP) report on behalf of the IKI GRB-FuN collaboration: We observed the fields of 8 GLADE+ galaxies contained in the 50% probability volume traced by the LIGO/Virgo/KAGRA in the latest Bilby.offline1.multiorder.fits skymap file for S250206dm (LIGO Scientific Collaboration, GCN 39175; LIGO Scientific Collaboration, GCN 39184). The observations were carried out with the 1.5-meter telescope of the Sayan Solar Observatory located at Mondy, Buryatia. The series of the 3*120 sec exposures in the R-filter were taken on epochs of Feb. 12 and Feb. 14. We performed subtraction of the Feb.14 stacked images from the ones taken on Feb.12. Our preliminary analysis of the residual difference images does not reveal any prominent optical transient located in the vicinity of the observed GLADE+ galaxies. The preliminary 3-sigma upper limits on the subtracted images are as follows: Galaxy UTstart MJDmid Exp. Filter UL FWHM ------ ------- ------ ---- ------ ---- ---- J021712_47_+532137_62 2025-02-12T14:32:26 60718.60795 3*120 R 19.7 2.9 J021738_38_+521958_56 2025-02-12T14:05:11 60718.58902 3*120 R 20.6 3.1 J021815_59_+530110_02 2025-02-12T14:25:32 60718.60315 3*120 R 20.3 2.9 J021826_85_+523810_42 2025-02-12T14:11:41 60718.59354 3*120 R 19.8 3.4 J021830_02_+524021_45 2025-02-12T14:18:37 60718.59835 3*120 R 19.8 3.0 J022347_90_+514635_27 2025-02-12T13:58:32 60718.58440 3*120 R 20.2 2.8 J022352_96_+513006_26 2025-02-12T13:44:43 60718.57481 3*120 R 20.3 2.8 J022405_82_+513240_21 2025-02-12T13:51:37 60718.57960 3*120 R 20.4 3.0 * 60712.89271 MJD -- The LIGO trigger time for S250206dm The photometry is based on nearby stars from the USNO-B1.0 catalog (R2 magnitudes) and has not been corrected for the Galactic extinction. The further analysis is ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/39361. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37371] GRB 250216A: AstroSat CZTI detection
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39360 SUBJECT: GRB 250216A: AstroSat CZTI detection DATE: 25/02/18 05:55:34 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> M. Tembhurnikar (IUCAA), G. Waratkar (IITB), J. Joshi (IUCAA), 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 a faint detection of GRB 250216A which was also detected by Fermi/GBM (Fermi-GBM Team, GCN Circ. 39347). Inspection of INTEGRAL/SPI-ACS data also showed the detection of the burst. Due to the likely hard nature of the burst, we don’t see any detection in the CZT detectors (20-200 keV). The source was faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range and we see only the initial short spike from the Fermi/GBM lightcurve. The light curve peaks at 2025-02-16 20:20:42.4 UTC. The measured peak count rate associated with the burst is 273 (+63, -65) counts/s above the background in the combined data of all quadrants, with a total of 399 (+207, -194) counts. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it. 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/39360. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37370] GRB 250217C: AstroSat CZTI detection of a short burst
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39359 SUBJECT: GRB 250217C: AstroSat CZTI detection of a short burst DATE: 25/02/18 05:25:45 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> M. Tembhurnikar (IUCAA), G. Waratkar (IITB), J. Joshi (IUCAA), 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 short-duration GRB 250217C which was also detected by Fermi (Fermi-GBM Team, GCN Circ. 39357). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-02-17 23:54:41.85 UTC. The measured peak count rate associated with the burst is 1090 (+213, -122) counts/s above the background in the combined data of three quadrants (out of four), with a total of 296 (+53, -56) counts. The local mean background count rate was 273 (+15, -18) counts/s. Using cumulative rates, we measure a T90 of 0.35 (+0.39, -0.09) s. The source was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-02-17 23:54:41.14 UTC. The measured peak count rate associated with the burst is 358 (+63, -67) counts/s above the background in the combined data of all quadrants, with a total of 309 (+169, -171) counts. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it. 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/39359. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37369] Fermi GRB 250217C: Global MASTER-Net observations report
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39358 SUBJECT: Fermi GRB 250217C: Global MASTER-Net observations report DATE: 25/02/18 00:16:58 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 250217C ( Fermi GBM team, GCN 39357) errorbox 588 sec after notice time and 626 sec after trigger time at 2025-02-18 00:05:08 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 74 deg. The sun altitude is -42.9 deg. The galactic latitude b = 38 deg., longitude l = 191 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2781342 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 657 | 2025-02-18 00:05:08 | MASTER-SAAO | (08h 45m 43.52s , +32d 50m 06.0s) | C | 60 | 17.9 | 717 | 2025-02-18 00:05:08 | MASTER-SAAO | (08h 45m 43.52s , +32d 50m 05.9s) | C | 180 | 18.5 | Coadd 736 | 2025-02-18 00:06:27 | MASTER-SAAO | (08h 45m 43.62s , +32d 50m 10.7s) | C | 60 | 17.6 | 815 | 2025-02-18 00:07:46 | MASTER-SAAO | (08h 45m 43.81s , +32d 50m 10.7s) | C | 60 | 17.5 | 894 | 2025-02-18 00:09:05 | MASTER-SAAO | (08h 45m 44.00s , +32d 50m 14.7s) | C | 60 | 17.6 | 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/39358. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37368] GRB 250217C: Fermi GBM Final Real-time Localization
by GCN Circulars 18 Feb '25

18 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39357 SUBJECT: GRB 250217C: Fermi GBM Final Real-time Localization DATE: 25/02/18 00:05:15 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 23:54:41 UT on 17 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250217C (trigger 761529286.801804 / 250217996). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 131.6, Dec = 32.9 (J2000 degrees, equivalent to J2000 08h 46m, 32d 53'), with a statistical uncertainty of 5.5 degrees. The angle from the Fermi LAT boresight is 100.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39357. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37367] IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 17 Feb '25

17 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39356 SUBJECT: IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/02/17 22:56:25 GMT FROM: Sam Hori at IceCube/U Wisc-Madison <sahori(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-Cascade 250215A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/140500_12724443.amon) in a time range of 1000 seconds centered on the alert event time (2025-02-15 10:57:22.720 UTC to 2025-02-15 11:14:02.720 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-Cascade 250215A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-Cascade 250215A ranges from 1.4e-01 to 1.9e+00 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 3e+02 GeV and 1e+06 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-02-14 11:05:42.720 UTC to 2025-02-16 11:05:42.720 UTC). In this case, we report a p-value of 0.56, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-Cascade 250215A ranges from 1.6e-01 to 1.9e+00 GeV cm^-2 in a 2 day time window. 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] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/39356. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37366] LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
by GCN Circulars 17 Feb '25

17 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39355 SUBJECT: LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7 DATE: 25/02/17 20:20:56 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex(a)gmail.com> A. Pozanenko (IKI, HSE), A. Volnova (IKI), N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO) report on behalf of IKI GRB-FuN collaboration: We continue to observe galaxies from the NED/GLADE+ catalogs in the localization volume S250206dm (LIGO Scientific Collaboration, GCN 39175; LIGO Scientific Collaboration, GCN 39184). We observed several galaxies with AS-32 telescope of the Abastumani Observatory (AbAO) in the R-filter. The observations consist of 3 exposures in R-filter of each galaxy in the on Feb., 12 and Feb. 16. In the first epoch of observations near the galaxy WISEA J021210.14+514821.7 we clearly detected an optical source which is not present in the PS1 catalog. The source is visible in each of the 3 exposures. The source is not detected in the following epoch on February 16. Preliminary photometry of stacked images is the following Date |UTstart |t-T0* |MJD_mid |Exp. |Filter|OT |Err |UL |FWHM | |(mid, days)| |(n*s) | | | |(3sigma)|" ---------------------------------------------------------------------------- 2025-02-12|15:46:10| 5.76573|60718.65844| 3*60 |R |18.15|0.21|19.0 |3.1 2025-02-16|15:57:48| 9.77361|60722.66632| 3*60 |R | n/d |n/d |19.1 |3.0 * - T0 = 21:25:30.439 UTC LIGO trigger time of S250206dm Photometry is based on nearby stars from USNO-B1.0: ID RA Dec R2 1418-00067499 02:12:12.126 +51:49:52.59 14.68 1418-00067498 02:12:12.025 +51:48:41.88 14.94 1418-00067549 02:12:18.069 +51:48:21.33 13.93 The source coordinates are (J2000) 02:12:10.17 +51:48:21.54, and the offset from the center of the galaxy is 6.2", which is equivalent to 11 kpc at a luminosity distance of DL = 457 Mpc (GLADE+). We have not observed this galaxy before, so we cannot say anything about the nature of this source and further observations and analysis of further observations of this galaxy are needed. View this GCN Circular online at https://gcn.nasa.gov/circulars/39355. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37365] Fermi GRB 250217A: Global MASTER-Net observations report
by GCN Circulars 17 Feb '25

17 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39354 SUBJECT: Fermi GRB 250217A: Global MASTER-Net observations report DATE: 25/02/17 19:16:43 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 250217A ( Fermi GBM team, GCN 39350) errorbox 37460 sec after notice time and 37513 sec after trigger time at 2025-02-17 18:12:39 UT, with upper limit up to 19.2 mag. Observations started at twilight. The observations began at zenith distance = 77 deg. The sun altitude is -10.1 deg. The galactic latitude b = 46 deg., longitude l = 242 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2780694 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 37544 | 2025-02-17 18:12:39 | MASTER-SAAO | (10h 16m 22.94s , +03d 14m 00.2s) | C | 60 | 16.0 | 37623 | 2025-02-17 18:13:58 | MASTER-SAAO | (10h 24m 17.42s , +03d 13m 24.7s) | C | 60 | 16.1 | 37703 | 2025-02-17 18:15:18 | MASTER-SAAO | (10h 15m 33.52s , -00d 34m 28.6s) | C | 60 | 16.7 | 37782 | 2025-02-17 18:16:37 | MASTER-SAAO | (10h 23m 28.04s , -00d 35m 21.2s) | C | 60 | 16.7 | 37861 | 2025-02-17 18:17:56 | MASTER-SAAO | (10h 15m 38.07s , +01d 18m 56.8s) | C | 60 | 17.2 | 38020 | 2025-02-17 18:20:35 | MASTER-SAAO | (10h 00m 23.97s , +01d 20m 09.2s) | C | 60 | 17.7 | 38100 | 2025-02-17 18:21:55 | MASTER-SAAO | (10h 08m 18.74s , +01d 19m 21.9s) | C | 60 | 17.5 | 38179 | 2025-02-17 18:23:14 | MASTER-SAAO | (10h 23m 30.96s , +01d 20m 37.8s) | C | 60 | 17.5 | 38436 | 2025-02-17 18:27:32 | MASTER-SAAO | (10h 16m 23.35s , +03d 12m 29.7s) | C | 60 | 18.3 | 38516 | 2025-02-17 18:28:51 | MASTER-SAAO | (10h 24m 20.53s , +03d 14m 07.8s) | C | 60 | 18.4 | 38595 | 2025-02-17 18:30:11 | MASTER-SAAO | (10h 15m 29.71s , -00d 35m 07.5s) | C | 60 | 18.1 | 38675 | 2025-02-17 18:31:30 | MASTER-SAAO | (10h 23m 32.72s , -00d 33m 44.1s) | C | 60 | 18.3 | 38754 | 2025-02-17 18:32:49 | MASTER-SAAO | (10h 15m 31.84s , +01d 19m 27.7s) | C | 60 | 18.5 | 38913 | 2025-02-17 18:35:29 | MASTER-SAAO | (10h 00m 24.62s , +01d 19m 09.7s) | C | 60 | 18.8 | 38993 | 2025-02-17 18:36:48 | MASTER-SAAO | (10h 08m 18.72s , +01d 18m 19.4s) | C | 60 | 18.7 | 39072 | 2025-02-17 18:38:07 | MASTER-SAAO | (10h 23m 37.02s , +01d 18m 38.7s) | C | 60 | 18.5 | 39152 | 2025-02-17 18:39:27 | MASTER-SAAO | (10h 16m 19.26s , +03d 14m 18.3s) | C | 60 | 19.1 | 39231 | 2025-02-17 18:40:46 | MASTER-SAAO | (10h 24m 20.18s , +03d 13m 05.3s) | C | 60 | 19.0 | 39311 | 2025-02-17 18:42:06 | MASTER-SAAO | (10h 15m 32.19s , -00d 34m 00.4s) | C | 60 | 18.8 | 39390 | 2025-02-17 18:43:25 | MASTER-SAAO | (10h 23m 25.53s , -00d 34m 22.5s) | C | 60 | 18.9 | 39469 | 2025-02-17 18:44:45 | MASTER-SAAO | (10h 15m 30.42s , +01d 20m 26.2s) | C | 60 | 18.9 | 39549 | 2025-02-17 18:46:04 | MASTER-SAAO | (10h 00m 24.19s , +01d 19m 07.1s) | C | 60 | 19.0 | 39628 | 2025-02-17 18:47:23 | MASTER-SAAO | (10h 08m 16.84s , +01d 18m 16.3s) | C | 60 | 19.0 | 39707 | 2025-02-17 18:48:42 | MASTER-SAAO | (10h 23m 37.34s , +01d 18m 48.5s) | C | 60 | 18.8 | 39786 | 2025-02-17 18:50:01 | MASTER-SAAO | (10h 16m 18.87s , +03d 14m 16.4s) | C | 60 | 19.1 | 39866 | 2025-02-17 18:51:21 | MASTER-SAAO | (10h 24m 19.85s , +03d 12m 56.8s) | C | 60 | 19.3 | 39945 | 2025-02-17 18:52:40 | MASTER-SAAO | (10h 15m 32.39s , -00d 33m 35.0s) | C | 60 | 18.8 | 40025 | 2025-02-17 18:54:00 | MASTER-SAAO | (10h 23m 25.44s , -00d 34m 24.6s) | C | 60 | 18.8 | 40104 | 2025-02-17 18:55:19 | MASTER-SAAO | (10h 15m 29.65s , +01d 20m 24.1s) | C | 60 | 18.9 | 40183 | 2025-02-17 18:56:38 | MASTER-SAAO | (10h 00m 23.35s , +01d 19m 05.3s) | C | 60 | 19.0 | 40263 | 2025-02-17 18:57:58 | MASTER-SAAO | (10h 08m 18.16s , +01d 18m 15.0s) | C | 60 | 18.9 | 40342 | 2025-02-17 18:59:17 | MASTER-SAAO | (10h 23m 35.53s , +01d 18m 36.5s) | C | 60 | 18.6 | 40421 | 2025-02-17 19:00:37 | MASTER-SAAO | (10h 16m 18.59s , +03d 14m 08.5s) | C | 60 | 19.1 | 40503 | 2025-02-17 19:01:58 | MASTER-SAAO | (10h 24m 19.63s , +03d 12m 48.3s) | C | 60 | 18.6 | 40582 | 2025-02-17 19:03:17 | MASTER-SAAO | (10h 15m 30.89s , -00d 33m 42.9s) | C | 60 | 18.5 | 40661 | 2025-02-17 19:04:37 | MASTER-SAAO | (10h 23m 24.65s , -00d 34m 26.8s) | C | 60 | 18.6 | 40741 | 2025-02-17 19:05:56 | MASTER-SAAO | (10h 15m 29.20s , +01d 20m 22.3s) | C | 60 | 18.7 | 40820 | 2025-02-17 19:07:15 | MASTER-SAAO | (10h 00m 21.50s , +01d 19m 04.6s) | C | 60 | 18.9 | 40900 | 2025-02-17 19:08:35 | MASTER-SAAO | (10h 08m 17.00s , +01d 18m 13.4s) | C | 60 | 18.8 | 40979 | 2025-02-17 19:09:54 | MASTER-SAAO | (10h 23m 35.03s , +01d 18m 55.5s) | C | 60 | 18.7 | 41058 | 2025-02-17 19:11:13 | MASTER-SAAO | (10h 16m 18.03s , +03d 14m 19.4s) | C | 60 | 19.1 | 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/39354. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37364] GRANDMA/OPD observations of GRB250215A
by GCN Circulars 17 Feb '25

17 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39353 SUBJECT: GRANDMA/OPD observations of GRB250215A DATE: 25/02/17 12:20:03 GMT FROM: Nidhal Guessoum at AUS, UAE <nguessoum(a)aus.edu> Leandro de Almeida (LNA), Nélio Sasaki (UEA-Parintins), Wagner Corradi (LNA), Felipe Navarete (LNA), Martin Masek (FZU), Nuha Manal Pattani (AUS), Shaikha Alshamsi (AUS), S. Antier (OCA/IJCLAB), P. Hello (IJCLAB), N. Guessoum (AUS), C. Andrade, M. Coughlin (UMN), P-A Duverne (APC), S. Karpov (FZU), T. Pradier (Unistra/IPHC), and D. Turpin (CEA-Saclay/Irfu), on behalf of Observatório do Pico dos Dias (OPD/LNA/Brazil) and the GRANDMA collaboration, began observations of GRB 250215A, initially detected by the Fermi GBM Team (GCN 39327). Based on the coordinates of the field center (RA=10:25:19.48, DEC=-27:41:54.00), we obtained 12 frames of 300 seconds each using the 0.6m telescope of OPD, starting on 2025-02-16 at 02:30:42.23 and ending at 07:43:29.39 UTC. The FOV of the stacked image is 10.5x10.5 arcmin with a pixel scale of 0.614 arcsec/pixel. We did not detect any candidate in our stacked images with an upper limit of I > 21.34 mag at 5-sigma, calibrated against several stars of the I/339 catalog (HSOY, Altmann et al, 2017). Our non-detection upper limit is similar to the results of Ducoin et al. (GCN 39344) with nothing brighter than 22.7 mag detected in r. Our results are also in slight discrepancy with the findings of Malesani et al. (GCN 39341). GRANDMA is a worldwide telescope network (http://grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). View this GCN Circular online at https://gcn.nasa.gov/circulars/39353. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37363] GRB 250217B: Fermi GBM Final Real-time Localization
by GCN Circulars 17 Feb '25

17 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39352 SUBJECT: GRB 250217B: Fermi GBM Final Real-time Localization DATE: 25/02/17 11:35:46 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 11:27:19 UT on 17 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250217B (trigger 761484444.589826 / 250217477). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 231.3, Dec = 34.9 (J2000 degrees, equivalent to J2000 15h 25m, 34d 53'), with a statistical uncertainty of 6.0 degrees. The angle from the Fermi LAT boresight is 121.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217477/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217477/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217477/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39352. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37362] The EP-WXT trigger 01709131775 is likely a flaring star
by GCN Circulars 17 Feb '25

17 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39351 SUBJECT: The EP-WXT trigger 01709131775 is likely a flaring star DATE: 25/02/17 08:09:25 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> C. Zhou (HUST), G. Y. Zhao (SYSU), T. C. Zheng (PMO, CAS), X. Pan, H. W. Pan (NAOC, CAS) report on behalf of the Einstein Probe team: The EP-WXT trigger (ID: 01709131775 ) on 2025-02-17 06:56:23 (UTC) is likely a stellar flare associated with a T Tauri star RX J0523.0-0850. The estimated flux of the flare is around 8.0 x 10^-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 2.2 x 10^32 erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with onboard 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/39351. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37361] GRB 250217A: Fermi GBM Final Real-time Localization
by GCN Circulars 17 Feb '25

17 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39350 SUBJECT: GRB 250217A: Fermi GBM Final Real-time Localization DATE: 25/02/17 07:57:49 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 07:47:25 UT on 17 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250217A (trigger 761471250.62418 / 250217325). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 154.9, Dec = 1.9 (J2000 degrees, equivalent to J2000 10h 19m, 1d 53'), with a statistical uncertainty of 11.3 degrees. The angle from the Fermi LAT boresight is 80.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217325/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217325/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217325/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39350. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37360] Fermi GRB 250216A: Global MASTER-Net observations report
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39349 SUBJECT: Fermi GRB 250216A: Global MASTER-Net observations report DATE: 25/02/16 23:02:13 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-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 250216A ( Fermi GBM team, GCN 39347) errorbox 7487 sec after notice time and 7522 sec after trigger time at 2025-02-16 22:26:06 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 32 deg. The sun altitude is -56.4 deg. The galactic latitude b = 54 deg., longitude l = 106 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2780267 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 7553 | 2025-02-16 22:26:06 | MASTER-Kislovodsk | (14h 04m 27.49s , +60d 18m 33.1s) | C | 60 | 17.3 | 7633 | 2025-02-16 22:27:26 | MASTER-Kislovodsk | (14h 20m 34.14s , +60d 16m 43.3s) | C | 60 | 17.5 | 7813 | 2025-02-16 22:30:27 | MASTER-Kislovodsk | (13h 47m 28.02s , +58d 25m 39.4s) | C | 60 | 17.1 | 7893 | 2025-02-16 22:31:47 | MASTER-Kislovodsk | (14h 02m 50.11s , +58d 24m 15.8s) | C | 60 | 17.0 | 8554 | 2025-02-16 22:42:48 | MASTER-Kislovodsk | (14h 04m 29.75s , +60d 18m 27.7s) | C | 60 | 15.7 | 8634 | 2025-02-16 22:44:07 | MASTER-Kislovodsk | (14h 20m 27.55s , +60d 17m 01.8s) | C | 60 | 16.6 | 8714 | 2025-02-16 22:45:27 | MASTER-Kislovodsk | (13h 47m 31.98s , +58d 24m 11.2s) | C | 60 | 15.6 | 8793 | 2025-02-16 22:46:47 | MASTER-Kislovodsk | (14h 02m 43.06s , +58d 25m 29.6s) | C | 60 | 16.3 | 8976 | 2025-02-16 22:49:50 | MASTER-Kislovodsk | (13h 51m 50.42s , +62d 12m 49.6s) | C | 60 | 16.0 | 9056 | 2025-02-16 22:51:10 | MASTER-Kislovodsk | (14h 08m 55.17s , +62d 13m 26.3s) | C | 60 | 16.0 | 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/39349. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37359] GRB 250215A / EP250215a: LCO detection of the afterglow
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39348 SUBJECT: GRB 250215A / EP250215a: LCO detection of the afterglow DATE: 25/02/16 21:11:38 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> I. Pérez-Fournon, F. Poidevin, D. Aguado, J.A. Acosta-Pulido, A. López-Oramas, D. Nespral (IAC and ULL), F. Acero (CEA Saclay and IAC), N.C. Sun (UCAS), W. Li, Y. Wang, Z. Niu (NAOC), D. Cano-Morales, I. Correa-Plasencia, and A.E. Hernández-Díaz (ULL) We observed the field of the Fermi long GRB 250215A (Fermi GBM Team, GCN Circ. 39327), detected also by Einstein Probe WXT and FXT (EP250215a, Wang et al., GCN Circ. 39329), INTEGRAL SPI-ACS (Barria et al., GCN Circ. 39331), AstroSat CZTI (Tembhurnikar et al., GCN Circ. 39334), SVOM/GRM (Zheng et al., GCN Circ. 39335), and Swift XRT (Page et al., GCN Circ. 39336) with the two Las Cumbres Observatory Global Telescope network (LCOGT) 1-m telescopes, equipped with Sinistro cameras, at the LCOGT node at the Siding Spring Observatory (Australia). We obtained two 600-sec exposures in the SDDS-i' filter starting at 2025-02-15 11:08:48 and 12:58:59 UT, respectively. The optical afterglow detected first by Liu et al. (GCN Circ. 39330) at a redshift of z = 4.61 (Sánchez-Ramírez et al., GCN Circ. 39343) is clearly detected in our LCOGT images with magnitudes of i' = 20.10 +/- 0.15 in the first observation (starting 8.615 after the trigger) and i' = 20.59 +/- 0.23 in the second one (starting 10.451 hr after trigger), with a clear fading between the two observations. The photometry has been calibrated against Pan-STARRS DR2 and is not corrected for Galactic extinction. These results are consistent with other optical detections of the afterglow (Liu et al., GCN Circ. 39330; Xie et al., GCN Circ. 39333; Malesani et al., GCN Circ. 39339; and Malesani et al. GCN Circ. 39341). This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2025A-009, SGLF). View this GCN Circular online at https://gcn.nasa.gov/circulars/39348. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37358] GRB 250216A: Fermi GBM Final Real-time Localization
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39347 SUBJECT: GRB 250216A: Fermi GBM Final Real-time Localization DATE: 25/02/16 20:31:20 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 20:20:43 UT on 16 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250216A (trigger 761430048.867762 / 250216848). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 212.4, Dec = 60.2 (J2000 degrees, equivalent to J2000 14h 09m, 60d 12'), with a statistical uncertainty of 12.7 degrees. The angle from the Fermi LAT boresight is 50.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250216848/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250216848/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250216848/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39347. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37357] EP250212a: FTW optical and NIR upper limits
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39346 SUBJECT: EP250212a: FTW optical and NIR upper limits DATE: 25/02/16 19:03:45 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann (LMU), Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU) and Antonella Palmese (Carnegie Mellon U.) report: We observed the EP-FXT localization area of EP250212a (Li et al., GCN 39308) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i and J band simultaneously for 18 x 180 s starting at 2025-02-15T23:51:26 UT (3.67 days after the WXT trigger). Earlier observations were not possible due to bad weather. Consistent with Malesani et al. (GCN 39306), Eyles-Ferris et al. (GCN 39309) and Junjie-Jin et al. (GCN 39319) we detect no source at a 3 sigma depth of r > 23.3 mag i > 23.0 mag J > 22.0 mag. The r- and i-band magnitudes are calibrated against the PS1 catalog and the J-band is calibrated with the 2MASS Catalog. All magnitudes are provided in the AB system and are not corrected for Galactic extinction. We thank Christoph Ries from the staff of the Wendelstein Observatory for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39346. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37356] GRB 250215A: Swift/UVOT Upper Limits
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39345 SUBJECT: GRB 250215A: Swift/UVOT Upper Limits DATE: 25/02/16 15:30:21 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M.H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250215A detected by Fermi, the Einstein Probe and INTEGRAL (GCN Circ. 39327; Wang et al., GCN Circ. 39329; Barria et al., GCN Circ. 39331) 19.5 ks after the trigger. The afterglow reported in the XRT (Page et al., GCN Circ. 39336) and optical/IR (Liu et al., GCN Circ. 39330; Xie et al., GCN Cic. 39333; Malesani et al., GCN Circ. 39339) is not detected in the single U-band exposure. This is consistent with the redshift of z=4.61 reported by Sanchez-Ramirez et al. (GCN Circ. 39343). Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposure is: Filter T_start(s) T_stop(s) Exp(s) Mag u 9504 16104 1704 >21.06 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.056 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/39345. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37355] GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39344 SUBJECT: GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow DATE: 25/02/16 14:01:44 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Jean-Grégoire Ducoin (CPPM), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Noémie Globus (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), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Benjamin Schneider (LAM) report: We imaged the field of GRB 250215A (Fermi GBM Team, GCN Circ. 39327, Barria et al., GCN Circ. 39331, Zheng et al., GCN Circ. 39335), originally detected as EP250215a (Wang et al., GCN Circ. 29329), with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-02-16 05:37 UTC to 10:18 UTC (1.13 to 1.32 days after the trigger) and obtained 200 minutes of exposure in the r filter at high airmass. The data were coadded with the COLIBRÍ pipeline and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our photometry is not corrected for Galactic extinction. At the position of the OT reported by Liu et al. (GCN Circ. 39330), we do not detect a point source to an estimated 3-sigma upper limit of r > 22.7 Our non-detection is in contrast to the slightly earlier detection at i ≈ 21.3 reported by Malesani et al. (GCN Circ. 39341). In retrospect, this is not unexpected, given the bandpass of our filter from 553-695 nm and the presence of Ly-alpha absorption below 682 nm due to the source redshift of 4.61 (Ramírez-Sánchez et al., GCN Circ. 39343). Our limiting magnitude is consistent with the limit in r reported by Liu et al. (GCN Circ. 39327), assuming a temporal decay index of approximately 0.9, estimated from the Gemini and NOT detections in i reported by Malesani et al. (GCN Circ. 39339 and 39341). 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/39344. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37354] EP250215a / GRB 250215A : GTC redshift z = 4.61
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39343 SUBJECT: EP250215a / GRB 250215A : GTC redshift z = 4.61 DATE: 25/02/16 11:58:30 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es> R. Sanchez-Ramirez, A. J. Castro-Tirado, M. D. Caballero-Garcia, S. Guziy, G. Garcia-Segura, I. Perez-Garcia and S.-Y. Wu (IAA-CSIC), M. Gritsevich (Univ. of Helsinki), D. Xu (NOAC), A. Martin-Carrillo (UCD), Y.-D. Hu (GXU), S.B. Pandey (UPSO), S. Geier and A. Cabrera-Lavers (GTC), on behalf of a larger collaboration, report: Following the detection of EP250215a/GRB250215A by EP/WXT (Wang et al. GCNC 39329), INTEGRAL/SPI-ACS (Barria et al. GCNC 39331), AstroSat CZTI (Tembhurnikar et al. GCNC 39334) SVOM/GRM (Zheng et al., GCN 39335) and Fermi/GBM (Scotton and Meegan, GCNC 39342), we triggered the 10.4m GTC in Observatorio del Roque de Los Muchachos (La Palma, Spain) in order to get an spectrum of the proposed optical afterglow detected by NOT (Liu et al., GCNC 39330, Malesani et al., GCNC 39341), SVOM/VT (Xie et al., GCN 39333) and Gemini-South (Malesani et al., GCNC 39339). Data was gathered starting on Feb 16, 2:27 UT (i.e. 23.9 hr post- burst), consisting of 4x1000s spectra with the R1000R grism, covering the range 5,200-10,000. Based on a preliminary reduction, we detect a prominent Ly-alpha absoption at ~6820A, plus several metal features interpreted as being due to SiII, CII, SiIV and CIV at a redshift of z = 4.61, wich we proposed to be the redshift of EP250215a/GRB250215A. View this GCN Circular online at https://gcn.nasa.gov/circulars/39343. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37353] GRB 250215A: Fermi GBM Observation
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39342 SUBJECT: GRB 250215A: Fermi GBM Observation DATE: 25/02/16 07:17:46 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> L. Scotton (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 02:31:54.94 UT on 15 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250215A (trigger 761279519/250215105), which was also detected by EP-WXT and FXT (Wang et al., GCN 39329), INTEGRAL SPI-ACS (Barria et al., GCN 39331), AstroSat CZTI (Tembhurnikar et al., GCN 39334), SVOM/GRM (Zheng et al., GCN 39335) and Swift-XRT (Page et al., GCN 39336). NOT (Liu et al., GCN 39330, Malesani et al., GCN 39341), SVOM/VT (Xie et al., GCN 39333) and Gemini-South (Malesani et al., GCN 39339) detected the optical counterpart. The Fermi GBM on-ground location is consistent with the Swift-XRT position. The angle from the Fermi LAT boresight is 28 degrees. The GBM light curve consists of multiple emission episodes with a duration (T90) of about 13.4 s (50-300 keV). The time-averaged spectrum from T0-0.8 to T0+14.5 s is best fit by a Band function with Epeak = 117 +/- 9 keV, alpha = -0.68 +/- 0.09 and beta = -2.38 +/- 0.14. The event fluence (10-1000 keV) in this time interval is (6.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+12 s in the 10-1000 keV band is 11.1 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/39342. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37352] EP250215a / GRB 250215A : NOT optical observations
by GCN Circulars 16 Feb '25

16 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39341 SUBJECT: EP250215a / GRB 250215A : NOT optical observations DATE: 25/02/16 03:06:15 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> D. B. Malesani (DAWN/NBI and Radboud Univ), D. Xu (NAOC), N. Pyykkinen (NOT and Turku Univ.), M. A. Diaz Teodori (NOT and Turku Univ.) report on behalf of a larger collaboration: We observed the optical counterpart (Liu et al., GCN 39330; Xie et al., GCN 39333; Malesani et al., GCN 39339) of EP250215a / GRB 250215A (Wang et al., GCN 39329; Fermi GBM Team, GCN 39327; Barria et al., GCN 39331; Tembhurnikar et al., GCN 39334; Zheng et al., GCN 39335) using the ALFOSC instrument installed on the Nordic Optical Telescope (NOT). Observations were carried out in the i band and consisted of 5x300 s exposures, with a mean epoch 2025 Feb 16.076 UT (23.29 hr after the trigger). The afterglow is well detected with a magnitude i = 21.34 +- 0.07 AB, calibrated against several stars from the Pan-STARRS catalog. View this GCN Circular online at https://gcn.nasa.gov/circulars/39341. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37351] GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39340 SUBJECT: GRB 250215A/EP250215a: 1.6m Mephisto optical observation report DATE: 25/02/15 18:49:42 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Xiangkun Liu, Yu Pan, Edoardo P. Lagioia, Yaosong Yu, Guowang Du, Brajesh Kumar, Yuan Fang, Jinghua Zhang, Xinlei Chen, Xingzhu Zou, Yuanpei Yang (all SWIFAR, YNU), Xuhui Han, Pinpin Zhang, Liping Xin, Chao Wu, Jianyan Wei (all NAOC), Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team: The field of GRB 250215A/EP250215a detected by Fermi Gamma-ray Burst Monitor (GBM) and EP-WXT (Fermi GBM Team, GCN 39327; Wang et al., GCN 39329) was observed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. Simultaneous uvgr band photometric observations were conducted starting from 16:33:12 2025-02-15 UT (~14 hr after the trigger) and 3 frames with 300s exposure times were taken. There is non-detection of the optical candidate (Liu et al., GCN 39330; Xie et al., GCN 39333; Malesani et al., GCN 39339) in the stacked images of uvgr bands. The preliminary photometry and 3 sigma upper limits are listed below. Start_Time(UT) | Band | Exp(s)| LimMag (AB) --------------------|--------|-------|------------ 2025-02-15T16:33:12 | u | 300*3 | >20.65 2025-02-15T16:50:23 | v | 300*3 | >20.91 2025-02-15T16:33:12 | g | 300*3 | >21.21 2025-02-15T16:50:23 | r | 300*3 | >21.45 ------------------------------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21. ------------------------------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/39340. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37350] GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39339 SUBJECT: GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening DATE: 25/02/15 17:52:20 GMT FROM: mariaedvige.ravasio(a)ru.nl Daniele B. Malesani (DAWN/NBI and Radboud Univ.), Jonathan Quirola-Vasquez (Radboud Univ.), Antonio Martin-Carrillo (UCD), Andrew J. Levan (Radboud Univ. and Warwick Univ.), Maria E. Ravasio (Radboud and INAF), Peter G. Jonker (Radboud Univ.) report on behalf of a larger collaboration: We observed the optical counterpart (Liu et al., GCN 39330; Xie et al., GCN 39333) of EP250215a / GRB 250215A (Fermi GBM Team, GCN 39327; Wang et al., GCN 39329; Barria et al., GCN 39331; Tembhurnikar et al., GCN 39334; Zheng et al., GCN 39335) using the GMOS instrument installed on the Gemini-South telescope. While no spectroscopy could be unfortunately performed due to a technical fault with the instrument, in a single 60-s i-band image, taken starting on 2025 Feb 15 at 08:48:23 UT (6.27 hr after the EP/WXT trigger), the afterglow is well detected with a magnitude i = 20.05 +- 0.07 AB (calibrated against nearby stars from the Pan-STARRS catalog). We note that our (i-band) magnitude is brighter than the z-band measurement reported at an earlier epoch by Liu et al. (GCN 39330). The VT_R magnitude (Xie et al., GCN 39333), taken at an intermediate epoch, is brighter than both other reports. This is likely to indicate a rebrightening. View this GCN Circular online at https://gcn.nasa.gov/circulars/39339. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37349] LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39338 SUBJECT: LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo DATE: 25/02/15 17:47:56 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, N.Tiurina, D.Vlasenko, P.Balanutsa, I.Panchenko, A.Chasovnikov K.Zhirkov, G.Antipov, A.Sankovich, I.Gorbunov, A.Sosnovskij, Yu.Tselik, Ya.Kechin, V.Senik, V.Topolev (Lomonosov MSU), O.Gress, N.Budnev, 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) Global MASTER robotic net (Lipunov, Kornilov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591, pp.http://www.pereplet.ru/lipunov/625.html#625) continued to observe OT AT2025bbo (Smart et al., GCN 39244) in GW LVK error area S250206dm (The LIGO-Virgo-Kagra Collaboration, GCN 39175): Date UT Exp Filter Site m err 250208 15:31:43 95 Clear MASTER600-Tunka >19.3 250209 16:54:16 1440 ~Rc MASTER-Kislovodsk 19.10 0.15 250209 18:25:58 3960 ~Rc MASTER-Kislovodsk 19.48 0.05 250210 16:30:06 2880 ~Rc MASTER-Kislovodsk 19.86 0.06 250212 16:02:30 3960 ~Rc MASTER-Kislovodsk >20.1 We did not see any variability in ATboo galaxy on arhive images. The galaxy arhive light curve from 2010 year is available at http://www.pereplet.ru/lipunov/images/ATbbo_galaxy_arhive_midi.jpg View this GCN Circular online at https://gcn.nasa.gov/circulars/39338. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37348] LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39338 SUBJECT: LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo DATE: 25/02/15 17:47:56 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, N.Tiurina, D.Vlasenko, P.Balanutsa, I.Panchenko, A.Chasovnikov K.Zhirkov, G.Antipov, A.Sankovich, I.Gorbunov, A.Sosnovskij, Yu.Tselik, Ya.Kechin, V.Senik, V.Topolev (Lomonosov MSU), O.Gress, N.Budnev, 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) Global MASTER robotic net (Lipunov, Kornilov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591, pp.http://www.pereplet.ru/lipunov/625.html#625) continued to observe OT AT2025bbo (Smart et al., GCN 39244) in GW LVK error area S250206dm (The LIGO-Virgo-Kagra Collaboration, GCN 39175): Date UT Exp Filter Site m err 250208 15:31:43 95 Clear MASTER600-Tunka >19.3 250209 16:54:16 1440 ~Rc MASTER-Kislovodsk 19.10 0.15 250209 18:25:58 3960 ~Rc MASTER-Kislovodsk 19.48 0.05 250210 16:30:06 2880 ~Rc MASTER-Kislovodsk 19.86 0.06 250212 16:02:30 3960 ~Rc MASTER-Kislovodsk >20.1 We did not see any variability in ATboo galaxy on arhive images. The galaxy arhive light curve from 2010 year is available at http://www.pereplet.ru/lipunov/images/ATbbo_galaxy_arhive_midi.jpg View this GCN Circular online at https://gcn.nasa.gov/circulars/39338. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37347] GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39337 SUBJECT: GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow DATE: 25/02/15 15:02:48 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Jean-Grégoire Ducoin (CPPM), Alan M. Watson (UNAM), Rosa L. Becerra (U Roma), Jean-Luc Atteia (IRAP), Benjamin Schneider (LAM) Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), and Ny Avo Rakotondrainibe (LAM) report: We imaged the field of the SVOM/ECLAIRs GRB 250213A (Wang et al., GCN Circ. 39317) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-02-15 02:22 UTC to 09:19 UTC (T+1.11 to T+1.40 days after the trigger) and obtained 229 minutes of exposure in the r filter under very poor seeing conditions. The data were coadded with the COLIBRÍ pipeline and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our field includes the position of the SVOM/VT optical afterglow candidate (Xin et al., GCN Circ. 39325) and the X-ray sources #2 (consistent with the VT source) and #3 (consistent with the SVOM/ECLAIRs uncertainty) in the Swift/XRT ToO observations (Evans et al., GCN Circ. 39321). At the position of the SVOM/VT optical candidate, after image subtraction, we do not detect a point source to a 3-sigma limit of: r > 22.8 Within the uncertainty region of XRT source #3, we do not detect any point sources to a 3-sigma limit of: r > 22.5 Our magnitude limits are not corrected for the substantial Galactic extinction in the direction of this burst, estimated to be A_V = 2.46 or A_r = 2.05 (Schlafly & Finkbeiner, 2011). 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/39337. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37346] GRB 250215A: Swift-XRT refined Analysis
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39336 SUBJECT: GRB 250215A: Swift-XRT refined Analysis DATE: 25/02/15 11:39:14 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 1.7 ks of XRT data for the Einstein Probe/WXT-detected burst GRB 250215A, from 9.5 ks to 16.1 ks after the Einstein Probe/WXT trigger, also detected by Fermi/GBM (GCN Circ. 39327) and INTEGRAL (GCN Circ. 39331). The data are entirely in Photon Counting (PC) mode. We detect a bright, previously uncatalogued X-ray source at the following coordinates: RA/Dec(J2000) = 156.33119, -27.69834, which is equivalent to RA (J2000): 10 25 19.48 Dec(J2000): -27 41 54.0 with an uncertainty of 3.6 arcsec (radius, 90% confidence). This source is 6 arcsec from the FXT position (GCN Circ. 39329) and 0.35 arcsec from the NOT optical counterpart (GCN Circ. 39330). The light curve can be modelled with a power-law decay with a decay index of alpha=1.1 (+/-0.4). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.95 (+0.23, -0.22). The best-fitting absorption column is 1.2 (+0.7, -0.5) x 10^21 cm^-2, consistent with the Galactic value of 6.8 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.2 (+0.7, -0.5) x 10^21 cm^-2 Galactic foreground: 6.8 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.95 (+0.23, -0.22) If the light curve continues to decay with a power-law decay index of 1.1, the count rate at T+24 hours will be 0.038 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x 10^-12 (1.7 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00019554. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39336. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37345] GRB 250215A: SVOM/GRM observation
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39335 SUBJECT: GRB 250215A: SVOM/GRM observation DATE: 25/02/15 11:26:40 GMT FROM: zhengchao_astro(a)foxmail.com SVOM/GRM team: Chao Zheng, Chen-wei Wang, Shi-Jie Zheng, Shao-Lin Xiong, Yue Huang, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Frédéric Piron (LUPM), Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia (IRAP) report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a long burst GRB 250215A (sb25021501) at 2025-02-15T02:32:03.300 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #39327), AstroSat (M. Tembhurnikar et al., GCN #39334) and INTEGRAL (Patrizia Barria et al., GCN 39331). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-pulses with a T90 of about 29.8 +7.8/-8.0 seconds in the 15-5000 keV band. The time-averaged spectrum from T0-25 to T0+25 s could be fit by a power law with high energy exponential cutoff function. The power law index is -1.39 +/- 0.15 and the cutoff energy, parameterized as Epeak, is 134 +/- 36 keV. The event fluence (10-1000 keV) in this time interval is (6.02 +/- 0.47)E-06 erg/cm^2. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250215A.png In addition, the position of this burst, as determined by EP/WXT (Wang et al., GCN #39329), is located at about 72 degrees from the SVOM optical axis, and outside the ECLAIRs field of view. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Chao Zheng (IHEP) (zhengchao97(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/39335. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37344] EP250215a / GRB 250215A: AstroSat CZTI detection
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39334 SUBJECT: EP250215a / GRB 250215A: AstroSat CZTI detection DATE: 25/02/15 09:57:33 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> M. Tembhurnikar (IUCAA), G. Waratkar (IITB), J. Joshi (IUCAA), 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 250215A which was also detected by Fermi/GBM (Fermi-GBM Team, GCN Circ. 39294), INTEGRAL/SPI-ACS (Barria et al., GCN Circ. 39331), and is associated with EP250215a (Wang et al., GCN Circ. 39329). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-02-15 02:32:07.5 UTC. The measured peak count rate associated with the burst is 131 (+31, -33) counts/s above the background in the combined data of three quadrants (out of four), with a total of 585 (+253, -261) counts. The local mean background count rate was 247 (+4, -4) counts/s. Using cumulative rates, we measure a T90 of 15 (+9, -7) 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 2025-02-15 02:32:07.4 UTC. The measured peak count rate associated with the burst is 388 (+59, -65) counts/s above the background in the combined data of all quadrants, with a total of 1974 (+583, -715) counts. The local mean background count rate was 2231 (+8, -8) counts/s. We measure a T90 of 13 (+9, -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/39334. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37343] GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39333 SUBJECT: GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation DATE: 25/02/15 09:53:01 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> W.J. Xie (NAOC), Y.H. Cheng (SWIFAR, YNU), B.-T.Wang (YNAO, CAS), L.P. Xin, Y.L. Qiu, H.L. Li, C. Wu, Z.H. Yao, Y.N. Ma, X.H. Han, H.B. Cai, J. Wang, J.Y. Wei (NAOC), report on behalf of the SVOM team: The SVOM/VT conducted a ToO follow-up observations of the GRB 250215A / EP250215a (Fermi GBM Team, GCN 39327, Wang et al., GCN 39329) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. With the X band downlinked data, an uncatalogued optical source was clearly detected within the errorbox of EP/FXT (Wang et al., GCN 39329) in VT_R and VT_B single images, compared to the PanSTARRS and DESI catalogues. The position of source is consistent with the candidate reported (Liu et al., GCN 39300). The brightness of the source was estimated to be 19.3+/-0.1 mag in AB magnitude in VT_R, 22.2+/-0.2 mag in AB magnitude in VT_B, at the mid time of 1.07 hours post the burst, with an exposure time of 100 seconds for each frame. Considering the red color of the source based on the VT data, it is likely a high redshift or highly extincted burst. More deep follow-ups are encouraged. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/39333. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37342] EP250215a: Global MASTER-Net observations report
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39332 SUBJECT: EP250215a: Global MASTER-Net observations report DATE: 25/02/15 09:27:45 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 EP250215a ( EP Team et al., GCN 39329) errorbox 12952 sec after notice time and 19891 sec after trigger time at 2025-02-15 08:03:34 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 36 deg. The sun altitude is -26.0 deg. The galactic latitude b = 25 deg., longitude l = 268 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2779105 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 19952 | 2025-02-15 08:03:34 | MASTER-OAFA | (10h 25m 20.58s , -27d 18m 50.7s) | C | 120 | 19.2 | 20089 | 2025-02-15 08:05:51 | MASTER-OAFA | (10h 25m 27.87s , -27d 19m 50.1s) | C | 120 | 19.1 | 20229 | 2025-02-15 08:08:11 | MASTER-OAFA | (10h 25m 22.22s , -27d 20m 50.0s) | C | 120 | 19.2 | 20366 | 2025-02-15 08:10:29 | MASTER-OAFA | (10h 25m 26.63s , -27d 20m 46.2s) | C | 120 | 19.1 | 20501 | 2025-02-15 08:12:43 | MASTER-OAFA | (10h 25m 24.54s , -27d 18m 50.9s) | C | 120 | 19.1 | 20635 | 2025-02-15 08:14:57 | MASTER-OAFA | (10h 25m 24.64s , -27d 20m 24.4s) | C | 120 | 19.1 | 20756 | 2025-02-15 08:17:14 | MASTER-OAFA | (10h 25m 26.91s , -27d 19m 17.0s) | C | 90 | 18.8 | 20861 | 2025-02-15 08:18:58 | MASTER-OAFA | (10h 25m 20.89s , -27d 19m 50.8s) | C | 90 | 18.8 | 20982 | 2025-02-15 08:20:44 | MASTER-OAFA | (10h 25m 22.37s , -27d 18m 51.4s) | C | 120 | 19.1 | 21119 | 2025-02-15 08:23:01 | MASTER-OAFA | (10h 25m 28.21s , -27d 19m 51.3s) | C | 120 | 19.1 | 21256 | 2025-02-15 08:25:19 | MASTER-OAFA | (10h 25m 21.51s , -27d 20m 51.9s) | C | 120 | 19.0 | 21391 | 2025-02-15 08:27:34 | MASTER-OAFA | (10h 25m 27.37s , -27d 20m 41.7s) | C | 120 | 19.0 | 21526 | 2025-02-15 08:29:48 | MASTER-OAFA | (10h 25m 25.28s , -27d 18m 52.8s) | C | 120 | 19.0 | 21660 | 2025-02-15 08:32:03 | MASTER-OAFA | (10h 25m 25.40s , -27d 20m 40.2s) | C | 120 | 19.0 | 21795 | 2025-02-15 08:34:17 | MASTER-OAFA | (10h 25m 28.35s , -27d 19m 02.2s) | C | 120 | 19.0 | 21932 | 2025-02-15 08:36:35 | MASTER-OAFA | (10h 25m 21.96s , -27d 19m 54.5s) | C | 120 | 19.0 | 22067 | 2025-02-15 08:38:49 | MASTER-OAFA | (10h 25m 22.37s , -27d 18m 55.5s) | C | 120 | 18.9 | 22204 | 2025-02-15 08:41:06 | MASTER-OAFA | (10h 25m 28.60s , -27d 19m 56.0s) | C | 120 | 19.0 | 22337 | 2025-02-15 08:43:20 | MASTER-OAFA | (10h 25m 21.80s , -27d 20m 57.2s) | C | 120 | 18.8 | 22474 | 2025-02-15 08:45:37 | MASTER-OAFA | (10h 25m 28.74s , -27d 20m 57.8s) | C | 120 | 18.9 | 22609 | 2025-02-15 08:47:52 | MASTER-OAFA | (10h 25m 25.92s , -27d 19m 19.8s) | C | 120 | 18.9 | 22748 | 2025-02-15 08:50:11 | MASTER-OAFA | (10h 25m 26.03s , -27d 20m 48.4s) | C | 120 | 18.8 | 22886 | 2025-02-15 08:52:28 | MASTER-OAFA | (10h 25m 28.99s , -27d 19m 28.0s) | C | 120 | 18.7 | 23213 | 2025-02-15 08:57:55 | MASTER-OAFA | (10h 25m 24.10s , -27d 19m 02.5s) | C | 120 | 18.7 | 23486 | 2025-02-15 09:02:28 | MASTER-OAFA | (10h 25m 23.94s , -27d 21m 04.4s) | C | 120 | 18.7 | 23619 | 2025-02-15 09:04:42 | MASTER-OAFA | (10h 25m 29.40s , -27d 21m 00.5s) | C | 120 | 18.7 | 23754 | 2025-02-15 09:06:57 | MASTER-OAFA | (10h 25m 26.53s , -27d 19m 19.4s) | C | 120 | 18.6 | 23889 | 2025-02-15 09:09:12 | MASTER-OAFA | (10h 25m 26.64s , -27d 20m 45.9s) | C | 120 | 18.6 | 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/39332. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37341] EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39331 SUBJECT: EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection DATE: 25/02/15 07:50:45 GMT FROM: Aishwarya L Thakur at INAF-IAPS, Rome <aishth(a)outlook.com> Patrizia Barria(a,b), Giulia Gianfagna(a), James Craig Rodi(a), Aishwarya Linesh Thakur(a), Luigi Piro(a), Lorenzo Natalucci(a,b) report: GRB 250215A was discovered by Fermi/GBM (GCN 39327) at 2025-02-15T02:31:54 (UTC) and Einstein Probe/WXT (GCN 39329) at 2025-02-15T02:32:03 (UTC). In an SPI-ACS light curve above 80 keV, we find a signal temporally coincident with the GBM detection, having an approximate duration of ~ 18 sec. The signal consists of three pulses over this duration. Our detection confirms that GRB 250215A and EP250215A are the same event. The approximate peak count rate in SPI-ACS for E>80 keV is 68,000 cts/s, over a median background rate of 64,458 cts/s. This work is based on observations with INTEGRAL, an ESA project with instruments and a science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, and Spain), and with the participation of Russia and the USA. The SPI-ACS detector system has been provided by MPE Garching/Germany. ----- (a) INAF/IAPS-Rome (b) ICSC National Research Centre for High-Performance Computing View this GCN Circular online at https://gcn.nasa.gov/circulars/39331. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37340] EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39330 SUBJECT: EP250215a / GRB 250215A (potentially): NOT likely optical counterpart DATE: 25/02/15 04:44:25 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> X. Liu, Z.P. Zhu, J. An, S.Y. Fu, S.Q. Jiang, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), N. Pyykkinen, M. A. Diaz Teodori (NOT) report on behalf of a large collaboration: We observed the field of EP250215a (Wang et al., GCN 39329), using the ALFOSC instrument mounted on the Nordic Optical Telescope (NOT). EP250215a is basically consistent with GRB 250215A also newly detected by Fermi/GBM (Fermi GBM team, GCN 39327) in both trigger time and position. Therefore, they seem to be an identical event. We obtained 5 x 180 s frames in the SDSS-z band at a median time of 0.45 hr after the EP trigger. An uncatalogued optical transient (OT) is detected in the stacked image within the EP/FXT error circle (Wang et al., GCN 39329) at coordinates R.A. (J2000) = 10:25:19.49 Dec. (J2000) = -27:41:54.37 with an uncertainty of ~ 0.5 arcsec. The OT has z ~ 20.6 mag, calibrated with Pan-STARRS DR1 and not corrected for Galactic extinction. There was no known NEO object at the above position by checking MPC. The 3-sigma limiting magnitude of the image is z ~ 21.5 (AB). We thus conclude the OT is very likely the optical counterpart of EP250215a. Further observations are planned. View this GCN Circular online at https://gcn.nasa.gov/circulars/39330. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37339] EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39329 SUBJECT: EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient DATE: 25/02/15 04:26:05 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> C. Y. Wang(THU), A. Li (BNU), D. H. Zhao, Z. X. Ling (NAOC, 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 EP250215a (trigger ID: 01709131576). The WXT position of the source is R.A. = 156.3430 deg, DEC = -27.7040 deg (J2000) with an uncertainty of 2.9 arcmin in radius (90% C.L. statistical and systematic). The transient triggered EP-WXT at 2025-02-15T02:32:03 (UTC). The trigger time and the position are generally consistent with the likely long GRB 250215A (GCN #39327). 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. = 156.3301 deg, DEC = -27.6997 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/39329. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37338] Fermi GRB 250215A: Global MASTER-Net observations report
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39328 SUBJECT: Fermi GRB 250215A: Global MASTER-Net observations report DATE: 25/02/15 03:17:00 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 250215A ( Fermi GBM team, GCN 39327) errorbox 553 sec after notice time and 587 sec after trigger time at 2025-02-15 02:41:42 UT, with upper limit up to 18.7 mag. The observations began at zenith distance = 40 deg. The sun altitude is -19.3 deg. The galactic latitude b = 20 deg., longitude l = 273 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2779054 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 617 | 2025-02-15 02:41:42 | MASTER-SAAO | (10h 29m 47.15s , -34d 28m 22.2s) | C | 60 | 18.3 | 677 | 2025-02-15 02:41:42 | MASTER-SAAO | (10h 29m 47.15s , -34d 28m 22.1s) | C | 180 | 18.7 | Coadd 697 | 2025-02-15 02:43:01 | MASTER-SAAO | (10h 29m 47.06s , -34d 28m 20.0s) | C | 60 | 18.2 | 776 | 2025-02-15 02:44:20 | MASTER-SAAO | (10h 29m 46.95s , -34d 28m 17.6s) | C | 60 | 18.2 | 855 | 2025-02-15 02:45:39 | MASTER-SAAO | (10h 29m 46.86s , -34d 28m 15.1s) | C | 60 | 18.1 | 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/39328. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37337] GRB 250215A: Fermi GBM Final Real-time Localization
by GCN Circulars 15 Feb '25

15 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39327 SUBJECT: GRB 250215A: Fermi GBM Final Real-time Localization DATE: 25/02/15 02:42:29 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 02:31:54 UT on 15 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250215A (trigger 761279519.94116 / 250215105). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 157.6, Dec = -34.5 (J2000 degrees, equivalent to J2000 10h 30m, -34d 30'), with a statistical uncertainty of 2.7 degrees. The angle from the Fermi LAT boresight is 21.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250215105/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250215105/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250215105/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39327. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37336] Fermi trigger No 761206993: Global MASTER-Net observations report
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39326 SUBJECT: Fermi trigger No 761206993: Global MASTER-Net observations report DATE: 25/02/14 20:15:48 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 GRB250214.27 (trigger No 761206993,23h 50m 45.60s , -06d 14m 24.0s, R=4.1) errorbox 43582 sec after notice time and 43595 sec after trigger time at 2025-02-14 18:29:44 UT, with upper limit up to 17.2 mag. Observations started at twilight. The observations began at zenith distance = 78 deg. The sun altitude is -12.8 deg. The galactic latitude b = -65 deg., longitude l = 87 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2777879 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 43625 | 2025-02-14 18:29:44 | MASTER-SAAO | (00h 03m 58.24s , -08d 29m 08.1s) | C | 60 | 16.3 | 43838 | 2025-02-14 18:33:16 | MASTER-SAAO | (00h 00m 16.36s , -10d 20m 51.8s) | C | 60 | 16.7 | 44048 | 2025-02-14 18:36:46 | MASTER-SAAO | (00h 04m 04.34s , -10d 21m 00.8s) | C | 60 | 17.0 | 44127 | 2025-02-14 18:38:05 | MASTER-SAAO | (00h 11m 16.32s , -06d 33m 56.5s) | C | 60 | 17.0 | 44501 | 2025-02-14 18:44:20 | MASTER-SAAO | (00h 11m 09.97s , -04d 40m 18.3s) | C | 60 | 16.8 | 44583 | 2025-02-14 18:45:41 | MASTER-SAAO | (00h 11m 15.93s , -08d 27m 11.1s) | C | 60 | 17.2 | 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/39326. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37335] GRB 250213A：SVOM/VT optical candidate
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39325 SUBJECT: GRB 250213A：SVOM/VT optical candidate DATE: 25/02/14 15:17:24 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> L.P. Xin, Y.L. Qiu, H.L. Li(NAOC), Y. Wang(PMO), W.J. Xie, C. Wu, Z.H. Yao, Y.N. Ma, X.H. Han, H.B. Cai, J. Wang, J.Y. Wei (NAOC), report on behalf of the SVOM team: The SVOM/VT conducted follow-up observations of the GRB 250213A (Wang et al., GCN 39317) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. With the X band downlinked data, an uncatalogued optical source was detected within the errorbox of XRT2 (Evens et al., GCN 39321) in VT_R stacked image, compared to the Pan-STARRS DR1 catalog. The brightness of the source was estimated to be 22.5 +/-0.2 mag in AB magnitude in VT_R image at the mid time of 3.28 hours post the burst, with a total exposure time of 42*100 seconds. The source is located at RA, Dec =112.55872, =-19.94929, which is equivalent to: RA (J2000) : 07:30:14.1 Dec (J2000): -19:56:57.44 with an uncertainty of 0.5 arcsec. Based on the data available, we are not sure wether it is a persistent source or the candidate for the burst. More deep follow-ups are encouraged to confirm the nature of the source. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/39325. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37334] Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39324 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB DATE: 25/02/14 14:23:28 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> E. Bissaldi (Politecnico and INFN Bari) reports on behalf of the Fermi GBM Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 761206993/250214266 at 06:23:08.86 UT on 14 February 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/39324. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37333] Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39324 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB DATE: 25/02/14 14:23:28 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> E. Bissaldi (Politecnico and INFN Bari) reports on behalf of the Fermi GBM Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 761206993/250214266 at 06:23:08.86 UT on 14 February 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/39324. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37332] EP250207b: Xinglong optical upper limit
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39323 SUBJECT: EP250207b: Xinglong optical upper limit DATE: 25/02/14 10:19:21 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), Yue-Sun(NAOC), Zhou-Fan(NAOC), Hong-Wu(NAOC) report on behalf of a large collaboration: Following the detection of EP250207b by EP-WXT (Zhou et al., GCN 39266 ), we observed the field of EP250207b using Tsinghua-NAOC 0.8-m telescope (TNT) located at Xinglong, Hebei, China. A total of 3600 s N-band exposures were taken , with a median observation time of 2025-02-08T16:39:35, approximately 18.86 hours after the EP FXT trigger (2025-02-07T21:47:56). No optical counterpart was detected, with a 5-sigma limiting magnitude of 19.9, calibrated with Pan-STARRS sources in the field. View this GCN Circular online at https://gcn.nasa.gov/circulars/39323. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37331] Fermi GRB 250214A: Global MASTER-Net observations report
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39322 SUBJECT: Fermi GRB 250214A: Global MASTER-Net observations report DATE: 25/02/14 10:03:16 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 250214A ( Fermi GBM team, GCN 39320) errorbox 560 sec after notice time and 594 sec after trigger time at 2025-02-14 05:42:01 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 30 deg. The sun altitude is -44.1 deg. The galactic latitude b = -4 deg., longitude l = 259 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2777807 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 644 | 2025-02-14 05:42:01 | MASTER-OAFA | (08h 23m 56.50s , -41d 11m 58.0s) | C | 100 | 18.2 | 655 | 2025-02-14 05:42:01 | MASTER-OAFA | (08h 11m 47.16s , -41d 33m 12.7s) | C | 120 | 19.1 | 781 | 2025-02-14 05:44:07 | MASTER-OAFA | (08h 23m 56.66s , -41d 11m 56.7s) | C | 120 | 18.3 | 791 | 2025-02-14 05:44:08 | MASTER-OAFA | (08h 11m 47.35s , -41d 33m 11.9s) | C | 140 | 19.1 | 942 | 2025-02-14 05:46:34 | MASTER-OAFA | (08h 23m 56.87s , -41d 11m 55.7s) | C | 150 | 18.3 | 952 | 2025-02-14 05:46:34 | MASTER-OAFA | (08h 11m 47.60s , -41d 33m 11.2s) | C | 170 | 19.0 | 1123 | 2025-02-14 05:49:30 | MASTER-OAFA | (08h 23m 57.07s , -41d 11m 55.2s) | C | 160 | 18.4 | 1133 | 2025-02-14 05:49:30 | MASTER-OAFA | (08h 11m 47.85s , -41d 33m 10.2s) | C | 180 | 18.8 | 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/39322. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37330] GRB 250213A: Swift ToO observations
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39321 SUBJECT: GRB 250213A: Swift ToO observations DATE: 25/02/14 07:03:29 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the SVOM/ECLAIRs GRB 250213A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021777 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the SVOM/ECLAIRs event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39321. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37329] GRB 250214A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39320 SUBJECT: GRB 250214A: Fermi GBM Final Real-time Localization DATE: 25/02/14 05:42:39 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 05:32:07 UT on 14 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250214A (trigger 761203932.174936 / 250214231). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 122.8, Dec = -41.9 (J2000 degrees, equivalent to J2000 08h 11m, -41d 53'), with a statistical uncertainty of 5.3 degrees. The angle from the Fermi LAT boresight is 122.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250214231/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250214231/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250214231/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39320. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37328] EP250212a: Xinglong optical upper limit
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39319 SUBJECT: EP250212a: Xinglong optical upper limit DATE: 25/02/14 03:31:35 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Junjie-Jin(NAOC), Haiyang-Mu(NAOC), Yinan-Zhu(NAOC), Jiajun-Jia(NAOC), YuGuang-Sun(NAOC), Zhou-Fan(NAOC), Hong-Wu(NAOC) report on behalf of a large collaboration: Following the detection of EP250212a by EP-WXT (Li et al., GCN 39308), we observed the field of EP250212a using Tsinghua-NAOC 0.8-m telescope (TNT) located at Xinglong, Hebei, China. A total of 3600 s N-band exposures were taken , with a median observation time of 2025-02-12 14:27:29, approximately 6.72 hours after the EP trigger. No optical counterpart was detected, with a 5-sigma limiting magnitude of 20.7, calibrated with Pan-STARRS sources in the field. Later，We observed the EP250212a by the Xinglong 2.16-m telescope located at Xinglong, Hebei, China. A total of 1200 s N-band exposures were taken , with a median observation time of 2025-02-12 16:15:05, approximately 8.52 hours after the EP trigger. No optical counterpart was detected, with a 5-sigma limiting magnitude of 21.7, calibrated with Pan-STARRS sources in the field. View this GCN Circular online at https://gcn.nasa.gov/circulars/39319. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37327] LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39318 SUBJECT: LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates DATE: 25/02/14 01:40:50 GMT FROM: Tomas Cabrera <tcabrera(a)andrew.cmu.edu> Tomás Cabrera (CMU), Lei Hu (CMU), Xander Hall (CMU), Antonella Palmese (CMU), Igor Andreoni (UNC), Keerthi Kunnumkai (CMU), Brendan O’Connor (CMU), on behalf of the GW-MMADS team We observed the southern high probability area of the LVK gravitational wave candidate S250206dm (GCN 39175) using the wide-field Dark Energy Camera (DECam) on the 4m Blanco telescope, as part of the Gravitational Wave Multi-Messenger Astronomy DECam Survey (GW-MMADS; PI: Andreoni & Palmese). Observations started at 2025-02-13 06:15 UTC and covered 9.7% of the total event probability in the Bilby.offline1 S250206dm skymap (GCN 39231), a majority of the probability observable from the Blanco Telescope. These observations were started at the earliest possible time following the GW alert, since DECam was not available on the telescope at the time of the alert. The median 5sigma depths of our exposures are r\~22.6 mag and i\~23.1 mag. Our pointings have been posted on TreasureMap at [https://treasuremap.space/alerts?graceids=S250206dm](https://treasuremap.sp…. We run the SFFT difference imaging (Hu et al. 2022) on the available images, filter out likely stars and moving objects, visually inspect the remaining transients, and remove transients showing SNR>5 detections predating the alert from ATLAS forced photometry. We reported on TNS new transients within the LVK 90% CI area, and we report here those matched to a NED galaxy in the catalog reported by GCN 39235: | id | AT name | ra | dec | discovery_date (UT) | mag_i | mag_i_err | mag_r-mag_i | | ------------------------ | ---------- | ---------- | ---------- | ----------------------- | ------ | ----- | ----- | | T202502131633495m700257* | AT 2025bnt | 248.456112 | -70.049160 | 2025-02-13 06:52:20.818 | 21.359 | 0.062 | 0.886 | | T202502131558164m675652* | AT 2025bob | 239.568537 | -67.947727 | 2025-02-13 06:26:32.375 | 21.656 | 0.084 | 1.360 | | T202502131622522m690124* | AT 2025bnm | 245.717365 | -69.023307 | 2025-02-13 06:46:37.789 | 22.104 | 0.165 | -0.496 | We also report other potentially interesting transients showing a red color: | id | AT name | ra | dec | discovery_date (UT) | mag_i | mag_i_err | mag_r-mag_i | | ----------------------- | ---------- | ---------- | ---------- | ----------------------- | ------ | ----- | ------ | | T202502131559510m665547 | AT 2025bnj | 239.962646 | -66.929715 | 2025-02-13 06:35:06.754 | 20.869 | 0.042 | >1.238 | | T202502131552222m700443 | AT 2025bnp | 238.092561 | -70.078637 | 2025-02-13 06:32:14.412 | 21.141 | 0.057 | 0.540 | | T202502131632382m683103 | AT 2025bnh | 248.159200 | -68.517481 | 2025-02-13 07:06:47.575 | 21.446 | 0.063 | 2.151 | | T202502131628244m704858 | AT 2025bms | 247.101545 | -70.816131 | 2025-02-13 06:55:13.894 | 21.375 | 0.062 | 1.003 | \* - *We note that these transients may have tentative low SNR pre-detections from ATLAS forced photometry.* Further analysis is underway. We thank the CTIO and NOIRLab staff for supporting these observations and the data calibration. View this GCN Circular online at https://gcn.nasa.gov/circulars/39318. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37326] GRB 250213A: SVOM detection of a burst
by GCN Circulars 14 Feb '25

14 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39317 SUBJECT: GRB 250213A: SVOM detection of a burst DATE: 25/02/14 00:57:43 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Yun Wang (MPO), Wen-Jin Xie (NAOC), J.-L. Atteia (IRAP), N. Dagoneau (CEA), F. Piron (LUPM), Li Zhang (IHEP) report on behalf of the SVOM mission team. At 2025-02-13T23:46:24 UTC (Tb) SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250213A (SVOM burst-id sb25021316). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 2 alerts. IMT provided the alert with the best signal-to-noise-ratio (SNR) of 7.50 in the [8-50] keV energy band over a time window of 20.48 seconds starting at Tb. The localization of the best alert is R.A., Dec 112.4888, -20.0967 degrees: RA (J2000) = 7h29m57.31s Dec (J2000) = -20d05m48.10s with a 90% C.L. radius of 10.46 arcmin (including systematic error of 2 arcmin added in quadrature). A SVOM follow-up ToO observation has been scheduled. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. The Burst Advocate (BA) on shift for this burst is Yun Wang (wangyun(a)pmo.ac.cn) Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/39317. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37325] EP250212a: Global MASTER-Net observations report
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39316 SUBJECT: EP250212a: Global MASTER-Net observations report DATE: 25/02/13 23:54:28 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-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) was pointed to the EP250212a ( EP Team et al., GCN 39308) errorbox 72840 sec after notice time and 1 days 57035 sec after trigger time at 2025-02-13 23:34:42 UT, with upper limit up to 15.6 mag. The observations began at zenith distance = 42 deg. The sun altitude is -49.1 deg. The galactic latitude b = 30 deg., longitude l = 157 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2776627 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 143466 | 2025-02-13 23:34:42 | MASTER-Kislovodsk | (07h 38m 18.21s , +60d 29m 46.9s) | C | 60 | 15.6 | 143651 | 2025-02-13 23:37:47 | MASTER-Kislovodsk | (07h 38m 19.93s , +60d 29m 53.1s) | C | 60 | 15.3 | 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/39316. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37324] GRB 250205A: VIRT Optical Upper Limit
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39315 SUBJECT: GRB 250205A: VIRT Optical Upper Limit DATE: 25/02/13 22:07:44 GMT FROM: Priya Gokuldass at ERAU <gokuldap(a)my.erau.edu> K. Smith (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), B. Gendre (UVI), D. Morris (NASA), T. Lombardi (Eckerd College), F. George (ERAU), D. Smith (UVI), and C. Watson (UVI) report: We observed the field of GRB250205A (Saccardi et al., GCN 39154) with the 0.5m Virgin Islands Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2025-02-06 starting at 1:04:43 (T-mid ~ T0 + 4.66 hrs). We performed a series of exposures in an R filter with a total exposure of 3560s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.06. We do not detect any source within the XRT position (Kennea et al. GCN 39161). This non-detection is consistent with reported detections (Palmerio et al., GCN 39159; Gompertz et al., GCN 39156; Schneider et al., GCN 39157; Busmann et al., GCN 39169; and de Ugarte Postigo et al., GCN 39160 ), detection of afterglow (Watson et al., GCN 39169) and upper limits (Gompertz et al., GCN 39158; Breeveld et al., GCN 39168; Ferro et al., GCN 39170; and Gupta et al., GCN 39240 ). We report the following 3-sigma upper limit: T_mid ||Exposure ||Filter ||Limit T+ 4.66 hrs || 3560 s || R || > 21.14 The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. We acknowledge financial support from NASA EPSCoR award 80NNSC22M0063, NSF PAARE award 2319415, and NASA EPSCoR award 80NSSC24M0112. This message can be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39315. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37323] GRB 250205A: Leavitt Observatory optical upper limit
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39314 SUBJECT: GRB 250205A: Leavitt Observatory optical upper limit DATE: 25/02/13 21:56:42 GMT FROM: leavittob(a)gmail.com E. Pavoni and L. Moretti (Leavitt Observatory, Manciano, Italy) Members of: GRB/UAI - Gamma Ray Burst Section of Unione Astrofili Italiani ATA - Associazione Tuscolana di Astronomia In a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), report: We observed the field of GRB 250205A (Saccardi et al. GCN 39154) with our RC telescope (D=250 mm, F/D=8) of Leavitt Observatory, Manciano, Italy. The observations started approximately 43 minutes after the SVOM/ECLAIRs trigger time, with good weather conditions, and consisted of 8 individual frames of 240sec each in the R (Cousins) band. Images were processed using the astropy package (Astropy Collaboration et al., 2022ApJ...935..167A). In the stacked frame, we did not found any optical uncatalogued object within the SVOM error circle. Mid Time (UTC) Limit (R filter) Err. 2025-02-05T22:28:28 >19.1 0.1 The non-detection of the burst is consistent with detection and upper limits already reported (Gompertz et al. GCN 39156; Schneider et al., GCN 39157; Gompertz et al., GCN 39158; Palmerio et al., GCN 39159; A. de Ugarte Postigo et al., GCN 39160; Watson et al., GCN 39162; Breeveld et al., GCN 39168; Busmann et al., GCN 39169; Ferro et al., GCN 39170; Gupta et al., GCN 39240; Calapai et al., GCN 39302). Magnitude was calibrated with the nearby Pan-STARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied. The message may be cited. Reference: https://leavittobservatory.altervista.org View this GCN Circular online at https://gcn.nasa.gov/circulars/39314. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37322] GRB 250210A: GRBAlpha detection
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39313 SUBJECT: GRB 250210A: GRBAlpha detection DATE: 25/02/13 21:51:35 GMT FROM: Lea Szakszonová <lea.szakszonova60(a)gmail.com> L. Szakszonova, M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, M. Kolar,J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration. The long-duration GRB 250210A (FERMI/GBM: GCN Circular 39262, AstroSat/CZTI: GCN Circular 39267, INTEGRAL/SPI-ACS: CGN Circular 39268, SVOM/GRM: CGN Circular 39282) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract). The detection was confirmed at the peak time 2025-02-10 05:32:02.5 UTC. The T90 duration measured by GRBAlpha is 22.5 s and the overall significance during T90 reaches 11.8 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB250210A_GCN.pdf All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. View this GCN Circular online at https://gcn.nasa.gov/circulars/39313. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37321] EP250207B: Chandra localization of the X-ray counterpart
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39312 SUBJECT: EP250207B: Chandra localization of the X-ray counterpart DATE: 25/02/13 20:29:54 GMT FROM: Eleonora Troja <nora.gsfc(a)gmail.com> E. Troja (U Rome) reports on behalf of the ERC BHianca team: We imaged the field of the fast X-ray transient EP250207B (Zhou et al. GCN 39266) with the Chandra X-ray Observatory. Observations started on 2025 Feb 12.8 UT (~4.9 days after the trigger), using the ACIS-S instrument, for a total exposure time of 24.5 ks. Within the FXT localization (Zhou et al. GCN 39266) a single X-ray source is detected with significance >99.99% (Kraft, Burrows & Nousek, 1990) at a position consistent with the NOT optical candidate (Liu et al. GCN 39300). The inferred X-ray flux is consistent with the rapid afterglow decay reported by the EP/FXT observations (Zhou et al. GCN 39266). This supports the association between the Chandra source and EP250207B and confirms that the candidate reported by Liu et al. (GCN 39300) is its optical counterpart. No X-ray source is visible at the position of any other optical candidate (Eyles-Ferris et al. GCN 39281, Fraser et al. GCN 39287). Although the Chandra localization implies a 10 arcsec offset from the center of the nearby galaxy WISEA J111002.65-075211.9, the probability of a chance alignment remains relatively small (<1%, Bloom et al. 2002). Further observations to establish the nature of EP250207B and its distance scale are encouraged. We thank the Chandra director, Pat Slane, for awarding discretionary time and the observatory staff for rapidly scheduling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39312. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37320] LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39311 SUBJECT: LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies DATE: 25/02/13 20:19:59 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann (LMU), Daniel Gruen (LMU), Antonella Palmese (Carnegie Mellon U.), Brendan O’Connor (Carnegie Mellon U.), Yajie Zhang (LMU), Julius Gassert (LMU), Lei Hu (Carnegie Mellon U.), Arno Riffeser (LMU/MPE), Julian Sommer (LMU), Lena Schnappinger (LMU), Franziska Krause (LMU) and Elia Engelhard (LMU) report: We observed transients discovered in the search for a counterpart of S250206dm (LIGO Scientific Collaboration et al., GCN 39175; LIGO Scientific Collaboration et al., GCN 39184) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J bands simultaneously. ### AT2025bbo We observed AT2025bbo (Smartt et al., GCN 39244; Liu et al., GCN 39249; Lee et al., GCN 39252; Ducoin et al., GCN 39258; Huber et al., GCN 39272; Karambelkar et al., GCN 39273; Chen et al., GCN 39285; Xu et al., GCN 39293) in riJ bands on 2025-02-09 and on 2025-02-10. Difference imaging of our data, between the two epochs (riJ) and against PS1 (ri) and UKIDSS (J) archival images, reveals no confident detection of a source. The depths of our observations are as follows: | Time (UT) | Band | Exposures | Depth (3 sigma, AB mag) | |---------------------|------|-----------|-------------------------| | 2025-02-09T21:26:34 | r | 10x 180s | 22.9 | | 2025-02-09T21:26:34 | i | 10x 180s | 22.7 | | 2025-02-09T21:26:48 | J | 10x 180s | 21.6 | | 2025-02-10T20:18:10 | r | 5x 180s | 22.3 | | 2025-02-10T20:18:10 | i | 5x 180s | 22.2 | | 2025-02-10T20:18:25 | J | 5x 180s | 21.2 | ### AT2025bcx We observed AT2025bcx for 8x 180s starting on 2025-02-10T18:40:45 and performed difference imaging in the r and i band with templates from PS1. In the difference images, we detect a source at the position of AT2025bcx at r = (20.5 +/- 0.2) mag and i = (20.9 +/- 0.3) mag. ### AT2025bmq Additionally, we have observed a list of NED galaxies selected from the list reported by Cook et al. (GCN 39235). We observed the first 11 candidate hosts as ranked by `P_3D_LumW1` in the night starting 2025-02-08. Typical depths in r,i bands are 21.5. Difference imaging w.r.t. PS1 reveals one candidate (AT2025bmq), consistent with being a nuclear transient in a host galaxy that shows previous activity. The r- and i-band magnitudes are calibrated against the PS1 catalog and the J-band is calibrated with the 2MASS Catalog. All magnitudes are provided in the AB system and are not corrected for Galactic extinction. We thank Christoph Ries and Michael Schmid from the Wendelstein Observatory staff for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39311. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37319] EP250207b: VLA radio upper limits
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39310 SUBJECT: EP250207b: VLA radio upper limits DATE: 25/02/13 15:29:42 GMT FROM: Roberto Ricci at INAF-IRA <ricci(a)ira.inaf.it> R. Ricci (U Rome), E. Troja (U Rome) and B. O'Connor (Carnegie Mellon) on behalf of a larger collaboration: We observed the Fast X-ray Transient EP250207b discovered by Einstein Probe (Zhou et al. GCN 39266) at the FXT position (Zhou et al. 39266) with the Very Large Array at the frequency of 6 GHz with a bandwidth of 4 GHz on Feb 12th 07:29 UT mid-time (i.e. 4.40 days after the EP trigger). The primary calibrator was 3C286 and the phase calibrator J1130-1449. The data were calibrated, imaged and analysed in CASA using standard procedures. The target source was not detected in the final cleaned image down to 3-sigma flux upper limit of 21 microJy. We thank the VLA staff for promptly executing the observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39310. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37318] EP250212a: Liverpool Telescope optical upper limits
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39309 SUBJECT: EP250212a: Liverpool Telescope optical upper limits DATE: 25/02/13 08:45:55 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris, P. T. O’Brien and R. L. C. Starling (U of Leicester) report: We observed the field of the X-ray transient EP250212a (Li et al., GCN 39308) with the 2m Liverpool Telescope using the IO:O instrument. We obtained 5x90s exposures in the SDSS g’ filter starting at 2025-02-10 20:59:11 UT and 5x90s exposures in the SDSS r’ filter starting at 2025-02-10 21:08:27 UT, approximately 13.3 hours after the X-ray detection. We performed image subtraction on the stacked images using reference images from Pan-STARRS. Consistent with Malesani et al., (GCN 39306), we identify no new sources within the error region of the EP/FXT candidate. We derive 3-sigma upper limits of g’ > 20.3 and r’ > 21.0 with photometry calibrated to Pan-STARRS and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39309. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37317] EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39308 SUBJECT: EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient DATE: 25/02/13 03:17:51 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. Y. Li (NAOC, CAS), Y. J. Zhang(THU), Y. C. Fu (BNU), W. Yuan (NAOC, CAS) report on behalf of the Einstein Probe team: We report on the detection of a fast X-ray transient by EP-WXT, designated EP250212a (trigger ID: 10202399251). The WXT position of the source is R.A. = 114.949 deg, DEC = 60.493 deg (J2000) with an uncertainty of 2.9 arcmin in radius (90% C.L. statistical and systematic). The transient started at 2025-02-12T07:44:07 (UTC) and lasted for about 360 seconds seen from WXT light curve. The average 0.5-4 keV spectrum can be fitted with an absorbed powerlaw model, with a NH of 0.5 (-0.3, +0.3) x 10^22 cm^-2 and a photon index of 2.2 (-0.9, +1.0). The derived average unabsorbed 0.5-4 keV flux is 0.9 (-0.3, +1.0) x10^-9 erg/s/cm2. The peak flux is about 6 x 10^-9 erg/s/cm2. The average spectrum also can be fitted with an absorbed blackbody model, with a NH upper limit of 0.45 x 10^22 cm^-2 and a temperature of 0.6 (-0.1, +0.2) keV. We performed a follow-up target of opportunity observation with EP-FXT. The observation began at 2025-02-12T13:20:16 (UTC) with an exposure time of 5970 seconds, about 5.6 hours after the burst detected by EP-WXT. Within the WXT error cirlce, an uncatalogued X-ray source was detected at R.A. = 114.9813 deg, DEC = 60.4848 deg (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic). The X-ray spectrum can be fitted with an absorbed powerlaw with the absorption fixed at the Galactic value of 6.3 x 10^20 cm^-2, and a photon index of 2.1 (-0.3, +0.3). The derived unabsorbed 0.5-10 keV flux is 3.2 (-0.7, +0.8) x 10^-13 erg/s/cm2. The uncertainties are at the 90% confidence level for the above parameters. The FXT spectrum can not be well fitted with a black body model. A J-band upper limit of 20.9 mag was given by a NOT observation performed about 12.3 hour after the EP trigger (GCN 39306). 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/39308. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37316] GRB250101A: Radio upper limits from GMRT observations
by GCN Circulars 13 Feb '25

13 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39307 SUBJECT: GRB250101A: Radio upper limits from GMRT observations DATE: 25/02/13 03:05:42 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 al. GCN 38758, Odeh et al. GCN 38763) with the Giant Metrewave Radio Telescope (GMRT) under the DDT (PI: A. Balasubramanian, ddtC419) on 8th February 2025 in band 5 (1.3 GHz) for about 2 hours starting at 13:30 hours UTC. We do not detect any significant radio emission at the position of the optical counterpart (Li et al. GCN 38753). We used 3C48 for the flux calibration and J0238+166 for complex gain and phase calibration. The CASA calibration and imagining CAPTURE-CASA6 pipline was used for data calibration and imaging. We compute a 3-sigma upper limit of ~150 uJy at 1.3 GHz. We thank the GMRT Time Allocation Committee for accepting our DDT proposal and GMRT staff that made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/39307. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37315] EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39306 SUBJECT: EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit DATE: 25/02/12 23:03:14 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud), L. Galbany (ICE-CSIC), K. Phan (ICE-CSIC), B. Hauptmann (NOT and DTU Space) report on behalf of a larger collaboration: We observed the field of the EP trigger 10202399251, which occurred on 2025 Feb 12 (possibly named EP250212a), using the Nordic Optical Telescope (NOT) equipped with the NOTCam near-infrared imager. Observations were conducted in the J band, for a total of 18x60 s exposures, with a mid time of 2025 Feb 12.837 UT (12.3 hr after the EP trigger). Within the error circle of the EP/FXT X-ray counterpart, we detect no new sources down to a limiting magnitude of J = 20.9 (Vega), calibrated against nearby stars from the 2MASS catalog. View this GCN Circular online at https://gcn.nasa.gov/circulars/39306. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37314] EP250207B: GTC Near-Infrared Observations
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39305 SUBJECT: EP250207B: GTC Near-Infrared Observations DATE: 25/02/12 22:09:01 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Yu-Han Yang (U Rome), Rosa L. Becerra (U Rome), Alan M. Watson (UNAM), Eleonora Troja (U Rome), Simone Dichiara (PSU) and Lei Hu (CMU) report on behalf of a larger team: We observed the field of EP250207B detected by EP/WXT (Zhou et al., GCN 39266) with the OSIRIS instrument on the GTC telescope starting at 2025-02-12 05:22 UTC (T+4.31 days after the trigger). We obtained a total integration of 480 seconds (8x60 s) in z with a seeing of about 1.2 arcsec. We performed image subtraction on the stacked images using reference images from the Legacy Survey DR10 (Dey et al. 2019). In our preliminary analysis, we detect artifacts of the image subtraction at the position of the Liverpool Telescope candidate (Eyles-Ferris et al. GCN 39281). However, we do not detect a significant source at this position. In both our data and the Legacy Survey images, we do not detect a source at the right ascension and declination given by Fraser et al. (GCN 39287) and consider that perhaps there is a small error in this stated position. However, we do detect two sources close to their reported position. Both are visible in the Legacy Survey DR10 catalog (Dey et al. 2019) with a photo-z~0.9, and we do not detect any evidence of brightening. Finally, at the position of the NOT candidate reported by Liu et al.,(GCN 39300), we do not detect any source down to a limit of 3-sigma z > 23.8 AB. This value is not corrected for Galactic extinction. Further observations are planned. We thank the staff of the GTC, especially Gianluca Lombardi and Antonio Cabrera, for their help and rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39305. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37313] Fermi GRB 250212A: Global MASTER-Net observations report
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39304 SUBJECT: Fermi GRB 250212A: Global MASTER-Net observations report DATE: 25/02/12 21:16:20 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 GRB 250212A ( Fermi GBM team, GCN 39294) errorbox 69293 sec after notice time and 69339 sec after trigger time at 2025-02-12 20:05:33 UT, with upper limit up to 15.8 mag. The observations began at zenith distance = 46 deg. The sun altitude is -40.0 deg. The galactic latitude b = 21 deg., longitude l = 82 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2775797 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 69341 | 2025-02-12 20:05:33 | MASTER-Tunka | (17h 48m 16.26s , +54d 08m 37.4s) | C | 1 | 15.6 | 69443 | 2025-02-12 20:07:16 | MASTER-Tunka | (17h 47m 16.27s , +56d 03m 20.7s) | C | 1 | 15.8 | 69694 | 2025-02-12 20:11:27 | MASTER-Tunka | (18h 25m 56.36s , +61d 43m 25.6s) | C | 1 | 15.3 | 69939 | 2025-02-12 20:15:31 | MASTER-Tunka | (17h 48m 15.51s , +54d 10m 22.0s) | C | 1 | 15.3 | 70145 | 2025-02-12 20:18:58 | MASTER-Tunka | (17h 47m 19.31s , +56d 03m 48.4s) | C | 1 | 15.6 | 70398 | 2025-02-12 20:23:10 | MASTER-Tunka | (18h 25m 59.43s , +61d 42m 08.6s) | C | 1 | 15.4 | 70557 | 2025-02-12 20:25:50 | MASTER-Tunka | (17h 48m 21.23s , +54d 09m 57.1s) | C | 1 | 15.6 | 70753 | 2025-02-12 20:29:06 | MASTER-Tunka | (17h 47m 14.86s , +56d 04m 17.1s) | C | 1 | 15.2 | 71065 | 2025-02-12 20:34:18 | MASTER-Tunka | (18h 26m 02.66s , +61d 42m 45.1s) | C | 1 | 15.3 | 71229 | 2025-02-12 20:37:02 | MASTER-Tunka | (17h 48m 21.82s , +54d 10m 29.4s) | C | 1 | 15.4 | 71244 | 2025-02-12 20:37:16 | MASTER-Tunka | (18h 15m 35.48s , +54d 07m 19.0s) | C | 1 | 15.2 | 71258 | 2025-02-12 20:37:30 | MASTER-Tunka | (18h 16m 07.40s , +56d 01m 18.4s) | C | 1 | 15.2 | 71268 | 2025-02-12 20:37:41 | MASTER-Tunka | (17h 50m 20.80s , +52d 17m 18.1s) | C | 1 | 15.4 | 71278 | 2025-02-12 20:37:51 | MASTER-Tunka | (17h 53m 18.75s , +50d 21m 26.9s) | C | 1 | 15.4 | 71291 | 2025-02-12 20:38:04 | MASTER-Tunka | (18h 17m 53.75s , +57d 56m 40.2s) | C | 1 | 14.6 | 71307 | 2025-02-12 20:38:19 | MASTER-Tunka | (18h 21m 02.65s , +59d 49m 51.2s) | C | 1 | 14.9 | 71400 | 2025-02-12 20:39:52 | MASTER-Tunka | (17h 47m 19.76s , +56d 03m 54.7s) | C | 1 | 15.1 | 71741 | 2025-02-12 20:45:34 | MASTER-Tunka | (18h 26m 03.43s , +61d 43m 48.0s) | C | 1 | 13.7 | 72033 | 2025-02-12 20:50:25 | MASTER-Tunka | (17h 48m 21.88s , +54d 11m 51.0s) | C | 1 | 12.4 | 72044 | 2025-02-12 20:50:36 | MASTER-Tunka | (18h 15m 41.15s , +54d 07m 56.4s) | C | 1 | 12.3 | 72053 | 2025-02-12 20:50:46 | MASTER-Tunka | (18h 16m 10.34s , +56d 03m 20.5s) | C | 1 | 12.1 | 72065 | 2025-02-12 20:50:57 | MASTER-Tunka | (17h 50m 19.79s , +52d 17m 00.3s) | C | 1 | 12.2 | 72075 | 2025-02-12 20:51:07 | MASTER-Tunka | (17h 53m 17.59s , +50d 23m 48.8s) | C | 1 | 12.2 | 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/39304. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37312] LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39303 SUBJECT: LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber DATE: 25/02/12 19:45:10 GMT FROM: David Coulter at STScI <dcoulter(a)ucsc.edu> D. A. Coulter (STScI), C. D. Kilpatrick (NU), I. Andreoni (UNC), P. Macias (UCSC), R. J. Foley (UCSC), K. W. Davis (UCSC), V. A. Villar (Harvard) reports on behalf of the Gravity Collective [1, 2]: We followed up the reported optical candidate, AT2025ber ([GCN 39286](https://gcn.nasa.gov/circulars/39286)), associated with S250206dm (LVK Collaboration, [GCN 39175](https://gcn.nasa.gov/circulars/39175)), with the ~0.22 square degree field-of-view near-IR imager NEWFIRM mounted on the Blanco 4-m telescope at CTIO, Chile. Our observations began on 2025-02-12 07:22 UTC (+5 days after trigger) and consisted of 40x80s exposures in H-band. Data were processed using standard procedures in photpipe [3]. We do not detect any emission at the site of AT2025ber in forced aperture photometry, and we derive a limiting magnitude of H=23.0 AB mag (3-sigma) at the site of the reported candidate. Our pointing and limit are available in the [GW Treasure Map](https://treasuremap.space/alerts?graceids=S250206dm) [4]. We thank Sean Points, Alberto Alvarez, and CTIO for their support in obtaining these observations. 1. Kilpatrick, C. D. et al. 2021 2. Coulter, D. A., et al. 2024 3. Rest, A. et al. 2005 4. Wyatt, S. D. et al. 2020 View this GCN Circular online at https://gcn.nasa.gov/circulars/39303. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37311] GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39302 SUBJECT: GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit DATE: 25/02/12 17:38:07 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 imaged the field of GRB 250205A detected by SVOM/ECLAIRs telescope (Saccardi et al. GCN 39154), with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3. The observations were started at 2025-02-05 23:12 UT (approximately 1.79 hours after burst) stacking a set of unfiltered CCD image. The observations were carried out with clear skies and good visibility conditions. We co-added 183 exposures of 60 sec each. Start T0+ End T0+ CR lim 1.79 hour 5.88 hour 20.2 We did not found any optical counterpart in the error box of the XRTcandidate. Kennea et al. GCN 39161 Magnitudes were estimated with the PanSTARRS cat. and are not corrected for galactic dust extinction. Our observations are consistent with other already reported Gompertz et al. (GCN 39156), Schneider et al. (GCN 39157), Gompertz et al. (GCN 39158), Palmerio et al. (GCN 39159), A. de Ugarte Postigo et al. (GCN 39160), Watson et al. (GCN 39162), Breeveld et al. (GCN 39168), Busmann et al. (GCN 39169), Ferro et al. (GCN 39170). The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39302. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37310] Fermi trigger No 760945500: Global MASTER-Net observations report
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39301 SUBJECT: Fermi trigger No 760945500: Global MASTER-Net observations report DATE: 25/02/12 17:30:30 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 GRB250211.24 (trigger No 760945500,05h 37m 07.20s , +73d 12m 00.0s, R=1.08) errorbox 1 days 30989 sec after notice time and 1 days 31021 sec after trigger time at 2025-02-12 14:21:57 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 24 deg. The sun altitude is -38.1 deg. The galactic latitude b = 21 deg., longitude l = 140 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2775055 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 117435 | 2025-02-12 14:21:57 | MASTER-Tunka | (05h 31m 57.85s , +73d 40m 33.8s) | C | 25 | 16.5 | 117534 | 2025-02-12 14:23:39 | MASTER-Tunka | (05h 01m 45.40s , +71d 46m 33.1s) | C | 20 | 16.3 | 118179 | 2025-02-12 14:34:29 | MASTER-Tunka | (05h 01m 36.73s , +71d 48m 31.6s) | C | 10 | 16.1 | 118962 | 2025-02-12 14:47:29 | MASTER-Tunka | (05h 15m 12.08s , +75d 35m 19.0s) | C | 15 | 17.5 | 119048 | 2025-02-12 14:48:53 | MASTER-Tunka | (05h 45m 25.39s , +71d 49m 25.5s) | C | 20 | 15.5 | 119984 | 2025-02-12 15:04:31 | MASTER-Tunka | (05h 31m 28.65s , +73d 42m 32.1s) | C | 15 | 16.8 | 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/39301. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37309] EP250207b: NOT optical counterpart candidate
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39300 SUBJECT: EP250207b: NOT optical counterpart candidate DATE: 25/02/12 15:11:09 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> X. Liu, J. An, S.Q. Jiang, S.Y. Fu, Z.P. Zhu, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), M. A. Diaz Teodori, R. H. Rasmussen, A. M. Kadela (NOT) report on behalf of a large collaboration: We observed the field of EP250207b detected by EP/WXT (Zhou et al., GCN39266) using the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A total of 4 x 200 s frames in Sloan r-band were obtained at a mid time of 03:16:13 UT on 2025-02-09, i.e., 1.23 days after the EP trigger time. We performed image subtraction on our stacked image using both PanSTARRS and Legacy Survey images as templates. Within the EP/FXT error circle, an uncatalogued faint source was detected with a magnitude of r ~ 23.7 mag (AB), calibrated against nearby PanSTARRS stars, at coordinates R.A.(J2000) = 11:10:03.21 Dec.(J2000) = -07:52:07.20 with an uncertainty of ~ 1 arcsec. It is about 10 arcsec away from the galaxy WISEA J111002.65-075211.9 noted by Malesani et al. (GCN 39270) and Levan et al. (GCN 39278). The brightness of the galaxy in our image shows no brightening compared to PanSTARRS kron magnitude. In addition, the source reported by Fraser et al. (GCN 39287) is not detected in our stacked image, down to a 5-sigma limiting magnitude of r ~ 23.0 mag (AB). The magnitudes reported above have not been corrected for Galactic extinction. Further observations are planned and deep r-band photometry of the field is encouraged. View this GCN Circular online at https://gcn.nasa.gov/circulars/39300. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37308] GRB 250211A: SVOM trigger sb25021103 is not a GRB
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39299 SUBJECT: GRB 250211A: SVOM trigger sb25021103 is not a GRB DATE: 25/02/12 10:50:31 GMT FROM: F. Fortin at IRAP <ffortin.sci.edu(a)gmail.com> F. Fortin (IRAP), J. Malzac (IRAP), O. Godet (IRAP), M. Brunet (IRAP) report on behalf of the SVOM mission team: The SVOM/ECLAIRs telescope triggered at 2025-02-11T17:50:32 UTC on an uncatalogued source (SVOM trigger sb25021103). After reviewing the ECLAIRs data, we now conclude that sb25021103 is not a GRB but likely an outburst from the Galactic transient LMXB 4U 1604-52. We manually requested a Swift ToO, which was unfortunately requested at an incorrect sky position. Hence, none of the Swift sources from this observation (Evans, GCN 39296) are related to this trigger. We apologize for the inconvenience, and we acknowledge the excellent support from the Swift team for performing the quick ToO. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. The Burst Advocates (BAs) on shift for this trigger are Francis Fortin (francis.fortin(a)irap.omp.eu) and Julien Malzac (julien.malzac(a)irap.omp.eu). Please contact the BA by email if you require additional information regarding the SVOM follow-up of this event. View this GCN Circular online at https://gcn.nasa.gov/circulars/39299. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37307] GRB 250211B: A long GRB detected by INTEGRAL
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39298 SUBJECT: GRB 250211B: A long GRB detected by INTEGRAL DATE: 25/02/12 07:26:35 GMT FROM: Sandro Mereghetti at IASF-Milano/INAF <sandro.mereghetti(a)inaf.it> S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report: a gamma ray burst lasting about 60 s has been detected by IBAS in the IBIS/ISGRI data at 21:27:10 UT of 2025 February 11. The refined coordinates (J2000) are: R.A.= 276.3784 deg DEC.= -31.9655 deg with an uncertainty of 2 arcmin (90% c.l.). The burst had a peak flux of about 0.2 ph/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 4e-7 erg/cmq. A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html View this GCN Circular online at https://gcn.nasa.gov/circulars/39298. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37306] LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39297 SUBJECT: LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT DATE: 25/02/12 02:15:38 GMT FROM: Gregory Paek at Seoul National University <gregorypaek94(a)gmail.com> Gregory S.H. Paek (IfA), Myungshin Im, Mankeun Jeong, Hyeonho Choi, Seo-Won Chang, Ji Hoon Kim, Donggeun Tak, Hongjae Moon (SNU/SNU ARC), Dong-Jin Kim and Chung-Uk Lee (KASI), on behalf of the GECKO team We report ongoing follow-up observations of the LIGO/Virgo/Kagra (LVK) gravitational-wave (GW) event, S250206dm (LVK Collaboration, GCN 39175) with the 7-Dimensional Telescope (7DT) following previous report (Paek et al., GCN 39241). Observations with the 7DT array began on 2025-02-07 at 01:24 UT, roughly four hours after the GW event. Pre-defined tiles were chosen to overlap with the 90% credible region of the GW skymap, and a wide-field search strategy was implemented by assigning each telescope a distinct sky area to maximize coverage. Thirteen 7DT units were employed to sequentially image the region—initially in the g-band and subsequently in the r-band. Per-tile exposure times ranged from 3*100 seconds to 6*100 seconds. Over the two observing epochs from 2025-02-07 (UT) to 2025-02-08 (UT), our observations covered a total of 590 tiles (~590 deg2) in the g-band and 320 tiles (~320 deg2) in the r-band. The achieved 5-sigma depth varied by band, reaching 19.0–21.7 mag in the g-band and 18.4–21.2 mag in the r-band. Notably, following the initial g-band and r-band imaging, two additional epochs of g-band exposures are planned for the updated GW skymap region (LVK Collaboration, GCN 39231)—covering 75 tiles—in coordination with KMTNet’s R- and I-band imaging to ensure comprehensive multi-color coverage. Additionally, a dedicated transient search is scheduled for forthcoming analysis. The coverage of observations is detailed in TreasureMap (Wyatt et al. 2020; https://treasuremap.space/alerts?graceids=S250206dm). The 7-Dimensional Telescope (7DT), located in Chile and comprising 20 wide-field telescopes equipped with 40 medium-bandwidth (~25nm) filters, aims to detect optical counterparts of GW sources and conduct the 7-Dimensional Sky Survey (7DS) of the Southern Hemisphere. Further information about the 7DT is available at https://7ds.snu.ac.kr/ and http://gwuniverse.snu.ac.kr/. View this GCN Circular online at https://gcn.nasa.gov/circulars/39297. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37305] GRB 250211A: Swift ToO observations
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39296 SUBJECT: GRB 250211A: Swift ToO observations DATE: 25/02/12 01:52:54 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the SVOM/ECLAIRs GRB 250211A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021776 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the SVOM/ECLAIRs event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39296. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37304] Integral GRB250211.89: Global MASTER-Net observations report
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39295 SUBJECT: Integral GRB250211.89: Global MASTER-Net observations report DATE: 25/02/12 01:19:50 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.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) was pointed to the Integral GRB250211.89 (trigger No 11044,18h 25m 33.49s , -31d 57m 36.2s, R=0.0533333) errorbox 12195 sec after notice time and 12210 sec after trigger time at 2025-02-12 00:51:28 UT, with upper limit up to 16.7 mag. The observations began at zenith distance = 81 deg. The sun altitude is -36.1 deg. The galactic latitude b = -10 deg., longitude l = 2 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2775663 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 12300 | MASTER-SAAO | C | 180 | 16.1 | 12480 | MASTER-SAAO | C | 540 | 15.8 | Coadd 12500 | MASTER-SAAO | C | 180 | 16.2 | 12699 | MASTER-SAAO | C | 180 | 16.4 | 12904 | MASTER-SAAO | C | 180 | 16.4 | 13103 | MASTER-SAAO | C | 180 | 16.5 | 13302 | MASTER-SAAO | C | 180 | 16.6 | 13502 | MASTER-SAAO | C | 180 | 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/39295. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37303] GRB 250212A: Fermi GBM Final Real-time Localization
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39294 SUBJECT: GRB 250212A: Fermi GBM Final Real-time Localization DATE: 25/02/12 01:00:30 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 00:49:53 UT on 12 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250212A (trigger 761014198.925334 / 250212035). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 282.5, Dec = 52.8 (J2000 degrees, equivalent to J2000 18h 49m, 52d 47'), with a statistical uncertainty of 8.1 degrees. The angle from the Fermi LAT boresight is 127.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250212035/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250212035/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250212035/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39294. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37302] LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
by GCN Circulars 12 Feb '25

12 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39293 SUBJECT: LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST DATE: 25/02/12 00:33:45 GMT FROM: Zhengyan Liu at USTC <ustclzy(a)mail.ustc.edu.cn> Z. L. Xu, D. Z. Meng, Z. Y. Liu, J.-A. Jiang, W. Zhao, M. X. Cai, T. G. Wang, X. Kong, Z. G. Dai, L. L. Fan (USTC), Y. Z. Fan, J. J. Geng, Z. P. Jin, X. F. Wu (PMO) report on behalf of the WFST Collaboration: We conducted follow-up observations of gravitational wave event S250206dm (the LIGO-Virgo-Kagra Collaboration, GCN 39175) using the Wide Field Survey Telescope (WFST Collaboration; Wang et al., 2023). Our follow-up observations (Liu et al, GCN 39249) in r and i bands covered the region of AT2025bbo (Smartt et al, GCN 39244). Additionally, after checking WFST archive data, we found that one 60s r-band exposure (a 5-sigma limiting magnitude of 22.02) taken at 2025-01-12T13:57:44 UTC covered the region as well. We performed image subtraction for WFST r-band images from 2025-02-07T14:23:27 UTC using the 2025-01-12 exposure as template, and for WFST i-band images using the first exposure taken at 2025-02-07T13:50:35 UTC as template. After image subtraction, we do not found any residuals in all difference images in two bands, suggesting that AT2025bbo is unlikely a transient occured aftet the GW event S250206dm (also see Chen et al, GCN 39285). View this GCN Circular online at https://gcn.nasa.gov/circulars/39293. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37301] LIGO/Virgo/KAGRA S250211be: Updated Sky localization
by GCN Circulars 11 Feb '25

11 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39292 SUBJECT: LIGO/Virgo/KAGRA S250211be: Updated Sky localization DATE: 25/02/11 23:06:19 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 (CBC) candidate S250211be (GCN Circular 39277). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250211be For the Bilby.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 94 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(11h45m, +25d11m, 8.14d, 3.67d, 84.71d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3337 +/- 1194 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380 View this GCN Circular online at https://gcn.nasa.gov/circulars/39292. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37300] GRB 250207A: Fermi GBM Observation
by GCN Circulars 11 Feb '25

11 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39291 SUBJECT: GRB 250207A: Fermi GBM Observation DATE: 25/02/11 21:31:46 GMT FROM: oindabimukherjee(a)gmail.com O. Mukherjee (USRA), R. Hamburg (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 01:16:03.15 UT on 07 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250207A (trigger 760583768/250207053). which was also detected by Swift BAT (Ferro et al. 2025, GCN 39182), COLIBRÍ/DDRAGO (Angulo et al. 2025, GCN 39186), Swift/UVOT (Kuin et al. 2025, GCN 39199), and Konus-Wind (Ridnaia. et al. 2025, GCN 39284) The Fermi GBM Final Real-time Localization (GCN 39181) is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 46 degrees. The GBM light curve consistes of a single emission episode with multiple peaks with a duration (T90) of about 20 s (50-300 keV). The time-averaged spectrum from T0-3.1 to T0+25.6 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.10 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 290 +/- 30 keV. The event fluence (10-1000 keV) in this time interval is (1.04 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+12 s in the 10-1000 keV band is 4.7 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 240 +/- 30 keV, alpha = -1.03 +/- 0.08 and beta = -2.3 +/- 0.3. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/39291. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37299] GRB 250206A: Fermi GBM Observation
by GCN Circulars 11 Feb '25

11 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39290 SUBJECT: GRB 250206A: Fermi GBM Observation DATE: 25/02/11 20:44:49 GMT FROM: oindabimukherjee(a)gmail.com O. Mukherjee (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 19:51:31.93 UT on 06 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250206A (trigger 760564296/250206827). which was also detected by Fermi-LAT (Gupta et al. 2025, GCN 39233) and Konus-Wind (Ridnaia et al. 2025, GCN 39283). The Fermi GBM on-ground location is consistent with the Fermi-LAT position. The angle from the Fermi LAT boresight is 33 degrees. The GBM light curve consists of a multipeaked emission episode followed by a single peaked emission episode with a duration (T90) of about 64.3 s (50-300 keV). The time-averaged spectrum from T0-2.0 to T0+79.9 s is best fit by a Band function with Epeak = 187 +/- 8 keV, alpha = -0.73 +/- 0.04, and beta = -2.6 +/- 0.2. The event fluence (10-1000 keV) in this time interval is (2.66 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.7 s in the 10-1000 keV band is 10.4 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/39290. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37298] GRB 250205A / EP250205A: radio detection with the VLA
by GCN Circulars 11 Feb '25

11 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39289 SUBJECT: GRB 250205A / EP250205A: radio detection with the VLA DATE: 25/02/11 16:51:06 GMT FROM: Stefano Giarratana at INAF-OAB <s.giarratana(a)ira.inaf.it> S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.), O. S. Salafia (INAF-OAB) At 08:59:34 UT on 2025 Feb 7 (T_mid = 1.51 days post-burst) the Karl G. Jansky VLA observed the field of GRB 250205A / EP250205A (Saccardi et al., GCN 39154; Mukherjee et al., GCN 39171) in three bands, with central frequencies of 6, 10 and 15 GHz. The standard 3C286 was used as bandpass and flux density calibrator, while J0741+3112 was used as phase calibrator. From a preliminary analysis, an unresolved radio source is detected at a position (J2000): RA: 07:34:02.649 +- 0.003 Dec: 32:22:18.84 +- 0.05 consistent with the X-ray (Kennea et al., GCN39161; Liu et al., GCN 39165) and optical (Gompertz et al., GCN 39156; Palmerio et al., GCN 39159; de Ugarte Postigo et al., GCN 39160; Watson et al., GCN 39162; Busmann et al., GCN 39169) position of the transient. The preliminary analysis yields the following results: ================================================================ T_mid Freq Peak r.m.s. Beam PA [days] [GHz] [uJy/b] [uJy/b] [arcsec^2] [deg] ================================================================ 1.51 6 27 7 0.49x0.32 66 1.51 10 44 8 0.32x0.19 65 1.51 15 40 7 0.19x0.13 66 ================================================================ No source is detected with a >3sigma confidence at the aforementioned position in previous radio surveys (NVSS, FIRST, VLASS), all of which have r.m.s. noise levels above 100 uJy/b. We would like to thank the staff of the VLA for approving, executing, and processing the observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. These observations were carried out as part of project SF171028, approved in the framework of the Fermi - NRAO joint program agreement. View this GCN Circular online at https://gcn.nasa.gov/circulars/39289. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37297] IceCube-250207A: One candidate from the Zwicky Transient Facility
by GCN Circulars 11 Feb '25

11 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39288 SUBJECT: IceCube-250207A: One candidate from the Zwicky Transient Facility DATE: 25/02/11 16:35:05 GMT FROM: Jannis Necker at DESY <jannis.necker(a)desy.de> Jannis Necker, Akshay Eranhalodi (DESY), Robert Stein (JSI), Sven Weimann (Ruhr University Bochum), and Anna Franckowiak (Ruhr University Bochum) report: On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: As part of the ZTF neutrino follow up program (Stein et al. 2023), we observed the localization region of the neutrino event IceCube-250207A (Sommani et. al, GCN 39203) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-02-08 06:52 UTC, approximately 28.7 hours after event time. We covered 98.9% (9.8 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019) . We are left with the following high-significance transient candidate by our pipeline, lying within the 90.0% localization of the skymap. +--------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr | +--------------------------------------------------------------------------------+ | ZTF25aafgnar | ------- | 131.6422069 | +19.3306551 | r | 20.68 | 0.16 | +--------------------------------------------------------------------------------+ ZTF25aafgnar was first detected on 2025-01-19. The source is somewhat red, with a g-r colour of 0.3. Due to the offset of 0.92 arcsec from the nucleus of its host SDSS J084634.07+191950.9, it appears most likely to be a supernova. Forced photometry reveals ZTF pre-detections beginning on 2025-01-19, demonstrating that the supernova predates the detection of IC250207A. The source reached a peak magnitude of m=20.2 in g-band on 2025-01-23, and has since faded by 0.5 mag. Photometric redshift estimates for the host galaxy from Legacy Survey suggest a distance of z = 0.26 +/- 0.06, with a 95% lower limit of z>0.165, implying a peak absolute magnitude of at least M<-19.4. The colour and implied absolute magnitude are consistent with a supernova origin for this source. The timing of the neutrino detection excludes any choked-jet neutrino production models, but CSM-interaction neutrino production models would still be viable. Spectroscopic observations are planned to determine the nature of this transient. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA; WIS, Israel; OKC, Sweden; JSI/UMd, USA; DESY, Germany; TANGO, Taiwan; UW Milwaukee, USA; LANL, USA; TCD, Ireland; IN2P3, France. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). Alert filtering is performed with the nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ). View this GCN Circular online at https://gcn.nasa.gov/circulars/39288. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37296] EP250207b: Tentative z-band brightening source
by GCN Circulars 11 Feb '25

11 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39287 SUBJECT: EP250207b: Tentative z-band brightening source DATE: 25/02/11 16:01:30 GMT FROM: Andrew Levan at Radboud University <a.levan(a)astro.ru.nl> Morgan Fraser (UCD), Andrew J. Levan (Radboud), Daniele B. Malesani (DAWN/NBI and Radboud), Peter G. Jonker (Radboud), Jonathan A. Quirola-Vásquez (Radboud), Javi Sánchez-Sierras (Radboud), Franz E. Bauer (PUC), Antonio Martin-Carrillo (UCD), report on behalf of a larger collaboration: We report on Gemini North + GMOS observations of the localisation region of the fast X-ray transient EP250207b (Zhou et al., GCN 39266). 6x60 s images were taken in z-band on 2025 Feb. 10 (MJD 60716.44; Malesani et al., GCN 39270) and 5x60 s on Feb. 11 (MJD 60717.48). Performing image subtraction between the two average z-band images, we see a marginal transient in the difference image that has brightened between the two epochs, located at coordinates: RA(J2000) = 11:10:02.8 Dec(J2000) = -07:52:05.8. A source is present at the transient location in both z-band epochs as well as in the Legacy survey. Aperture photometry of the object in the two epochs is consistent with a modest brightening by 0.25 +/- 0.10 mag between the two epochs. The position of the source is offset by about 6.5" to the north of the WISEA J111002.65-075211.9 nucleus, the z=0.082 galaxy that lies within the error circle of EP250207b (Malesani et al., GCN 39270; Levan et al., GCN 39278). If the brightening of this source is real, the association with WISEA J111002.65-075211.9 becomes less clear, and the distance of this event would remain undetermined. We do not see any evidence for transient emission in z-band at the location of the source identified by Eyles-Ferris et al. (GCN 39281) in our subtractions, but we note that the central regions of WISEA J111002.65-075211.9 are subject to substantial uncertainties due to subtraction residuals. Further observations of this field are planned to establish the reality of this object. We thank the staff of Gemini for their excellent support in securing these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39287. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37295] LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
by GCN Circulars 11 Feb '25

11 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39286 SUBJECT: LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient DATE: 25/02/11 15:01:05 GMT FROM: James Freeburn at Swinburne University of Technology <jamesfreeburn54(a)gmail.com> James Freeburn (Swinburne/OzGrav), Sarah Teague (UNC), Jonathan Carney (UNC), Igor Andreoni (UNC), Charles Kilpatrick (Northwestern), Olga Volchansky (UMD), Andre Santos (CBPF), Clecio De Bom (CBPF): We continued (Freeburn et al., GCN 39196) follow up observations of the gravitational wave trigger S250206dm (GCN 39175, GCN 39178, GCN 39184, GCN 39231) using the Goodman High Throughput Spectrograph mounted on the SOAR 4.1-meter telescope in imaging mode via Target of Opportunity observations (PI Andreoni). We observed 30 galaxies in the highest probability region (Cook at al. GCN 39174, GCN 39177, GCN 39185, GCN 39235) using the list produced by crossmatching the sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023). Specifically, we considered the galaxy list obtained using the LVK S250206dm-7-Update sky localization (Cook at al. GCN 39235), focusing on the Southern high probability area. Observations were acquired from 2025-02-09 06:48 UT until 09:18 UT. Each galaxy was observed with 3 x 60s exposures in i-band which resulted in a typical depth of ~22 AB magnitude. We used the SOAR/Goodman observations from 2025-02-07 (Freeburn et al. GCN 39196) as science images and the observations from 2025-02-09 as templates. From a preliminary analysis of the resultant difference images, we find one low significance candidate, AT2025ber, at 16:31:50.40 -69:31:44.29, in the 51% localisation contour of the S250206dm updated skymap. It is in the vicinity of the NED-LVS galaxy WISEA J163202.83-693109.0, which is a galaxy with a spectroscopic redshift of z=0.07743 and a luminosity distance of 354.7 Mpc. The separation distance between WISEA J163202.83-693109.0 and AT2025ber is ~100kpc. Given this large separation distance, it is unlikely that WISEA J163202.83-693109.0 is the host galaxy to AT2025ber, but such a large separation would not be unprecedented for a compact binary merger (see, e.g., Fong et al. 2013). The photometry is provided below in AB magnitudes: 2025-02-07 i = 22.0 +/- 0.2 g > 22.4 2025-02-09 i > 22.2 From MPChecker, we do not find any known asteroid associated with AT2025ber. However, given the brightness of this event, and the fact that it was found in a single image, we caution the possibility that this is an uncatalogued asteroid. There is no coincident source in archival DELVE data (Drlica-Wagner et al., 2021) which places upper limits in gri > 23.5 AB mag. A list of the observed galaxies which are still within the 90% probability volume is presented in the table below. The completed pointings were uploaded to TreasureMap: https://treasuremap.space/alerts?graceids=S250206dm object_name coordinates WISEA J161708.84-674024.7 16:17:08.87 -67:40:22.49 WISEA J162759.57-693615.7 16:27:59.57 -69:36:15.71 WISEA J154439.56-665529.0 15:44:39.56 -66:55:29.08 WISEA J155633.83-693531.5 15:56:33.83 -69:35:31.55 WISEA J160843.41-685023.4 16:08:43.41 -68:50:23.44 WISEA J160915.94-690504.9 16:09:15.95 -69:05:04.94 WISEA J161332.77-674621.1 16:13:32.78 -67:46:21.13 WISEA J165614.58-695645.9 16:56:14.58 -69:56:46.00 WISEA J163330.53-670950.7 16:33:30.54 -67:09:50.72 WISEA J154538.24-703944.1 15:45:38.25 -70:39:44.12 WISEA J153057.77-694546.5 15:30:57.77 -69:45:46.58 WISEA J160838.27-700230.8 16:08:38.27 -70:02:30.85 WISEA J161213.79-710729.1 16:12:13.79 -71:07:29.14 WISEA J165744.21-680430.9 16:57:44.21 -68:04:30.93 WISEA J163202.83-693109.0 16:32:02.84 -69:31:09.01 WISEA J164922.44-690054.7 16:49:22.44 -69:00:54.76 WISEA J161735.32-701416.0 16:17:35.32 -70:14:16.00 WISEA J163253.56-702946.2 16:32:53.57 -70:29:46.22 ESO 069- G 003 16:24:32.07 -68:49:12.91 WISEA J161946.23-690837.2 16:19:46.23 -69:08:37.26 WISEA J155653.84-695749.1 15:56:53.88 -69:57:49.18 WISEA J165438.30-670413.8 16:54:38.30 -67:04:13.82 WISEA J163224.97-700239.7 16:32:24.97 -70:02:39.78 WISEA J155231.27-695346.6 15:52:31.31 -69:53:46.61 WISEA J155145.65-695137.1 15:51:45.63 -69:51:36.90 WISEA J154932.61-695540.7 15:49:32.96 -69:55:41.02 WISEA J160323.17-681358.2 16:03:23.27 -68:14:00.31 WISEA J160100.07-690900.0 16:01:00.10 -69:09:00.00 WISEA J161133.67-692644.0 16:11:33.73 -69:26:43.58 WISEA J161459.65-691110.1 16:15:05.66 -69:11:09.89 We thank the NOIRLab and SOAR staff for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/39286. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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