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

[vsnet-grb-info 37780] GRB 250317B: REM optical/NIR observations
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39764 SUBJECT: GRB 250317B: REM optical/NIR observations DATE: 25/03/17 15:27:41 GMT FROM: Matteo Ferro at INAF-OAB <matteo.ferro(a)inaf.it> M. Ferro, R. Brivio, S. Covino, P. D'Avanzo, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of the SVOM GRB 250317B (Zhao et al., GCN 39752 & GCN 39753; Götz et al. GCN 39756) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, J, H, and K bands, started on 2025 March 17 at 03:44:41 UT (i.e. 1.54 hr after the burst), and lasted for about 3 hours. From preliminary inspection, we detected the NIR counterpart at the position of the reported optical afterglow (Watson et al., GCN circ. 39754; Palmerio et al., GCN circ. 39755; Pérez-Fournon et al., GCN 39757; Ghosh et al., GCN 39759), with the following magnitude: H = 15.5+-0.3 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 1.62 hours after the trigger. The afterglow is not detected in our r-band observations down to the following 3sigma limit: r > 18.0 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 3.05 hours after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/39764. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37779] GRB 250317B: Swift-XRT observations
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39763 SUBJECT: GRB 250317B: Swift-XRT observations DATE: 25/03/17 15:05:53 GMT FROM: Andrea Melandri at INAF-OAR <andrea.melandri(a)inaf.it> A. Melandri (INAF-OAR), V. D'Elia (SSDC & INAF-OAR), E. Ambrosi, A. D'Ai (INAF-IASFPA) , 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 GRB 250317B (Zhao et al., GCN circ. 39752 and GCN circ. 39753) and SVOM/MXT (Götz et al., GCN circ. 39756), collecting 1.7 ks of Photon Counting (PC) mode data between T0+10.0 ks and T0+12.9 ks (SVOM burst-id sb25031701). One uncatalogued X-ray source has been detected within the estimated 3-sigma SVOM/MXT error region (Götz et al., GCN circ. 39756), consistent with the optical counterpart (Watson et al., GCN 39754). The source is fading with 3.0-σ significance. Details of this source are given below: Source 1: RA (J2000.0): 211.6427 = 14:06:34.3 Dec (J2000.0): +40.0796 = +40:04:46.7 Error: 3.0 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.19 (±0.04) ct s-1 Flux: 3.7 (±0.4) ×10-12 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/SVOM/SVOM_FIELD00003/. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39763. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37778] GRB 250316A: Swift/UVOT Upper Limits
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39762 SUBJECT: GRB 250316A: Swift/UVOT Upper Limits DATE: 25/03/17 13:26:57 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: Swift/UVOT observed the field of GRB250316A (GCN 39737) for a total of 3.3 ks in the white filter from 21.8 ks to 29 ks after the Fermi trigger. We detect no optical/UV source at the position of the XRT afterglow (Beardmore et al., GCN Circ. 39758) to an upper limit of white > 22.53. The magnitude is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.017 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/39762. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37777] GRB 250314A: REM optical/NIR upper limits
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39761 SUBJECT: GRB 250314A: REM optical/NIR upper limits DATE: 25/03/17 13:09:40 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro, S. Covino, P. D'Avanzo, S. Campana (INAF-OAB), D. B. Malesani (DAWN/NBI and Radboud), A. Melandri (INAF-OAR), D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of the SVOM GRB 250314A (Wang et al., GCN 39719), followed-up by Swift/XRT (Kennea et al., GCN 39734) and EP/FXT (Turpin et al., GCN 39739), with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, J, H, and K bands, started on 2025 March 15 at 01:18:28 UT (i.e. 12.4 hr after the burst), and lasted for about 1 hour. From preliminary inspection, we do not find any counterpart at the position of the reported NIR afterglow (Malesani et al., GCN 39727; Malesani et al., GCN 39732) down to the following 3sigma limits: r > 18.1 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 12.9 hours after the trigger, H > 16.1 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 12.8 hours after the trigger, J > 16.8 (Vega; calibrated against the 2MASS catalogue) at a mid-time of 13.0 hours after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/39761. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37776] GRB 250316A: AbAO AS-32 Optical Upper Limit
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39760 SUBJECT: GRB 250316A: AbAO AS-32 Optical Upper Limit DATE: 25/03/17 12:43:30 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 250316A (The Fermi GBM team, GCN 39741; Ronchini et. al, GCN 39744; Evans, GCN 39745; Lipunov et. al, GCN 39747; Kennea et. al, GCN 39750; Bala & Meegan, GCN 39751; Beardmore et. al, GCN 39758) in the R filter with the 0.7-meter AS-32 telescope of the Abastumani Astrophysical Observatory (AbAO). The observations started on (UT) 2025-03-17 00:17:41, i.e. about 0.67 days since trigger. We do not find any new optical source within the error circle of the most probable candidate afterglow Swift XRT #1 (Beardmore et. al, GCN 39758). The preliminary upper limit is as follows: Date UT start t-T0 Exp. Filter OT UL(3sigma) (mid, days) (s) 2025-03-17 00:17:41 0.67447 107*60 R n/d 19.7 The photometry is based on nearby stars from the USNO-B1.0 catalog (R2 magnitudes) and has not been corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39760. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37775] EP 250317B: Fading optical counterpart detection by LCO
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39759 SUBJECT: EP 250317B: Fading optical counterpart detection by LCO DATE: 25/03/17 11:21:28 GMT FROM: ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994(a)gmail.com> Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES), Rahul Gupta (NASA GSFC) on behalf of a larger collaboration. We observed the field of the GRB 250317B triggered by SVOM/ECLAIRs (Zhao et al., GCN circ. 39752 and GCN circ. 39753) and SVOM/MXT(Zhao et al., GCN circ. 39752 and GCN circ. 39753; and Götz et al., GCN circ. 39756) in r filter of the 0.4-m SCICAM QHY600 at the Las Cumbres Observatory Global Telescope (LCOGT) node located at Haleakala Observatory, Hawai . The 0.4 m SCICAM QHY600 is equipped with 9576 x 6388 pixel CCD (FOV: 1.9 x 1.2 degrees, scale: 0.74 arcsec/pixel) but we only used the FOV of 30 x 30 arcmin for our observation. Observations began on March 17, 2025, starting 6.46 hours after the GRB trigger. We clearly detect the optical transient (OT) reported by GCNs (Watson et al., GCN circ. 39754, Palmerio et al., GCN circ. 39755, Pérez-Fournon et al., GCN 39757) in our r band image. |Date| |UTstart| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude| -------------------------------------------------------------------------------------------------- 2025-03-17 08:39:27.93 6.46 2 x 300 r r = 19.48 +/- 0.11 The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39759. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37774] GRB 250316A: Swift-XRT afterglow detection
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39758 SUBJECT: GRB 250316A: Swift-XRT afterglow detection DATE: 25/03/17 09:48:06 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , 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 conducted further observations of the field of the Swift/BAT-detected burst GRB 250316A. The observations now extend from T0+21.7 ks to T0+51.0 ks and have a total exposure time of 4.6 ks. . The source previously reported, "Source 1", is believed to be the afterglow. Using 3006 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 219.59644, +14.89108 which is equivalent to: RA (J2000): 14h 38m 23.15s Dec(J2000): +14d 53' 27.9" with an uncertainty of 3.0 arcsec (radius, 90% confidence). This position is 118 arcsec from the Swift/BAT position. The source is fading with alpha >0.9. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.7 (+0.9, -0.7). The best-fitting absorption column is 5.1 (+4.0, -2.8) x 10^21 cm^-2, in excess of the Galactic value of 1.5 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 3.0 x 10^-11 (8.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 5.1 (+4.0, -2.8) x 10^21 cm^-2 Galactic foreground: 1.5 x 10^20 cm^-2 Excess significance: 2.9 sigma Photon index: 2.7 (+0.9, -0.7) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021823. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021823. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39758. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37773] GRB 250317B: LCO detection of the fading optical afterglow
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39757 SUBJECT: GRB 250317B: LCO detection of the fading optical afterglow DATE: 25/03/17 09:34:57 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> I. Pérez-Fournon, F. Poidevin (IAC and ULL), D. Cano-Morales, I. Correa-Plasencia, and A.E. Hernández-Díaz (ULL) We report Las Cumbres Observatory Global Telescope network (LCOGT) observations of the field of GRB 250317B, discovered by SVOM/ECLAIRs (Zhao et al., GCN circ. 39752 and GCN circ. 39753) and SVOM/MXT (Zhao et al., GCN circ. 39752 and GCN circ. 39753; and Götz et al., GCN circ. 39756). We observed the field of GRB 250317B with one of the two LCOGT 1-m telescopes, equipped with Sinistro cameras, located at the LCOGT node at McDonald Observatory (Texas). We obtained a 300-sec exposure in the SDSS r' filter starting at 2025-03-17 07:26:01 UT, about 5.23 hours after the SVOM trigger. An uncatalogued source is clearly detected at the position of the optical afterglow detected by SVOM/F-GFT (COLIBRÍ) (Watson et al., GCN circ. 39754) and SVOM/VT (Palmerio et al., GCN circ. 39755). We measure the following AB magnitude, calibrated against Pan-STARRS DR2 stars and not corrected for Galactic extinction: Time (UT, mid term) | mag | error | filter | ---------------------------------------------- 2025-03-17T07:28:31 19.27 0.05 r' 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/39757. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37772] GRB 250317B: refined SVOM/MXT analysis
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39756 SUBJECT: GRB 250317B: refined SVOM/MXT analysis DATE: 25/03/17 08:04:00 GMT FROM: Diego Gotz at CEA <diego.gotz(a)cea.fr> D. Götz (CEA), F. Robinet (IJCLab), H. Goto (CEA), C. Plasse (CEA), P. Maggi (ObAS), M. Moita (CEA), C. van Hove (IJCLab) on behalf of the MXT team report: We performed further analysis of the GRB 250317B (Zhao et al., GCN 39753) MXT X-ray data, using promptly downloaded photons through the VHF band. We can improve the X-ray afterglow position. The new J2000 coordinates are R.A. = 14h 06m 32s Dec. = +40d 05mm 02ss with a 90% c.l. error radius of 48 arc seconds, including systematics. This position supersedes the one reported in GCN 39753, which was affected by early satellite instability after the slew. We note that this position is consistent with the SVOM/F-GFT (COLIBRÍ) position (Watson et al. GCN 39754) and the VT one (Palmeiro et al. GCN 39755). 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. MXT has been developed by CNES in collaboration with CEA, IJCLab, University of Leicester and MPE. View this GCN Circular online at https://gcn.nasa.gov/circulars/39756. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37771] GRB250317B: SVOM/VT detection of an optical candidate from VHF data
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39755 SUBJECT: GRB250317B: SVOM/VT detection of an optical candidate from VHF data DATE: 25/03/17 06:48:34 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> J. T. Palmerio (CEA) reports on behalf of the SVOM/VT team: After the trigger by SVOM/ECLAIRs at 2025-03-17T02:12:08 UTC (Tb), SVOM performed an automatic slew on the burst. SVOM/VT began observing the field at 2025-03-17T02:18:21, 362 seconds after the SVOM trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. An uncatalogued source is detected within the error box of SVOM/ECLAIRs (Zhao et al. GCN 39753) using the VT VHF pipeline at ra=211.643617, dec=40.079524 (J2000), corresponding to: RA (J2000) = 14h06m34.5s Dec (J2000) = +40:04:46.3s with an uncertainty of 0.5 arcsec. consistent with the optical afterglow reported by Watson et al. (GCN 39754) The source is detected in both VT_R and VT_B and was fading between the third and fourth VT observing sequences (starting at 5574 and 8474 seconds after the trigger respectively), the magnitudes are given below: date-obs | exposure time (s) | mag(AB) | mag err | band 2025-03-17T03:45:13 | 6x50 | 17.48 | 0.02 | VT_R 2025-03-17T04:33:33 | 5x50 | 17.82 | 0.01 | VT_R 2025-03-17T03:45:13 | 6x50 | 18.89 | 0.01 | VT_B 2025-03-17T04:33:33 | 5x50 | 18.97 | 0.02 | VT_B The source was undetected in the first two sequences (starting at 362 and 512 seconds after the trigger, respectively) and is outside the reported SVOM/MXT position. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/39755. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37770] GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39754 SUBJECT: GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart DATE: 25/03/17 06:31:31 GMT FROM: Sarah Antier at OCA <sarah.antier(a)oca.eu> Alan M. Watson (UNAM), Sarah Antier (OCA/IJCLAB), Jean-Luc Atteia (IRAP), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Antonio de Ugarte Postigo (LAM), Benjamin Schneider (LAM) and C. Wu (NAOC) report: We imaged the field of the SVOM/ECLAIRs GRB 250317B (Zhao et al. GCN Circ. 39752, Zhao et el. GCN Circ. 39753) with the OGSE test camera imager on the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-03-17 04:21 to 04:56 UTC (2.15 to 2.73 hours after the trigger) and obtained 23 minutes of exposure in the r filter at high airmass. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2024), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our photometry is in the AB system and is not corrected for Galactic extinction. We detect an uncatalogued source at RA = 211.64367 degrees and Dec = 40.07953 degrees (J2000) with a magnitude of r = 18.18 +/- 0.03 The source is observed to fade in later observations and is not present in Legacy Survey DR10, which strongly suggests it is the afterglow of the GRB. This source is 81 arcsec from the MXT position reported by Zhao et al. (GCN Circ. 39752) and significantly beyond the reported 25 arcsec 90% confidence radius. Further observations are planned. We acknowledge excellent support from the staff of the Observatorio Astronómico Nacional. View this GCN Circular online at https://gcn.nasa.gov/circulars/39754. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37769] GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39753 SUBJECT: GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752 DATE: 25/03/17 05:29:56 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Donghua Zhao, Yinuo Ma, Wenjin XIE(NAOC), Li Zhang (IHEP), F. Robinet (IJCLab), Liping Xin (NAOC) on behalf of the SVOM mission team. At 2025-03-17T02:12:08 UTC (Tb) SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250317B (SVOM burst-id sb25031701). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 13 alerts. CRT provided the alert with the best signal-to-noise-ratio (SNR) of 14.27 in the [5-8] keV energy band over a time window of 40.96 seconds starting at Tb. The light curve showed a broad peak structure with a T90 duration of about 145.67 (-0.16 +0.16). The localization of the best alert is R.A., Dec 211.665, 40.056 degrees (J2000) with a 90% C.L. radius of 5.75 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. MXT began observing the field at 2025-03-17T02:14:36 UTC, 148 seconds after Tb. Using onboard processed data we found a bright and rapidly fainting uncatalogued X-ray source located at R.A., Dec 211.648, 40.057 degrees: RA (J2000) = 14h06m35s DEC (J2000) = 40d03m23s with a 90% C.L. radius of 25 arcseconds. This location is 48 arcseconds away from the ECLAIRs onboard position. VT began to observe the field after the slew. No uncatalogued sources were detected within MXT errors compared to DESI catalog based on the VHF sequences. The 3 sigma limit magnitude is about VT_R~21 mag (AB) at about 10 minutes after the trigger. More analysis will be performed after receiving the X band data later. 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 Donghua Zhao (zhaodh(a)bao.ac.cn). Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst. We apologize for any confusion and inconvenience caused by this mistake. View this GCN Circular online at https://gcn.nasa.gov/circulars/39753. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37768] GRB 250317A: SVOM detection of a burst
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39752 SUBJECT: GRB 250317A: SVOM detection of a burst DATE: 25/03/17 03:38:10 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Donghua Zhao, Yinuo Ma, Wenjin XIE(NAOC), Li Zhang (IHEP), F. Robinet (IJCLab), Liping Xin (NAOC) on behalf of the SVOM mission team. At 2025-03-17T02:12:08 UTC (Tb) SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250317A (SVOM burst-id sb25031701). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 13 alerts. CRT provided the alert with the best signal-to-noise-ratio (SNR) of 14.27 in the [5-8] keV energy band over a time window of 40.96 seconds starting at Tb. The light curve showed a broad peak structure with a T90 duration of about 145.67 (-0.16 +0.16). The localization of the best alert is R.A., Dec 211.665, 40.056 degrees (J2000) with a 90% C.L. radius of 5.75 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. MXT began observing the field at 2025-03-17T02:14:36 UTC, 148 seconds after Tb. Using onboard processed data we found a bright and rapidly fainting uncatalogued X-ray source located at R.A., Dec 211.648, 40.057 degrees: RA (J2000) = 14h06m35s DEC (J2000) = 40d03m23s with a 90% C.L. radius of 25 arcseconds. This location is 48 arcseconds away from the ECLAIRs onboard position. VT began to observe the field after the slew. No uncatalogued sources were detected within MXT errors compared to DESI catalog based on the VHF sequences. The 3 sigma limit magnitude is about VT_R~21 mag (AB) at about 10 minutes after the trigger. More analysis will be performed after receiving the X band data later. 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 Donghua Zhao (zhaodh(a)bao.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/39752. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37767] GRB 250316A: Fermi GBM Observation
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39751 SUBJECT: GRB 250316A: Fermi GBM Observation DATE: 25/03/17 03:14:06 GMT FROM: sumanbala2210(a)gmail.com S. Bala (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 08:59:57.69 UT on 16 March 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250316A (trigger 763808402/250316375). which was also detected by Swift/BAT-GUANO (Ronchini et al. 2025, GCN 39744). The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position. The angle from the Fermi LAT boresight is 98 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 38.7 s (50-300 keV). The time-averaged spectrum from T0-3.1 to T0+46.1 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.2 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 110 +/- 10 keV. The event fluence (10-1000 keV) in this time interval is (4.7 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+16 s in the 10-1000 keV band is 3.5 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 80 +/- 10 keV, alpha = -1 +/- 0.2 and beta = -2.3 +/- 0.2. 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/39751. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37766] GRB 250316A: Swift-XRT observations
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39750 SUBJECT: GRB 250316A: Swift-XRT observations DATE: 25/03/17 00:35:45 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , 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 Swift/BAT GUANO-detected burst GRB 250316A (GCN #39744), collecting 4.3 ks of Photon Counting (PC) mode data between T0+21.5 ks and T0+46.5 ks. One uncatalogued X-ray source has been detected within the estimated 3-sigma Swift/BAT error region (296 arcsec), it is below the RASS limit and shows only moderate 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): 219.5964 = 14:38:23.15 Dec (J2000.0): +14.8912 = +14:53:28.2 Error: 3.1 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0180 [+0.0025, -0.0024] ct s^-1 Distance: 118 arcsec from Swift/BAT position. Flux: (5.29 [+0.72, -0.70])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Four uncatalogued sources were also detected too far from the GRB position to be likely afterglow candidates. 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/00021823. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39750. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37765] Fermi trigger No 763862734: Global MASTER-Net observations report
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39749 SUBJECT: Fermi trigger No 763862734: Global MASTER-Net observations report DATE: 25/03/17 00:16:11 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB250317.00 (trigger No 763862734,09h 52m 57.60s , -25d 26m 24.0s, R=6.3) errorbox 117 sec after notice time and 142 sec after trigger time at 2025-03-17 00:07:52 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 34 deg. The sun altitude is -17.2 deg. The galactic latitude b = 22 deg., longitude l = 260 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2814070 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 147 | 2025-03-17 00:07:52 | MASTER-OAFA | (09h 45m 18.11s , -26d 39m 32.4s) | C | 10 | 17.1 | 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/39749. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37764] GRB 250317A: Fermi GBM Final Real-time Localization
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39748 SUBJECT: GRB 250317A: Fermi GBM Final Real-time Localization DATE: 25/03/17 00:16:07 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 00:05:29 UT on 17 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250317A (trigger 763862734.52183 / 250317004). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 148.2, Dec = -25.4 (J2000 degrees, equivalent to J2000 09h 52m, -25d 23'), with a statistical uncertainty of 6.3 degrees. The angle from the Fermi LAT boresight is 23.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250317004/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250317004/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250317004/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39748. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37763] Fermi GRB 250316A: Global MASTER-Net observations report
by GCN Circulars 16 Mar '25

16 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39747 SUBJECT: Fermi GRB 250316A: Global MASTER-Net observations report DATE: 25/03/16 19:32:26 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 250316A ( Fermi GBM team, GCN 39741) errorbox 36240 sec after notice time and 36276 sec after trigger time at 2025-03-16 19:04:34 UT, with upper limit up to 17.3 mag. The observations began at zenith distance = 55 deg. The sun altitude is -38.8 deg. The galactic latitude b = 75 deg., longitude l = 24 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2813565 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 36307 | 2025-03-16 19:04:34 | MASTER-Kislovodsk | (13h 45m 52.80s , +24d 09m 52.7s) | C | 60 | 16.2 | 36387 | 2025-03-16 19:05:54 | MASTER-Kislovodsk | (13h 54m 40.28s , +24d 10m 54.0s) | C | 60 | 16.5 | 36527 | 2025-03-16 19:08:14 | MASTER-Kislovodsk | (13h 41m 50.76s , +26d 03m 19.9s) | C | 60 | 17.3 | 36609 | 2025-03-16 19:09:36 | MASTER-Kislovodsk | (13h 50m 50.40s , +26d 03m 08.2s) | C | 60 | 17.0 | 36689 | 2025-03-16 19:10:56 | MASTER-Kislovodsk | (13h 58m 47.69s , +26d 02m 55.6s) | C | 60 | 17.1 | 36769 | 2025-03-16 19:12:16 | MASTER-Kislovodsk | (14h 07m 45.91s , +26d 04m 05.9s) | C | 60 | 16.8 | 36849 | 2025-03-16 19:13:36 | MASTER-Kislovodsk | (14h 02m 29.99s , +24d 10m 37.1s) | C | 60 | 16.8 | 36928 | 2025-03-16 19:14:55 | MASTER-Kislovodsk | (14h 11m 21.21s , +24d 09m 17.3s) | C | 60 | 16.4 | 37235 | 2025-03-16 19:20:02 | MASTER-Kislovodsk | (13h 45m 55.17s , +24d 10m 08.5s) | C | 60 | 16.9 | 37315 | 2025-03-16 19:21:22 | MASTER-Kislovodsk | (13h 54m 37.47s , +24d 11m 22.2s) | C | 60 | 16.8 | 37394 | 2025-03-16 19:22:41 | MASTER-Kislovodsk | (13h 41m 51.58s , +26d 04m 40.2s) | C | 60 | 17.0 | 37474 | 2025-03-16 19:24:01 | MASTER-Kislovodsk | (13h 50m 48.05s , +26d 05m 34.6s) | C | 60 | 16.9 | 37553 | 2025-03-16 19:25:21 | MASTER-Kislovodsk | (13h 58m 42.08s , +26d 04m 34.8s) | C | 60 | 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/39747. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37762] GRB 250314A: SVOM/GRM analysis
by GCN Circulars 16 Mar '25

16 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39746 SUBJECT: GRB 250314A: SVOM/GRM analysis DATE: 25/03/16 18:36:43 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia (IRAP), Frédéric Piron (LUPM) Report on behalf of the SVOM team: With the event-by-event data downloaded through the X-band ground station, we conducted the standard analysis pipeline of the high redshift burst, GRB 250314A (Wang et al., GCN #39719). The GRM light curve shows that this burst consists of a single main episode with a T90 of 7.0 +3.6/-3.7 s in the 15-5000 keV band, which is consistent with the result from VHF data. The GRM on-ground localization of this burst is consistent with ECLAIRs (Wang et al., GCN #39719). With the localization of ECLAIRs (RA=201.272, DEC=-5.293), the time-averaged spectrum from T0-1 to T0+9 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.75 +0.19/-0.46 and the cutoff energy, parameterized as Epeak, is 43 +26/-19 keV. The event fluence (10-1000 keV) in this time interval is (3.1 +0.5/-0.8)E-07 erg/cm^2. With the measured redshift z=7.3 (D. B. Malesani et al., GCN 39732), we calculate the isotropic energy Eiso is about 4.6E52 erg. Thus GRB 250314A is well consistent with Type II GRBs in the 'Amati' relation diagram, as shown at: https://www.bursthub.cn//admin/static/grb250314A_amati.png We note that the calibration of SVOM/GRM is undergoing thus these results are preliminary. Refined analysis will be reported later. 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/39746. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37761] GRB 250316A: Swift ToO observations
by GCN Circulars 16 Mar '25

16 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39745 SUBJECT: GRB 250316A: Swift ToO observations DATE: 25/03/16 14:58:29 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 Swift/BAT GRB 250316A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021823 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 Swift/BAT 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/39745. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37760] GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
by GCN Circulars 16 Mar '25

16 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39744 SUBJECT: GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst DATE: 25/03/16 14:47:14 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250316A onboard (T0: 2025-03-16T08:59:57.690 UTC, Fermi GCN 39741). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst in a 16.384 s analysis time bin starting at T0 + 8.192 s with a sqrt(TS) of 17.7. An arcminute localization is found with DeltaLLHOut of 72.75 and a DeltaLLHPeak of 42.6. See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. The BAT position is RA, Dec = 219.63, 14.886 deg which is RA(J2000) = 14h 38m 31.20s Dec(J2000) = 14d 53’ 09.60″ with an estimated uncertainty of 5 arcmin radius. XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars. More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=763808432 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39744. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37759] GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
by GCN Circulars 16 Mar '25

16 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39743 SUBJECT: GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27 DATE: 25/03/16 10:32:24 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> N. A. Rakotondrainibe (LAM), A. de Ugarte Postigo (LAM), L. Izzo (INAF/OACN), D. B. Malesani (DAWN/NBI and Radboud), J. F. Agui Fernandez (CAHA), J. P. U. Fynbo (DAWN/NBI), S. Geier (GTC), G. Lombardi (GTC), A. Martin-Carrillo (UCD), N. R. Tanvir (Leicester), C. C. Thoene (AbAO), and G. Gomez Velarde (GTC) report on behalf of a larger collaboration: We observed the optical counterpart (Malesani et al., GCN 39727; see also Kennea et al., GCN 39734; Turpin et al., GCN 39739) of the SVOM/ECLAIRs GRB 250314A (Wang et al., GCN 39719), using the Gran Telescopio Canarias equipped with the OSIRIS+ camera. A sequence of 30 exposures of 30 s each (15 min in total) was secured in the z band, with mid time 2025 March 15.24 UT (16.8 hr after the GRB). In a preliminary reduction, no source is detected down to a 3-sigma limiting magnitude z > 24.4 (AB), calibrated against nearby stars from the Legacy Survey. Adding our z-band limit to the nearly simultaneous YJH photometry provided by VLT/HAWK-I (Malesani et al., GCN 39732) allows us to derive a more refined photometric redshift of z = 7.27 +0.14 -0.19 (1 sigma c.l.), assuming a power-law afterglow model with no dust extinction. The lack of optical detection is consistent with, and provides further evidence for, the high redshift of this GRB (Malesani et al., GCN 39732). View this GCN Circular online at https://gcn.nasa.gov/circulars/39743. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37758] The EP-WXT trigger 01709132801 is likely a flaring star
by GCN Circulars 16 Mar '25

16 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39742 SUBJECT: The EP-WXT trigger 01709132801 is likely a flaring star DATE: 25/03/16 09:55:17 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. Y. Li (NAOC, CAS), Q. C. Shui (IHEP, CAS), M. Q. Huang (UCST), Y. Liu (NAOC, CAS) report on behalf of the Einstein Probe team: The EP-WXT trigger (ID: 01709132801) on 2025-03-16T07:30:48.149 (UTC) is likely a stellar flare associated with the low mass star LP 368-98 or LP 368-99. The estimated flux of the flare is around 1.6 x 10^-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 2.0 x 10^31 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/39742. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37757] GRB 250316A: Fermi GBM Final Real-time Localization
by GCN Circulars 16 Mar '25

16 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39741 SUBJECT: GRB 250316A: Fermi GBM Final Real-time Localization DATE: 25/03/16 09:10:17 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 08:59:57 UT on 16 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250316A (trigger 763808402.691648 / 250316375). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 208.7, Dec = 24.2 (J2000 degrees, equivalent to J2000 13h 54m, 24d 11'), with a statistical uncertainty of 10.2 degrees. The angle from the Fermi LAT boresight is 94.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250316375/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250316375/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250316375/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39741. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37756] GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39740 SUBJECT: GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection DATE: 25/03/15 23:01:42 GMT FROM: mariaedvige.ravasio(a)ru.nl M. E. Ravasio (Radboud Univ.), E. Burns (LSU) and P.G. Jonker (Radboud Univ.) report on behalf of the Fermi-GBM Team: Fermi-GBM had full spatial and temporal coverage of the transient GRB 250315A/EP250315A detected by EP (Peng et al., GCN 39731; Sun et al. GCN 39738), with optical counterpart (Quirola-Vasquez et al. GCN 39733). There was no Fermi-GBM onboard trigger around the refined EP trigger time at T0=2025-03-15T05:58:16 (Sun et al. GCN 39738). The GBM Targeted Search [1], the most sensitive, coherent search for GRB-like signals was run in the time interval [-50;+500] s from the EP T0, seeking signals between 64 ms and 32.768 s in duration. A transient was significantly detected at T0+254 s on a 32 s timescale. The localization is consistent with the EP one, with a spatial association probability of 99%. The transient was best-fit with a "soft" spectrum (i.e., a Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7) for a GRB. [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/39740. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37755] GRB 250314A: EP-FXT afterglow detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39739 SUBJECT: GRB 250314A: EP-FXT afterglow detection DATE: 25/03/15 16:32:44 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> D. Turpin, B. Cordier (CEA), H. Q. Cheng, H. N. Yang (NAO, CAS), P. Y. Han (WHU), W. Yuan (NAO, CAS) Y. Wang (PMO, CAS), Rui-Zhi Li (YNAO, CAS) on behalf of the SVOM and Einstein Probe teams We performed a follow-up observation of GRB 250314A (Wang et al., GCN 39719) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation started at 2025-03-14 21:48:20 (T-TGRB ~ 8.9 hr) for about 1.1ks of exposure in total. A fading uncatalogued X-ray source is detected by both FXT-A and FXT-B at the position (J2000) RA, DEC = 201.3007, -5.2822 (error=10", 90% C.L.), 1.8 arcminute away from the SVOM/ECLAIRs position (Wang et al., GCN 39719). This position is consistent with the infrared afterglow candidate detected by the NOT and VLT/X-shooter (Malesani et al. GCN 39727; GCN 39732) and the Swift-XRT afterglow candidate source 1 (Kennea et al., GCN 39734). The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a Galactic hydrogen column density of 2.8 x 10^21 cm^-2 and a photon index of ~2.4. The derived average unabsorbed 0.5-10 keV flux is 5.2 (-/+1.6) x 10^(-13) erg/s/cm^2. Compared to the Swift-XRT epoch (Kennea et al., GCN 39734), the flux of the source 1 has shown a significant fading. We thus conclude this source is indeed the x-ray afterglow of GRB 250314A. Further observations of the GRB 250314A are planned with EP-FXT. The above observation was made with the EP-FXT instrument. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/39739. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37754] GRB 250314A: EP-FXT afterglow detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39739 SUBJECT: GRB 250314A: EP-FXT afterglow detection DATE: 25/03/15 16:32:44 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> D. Turpin, B. Cordier (CEA), H. Q. Cheng, H. N. Yang (NAO, CAS), P. Y. Han (WHU), W. Yuan (NAO, CAS) Y. Wang (PMO, CAS), Rui-Zhi Li (YNAO, CAS) on behalf of the SVOM and Einstein Probe teams We performed a follow-up observation of GRB 250314A (Wang et al., GCN 39719) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation started at 2025-03-14 21:48:20 (T-TGRB ~ 8.9 hr) for about 1.1ks of exposure in total. A fading uncatalogued X-ray source is detected by both FXT-A and FXT-B at the position (J2000) RA, DEC = 201.3007, -5.2822 (error=10", 90% C.L.), 1.8 arcminute away from the SVOM/ECLAIRs position (Wang et al., GCN 39719). This position is consistent with the infrared afterglow candidate detected by the NOT and VLT/X-shooter (Malesani et al. GCN 39727; GCN 39732) and the Swift-XRT afterglow candidate source 1 (Kennea et al., GCN 39734). The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a Galactic hydrogen column density of 2.8 x 10^21 cm^-2 and a photon index of ~2.4. The derived average unabsorbed 0.5-10 keV flux is 5.2 (-/+1.6) x 10^(-13) erg/s/cm^2. Compared to the Swift-XRT epoch (Kennea et al., GCN 39734), the flux of the source 1 has shown a significant fading. We thus conclude this source is indeed the x-ray afterglow of GRB 250314A. Further observations of the GRB 250314A are planned with EP-FXT. The above observation was made with the EP-FXT instrument. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/39739. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37753] EP250315a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39738 SUBJECT: EP250315a: refined analysis of the EP-WXT and EP-FXT observations DATE: 25/03/15 15:05:35 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> H.Sun (NAO, CAS), J. Q. Peng (IHEP, CAS), M. Q. Huang (USTC), W. X. Wang, W. D. Zhang (NAO, CAS) report on behalf of the Einstein Probe team: The X-ray transient EP250315a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Peng et al., GCN 39731). An optical counterpart candidate was detected by Gemini North (Quirola-Vasquez et al, GCN 39733). Refined analysis of the WXT data shows that the event started at T0=2025-03-15T05:58:16 (UTC) and lasted for about 280 s before the observation was disrupted by the autonomous follow-up observation. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a Galactic hydrogen column density of 2.97 x 10^20 cm^-2 and a photon index of 0.36 (-/+0.50). The derived average unabsorbed 0.5-4 keV flux is 5.4(-1.7, +2.2) x 10^(-10) erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP observed this source autonomously about 6 min after T0, starting at 2025-03-15T06:04:15 (UTC). Within the WXT error circle, on-ground analysis of the FXT data found an uncatalogued source at R.A. = 203.0287, DEC = -9.5301 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic), which is also consistent with the position of the optical counterpart candidate. The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a Galactic hydrogen column density of 2.97 x 10^20 cm^-2 and a photon index of 1.80(-/+0.05). The derived average unabsorbed 0.5-10 keV flux is 3.7(-/+0.17) x 10^(-11) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/39738. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37752] GRB 250314A: Swift/UVOT Upper Limits
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39737 SUBJECT: GRB 250314A: Swift/UVOT Upper Limits DATE: 25/03/15 14:40:53 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: Swift/UVOT observed the field of GRB250314A (Wange et al., GCN 39719) for a total of 1.6 ks in the U-band from 5.7 ks to 7.4 ks after the SVOM/ECLAIRs detection. We detect no optical/UV source at the position of the infrared (Malesani et al., GCN Circ 39727) and XRT (Kennea et al., GCN Circ. 39734) detections to an upper limit of u>20.94. This lack of detection would be consistent with the redshift reported by Malesani et al. (GCN Circ. 39732). XRT source #2 corresponds to a known optical source with a u-band magnitude of 16.99+-0.03. XRT source #3 is off the edge of the UVOT field. View this GCN Circular online at https://gcn.nasa.gov/circulars/39737. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37751] GRB 250312B: GRBAlpha detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39736 SUBJECT: GRB 250312B: GRBAlpha detection DATE: 25/03/15 14:36:05 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> M. Dafcikova, J. Ripa, M. Kolar (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, L. Szakszonova, 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 250312B (Fermi/GBM detection: GCN 39692; Swift/BAT-GUANO detection: GCN 39708) 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 2025-03-12 20:36:57.4 UTC. The T90 duration measured by GRBAlpha is 7.0 s and the overall significance during T90 reaches 10 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB250312B_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/39736. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37750] GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39735 SUBJECT: GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection DATE: 25/03/15 14:28:50 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> Ya.Kechin, V.Lipunov,N.Tyurina, E.Gorbovskoy, A.Kuznetsov, G.Antipov, D.Vlasenko,K.Zhirkov, P.Balanutsa, A.Chasovnikov, V.Topolev, V.Senik, K.Labzina (Lomonosov MSU), D.Buckley (SAAO), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A.Sosnovskij (Crao RAS), O.Gress, N.Budnev, O.Ershova (ISU), 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 AstrophysicsObservatory) MASTER Global Robotic Net (Lipunov, Kornilov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp, http://www.pereplet.ru/lipunov/625.html#625) started observation GRB 250313.89 (trigger 763594063, Ttrigger= 2025-03-13 21:27:38.85UT center (14h 43m 16.01s , -45d 40m 00.1s, radius=8.4167deg; https://master.sai.msu.ru/site/master2/event.php?id=2811407 ) at 2025-03-14 07:26:28 (OAFA, Argentina) and 2025-03-14 23:24:55 (SAAO, South Africa). Cover map is available at https://master3.sai.msu.ru:444/static/png/GRB250313.89/FERMI//1107805802.pn… MASTER OT J150644.86-414140.4 (AT 2025ehi) detection inside 1 sigma errobox. MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 15h 06m 44.86s -41d 41m 40.4s on 2025-03-14.20999 UT. The OT magnitude in 'Clear' filter is 16.0m (mlim = 18.9). The OT is seen in 38 images. We see the growing light curve of shine up to 13 zyading values within 1 day. There is no minor planet at this place. We have reference image on 2025-03-02.26325 UT with 'Clear' filter 19.9m. There is the Guide Star Catalog object 22 magnitude at same position. Spectral observations are required. View this GCN Circular online at https://gcn.nasa.gov/circulars/39735. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37749] GRB 250314A: Swift XRT Detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39734 SUBJECT: GRB 250314A: Swift XRT Detection DATE: 25/03/15 14:08:48 GMT FROM: Jamie Kennea at Penn State <jak51(a)psu.edu> J. A. Kennea (PSU), V. D'Elia (SSDC & INAF-OAR), P. A. Evans (Leicester) report on behalf of the Swift/XRT Team At 14:28UT on March 14, 2024 Swift began a Target-of-Opportunity observation of GRB 250314A, a SVOM ECLAIRs detected GRB (GCN #39719). Swift finds a uncatalogued point source inside the ECLAIRS error region at the following position: RA(J2000) = 201.30136, -5.2823: RA(J2000) = 13h 25m 12.22s, Dec(J2000) = -05h 16' 56.1'', with an estimated uncertainty of 3.5 arc-seconds radius (90% confidence). This position matches the reported optical counterpart (GCN #39727) with a reported redshift of z = 7.21 (GCN #39732). The XRT source has a peak flux of 2.2 x 10^-12 erg/s/cm^2 (0.3 - 10 keV). As Swift has performed only a single observation, we cannot confirm fading. We note also the presence of 2 other X-ray sources in the XRT field of view, source #2 lies at the edge of the ECLAIRs error region, source #3 lies outside. Given reported observations of source #1 and it's redshift, we do not believe these sources are credible afterglow candidates: Source no: 2 RA (J2000): 201.33727 [degrees] = 13h 25m 20.94s Dec (J2000): -5.16436 [degrees] = -05d 09' 51.7" Error: +4.8 [arcsec, 90% conf. radius] Flag: Good Source no: 3 RA (J2000): 201.44746 [degrees] = 13h 25m 47.39s Dec (J2000): -5.27117 [degrees] = -05d 16' 16.2" Error: +5.3 [arcsec, 90% conf. radius] Flag: Good View this GCN Circular online at https://gcn.nasa.gov/circulars/39734. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37748] EP250315a: optical counterpart candidate detected by Gemini North
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39733 SUBJECT: EP250315a: optical counterpart candidate detected by Gemini North DATE: 25/03/15 13:43:51 GMT FROM: Jonathan Quirola at Radboud University <jaquirola1990(a)gmail.com> J. A. Quirola-Vasquez (Radboud Univ.), P. G. Jonker (Radboud Univ.), D. B. Malesani (DAWN/NBI & Radboud Univ.), J. van Dalen (Radboud Univ.), A. Martin-Carrillo (UCD), A. J. Levan (Radboud Univ. & Warwick Univ.), A. van Hoof (Radboud Univ.), J. Sanchez-Sierras (Radboud Univ.), F. E. Bauer (PUC), M. E. Ravasio (Radboud Univ.), J. Chacon (PUC) report on behalf of a larger collaboration: We observed the field of EP250315a (Peng et al., GCN 39731), using the GMOS-N instrument mounted on the Gemini North Telescope. We obtained 3 x 40 s frames in the r band at a median time of 3.72 hr after the EP trigger. When compared to the Legacy Survey archive, we find an uncatalogued optical transient (OT) which is detected in the stacked image within the EP/FXT error circle (Peng et al., GCN 39731) at coordinates R.A. (J2000) = 13:32:06.98 Dec. (J2000) = -09:31:49.0 with an uncertainty of ~0.3 arcsec. The OT has a magnitude r = 21.72+-0.10 AB mag, calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction. We thus conclude the OT is very likely the optical counterpart of EP250315a. We acknowledge excellent support of the Gemini staff, especially Emanuele Farina. View this GCN Circular online at https://gcn.nasa.gov/circulars/39733. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37747] GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39732 SUBJECT: GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3 DATE: 25/03/15 12:45:58 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> D. B. Malesani (DAWN/NBI and Radboud), G. Pugliese (API-UvA), J. P. U. Fynbo (DAWN/NBI), B. Schneider (LAM), V. D’Elia (SSDC and INAF-OAR), A. de Ugarte Postigo (LAM), L. Izzo (INAF-OACn and DARK/NBI), P. G. Jonker (Radboud), A. J. Levan (Radboud and Warwick), J. T. Palmerio (CEA/Irfu), N. A. Rakotondrainibe (LAM), A. Saccardi (CEA/Irfu), N. R. Tanvir (U. Leicester), A. L. Thakur (INAF-IAPS), S. D. Vergani (CNRS, Obs. Paris/LUX), D. Xu (NAOC), Z.P. Zhu (NAOC) report on behalf of the Stargate collaboration: We observed the near-infrared candidate counterpart (Malesani et al., GCN 39727) of the long SVOM/ECLAIRs GRB 250314A (Wang et al., GCN 39719) at the ESO VLT, using the HAWK-I near-infrared imager (on UT4, Kueyen) and the X-shooter spectrograph (on UT3, Melipal). The object is well detected in the Y, J and H filters. HAWK-I observations started on 2025 Mar 15 at 05:23:28 UT (about 16.5 hr after the GRB). We measure preliminary AB magnitudes: Y = 23.2 +/- 0.15 J = 22.4 +/- 0.1 H = 22.5 +/- 0.1 For the spectra, the observation mid time was 2025 Mar 15.26 UT (about 17.4 hr after the GRB). The data cover the wavelength range 3000-21,000 AA and consist of 4 exposures of 1200 s each. In a preliminary reduction of the spectra, a faint continuum is confidently detected all across the NIR arm (down to 10,300 AA). Tentative signal is also seen in the very red end of the VIS arm, with a drop around 10,090 AA. While the S/N is too low to confidently identify individual metal absorption features, the break in the VIS is consistent with the onset of the Lyman forest (with possible contribution from damped Lyman-alpha absorption in the GRB host galaxy). The implied redshift is z ~ 7.3. The HAWK-I photometry is consistent with a break, rather than with a generically red shape of the continuum, given the red Y-J vs blue J-H color, consistent with the Y filter being partly dropped out. Assuming a power law model (no dust extinction), a fit to the available photometry provides a redshift z = 7.21 +0.18 -0.38 (1 sigma c.l.), fully consistent with the spectroscopic value. We acknowledge expert support from the ESO staff in Paranal. View this GCN Circular online at https://gcn.nasa.gov/circulars/39732. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37746] EP250315a: Einstein Probe detection of an X-ray transient
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39731 SUBJECT: EP250315a: Einstein Probe detection of an X-ray transient DATE: 25/03/15 07:33:28 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. Q. Peng (IHEP,CAS), M. Q. Huang (USTC), H. Sun, W. X. Wang, W. D. Zhang (NAO,CAS) report on behalf of the Einstein Probe team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250315a. The transient triggered EP-WXT (ID: 01709132646) at 2025-03-15T06:02:47 (UTC). The WXT position of the source is R.A. = 203.020 deg, DEC = -9.531 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 203.0307 deg, DEC = -9.5316 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/39731. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37745] GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39730 SUBJECT: GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits DATE: 25/03/15 07:21:33 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), E. Klunko (ISTP), A. Novichonok (KIAM), I. Nikolenko (INASAN), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 250226A (The Fermi GBM team, GCN 39479; V.Lipunov et. al, GCN 39481; Jiang et. al, GCN 39482; An et. al, GCN 39486; Zhu et. al, GCN 39487; Magnani et. al, GCN 39488; Li et. al, GCN 39489; Li et. al, GCN 39492; Aryan et. al, GCN 39509; Zou et. al, GCN 39511; Jiang et. al, GCN 39513; Li et. al, GCN 39514; Junjie-Jin et. al, GCN 39515; Thakur et. al, GCN 39518; Poidevin et. al, GCN 39524; Pathak et. al, GCN 39530; Pankov et. al, GCN 39539; Pankov et. al, GCN 39540; Svinkin et. al, GCN 39542; Tanasan et. al, GCN 39554) in the Rb filter with 1-meter Zeiss-1000 telescope of the Koshka Observatory (INASAN), and in the R-filter with 1.5-meter AZT-33IK telescope of Sayan Solar Observatory (Mondy). The observations began on 2025-02-28 23:27:51 UT, i.e. ~2.75 days since trigger at Koshka. We do not detect the optical counterpart in the stacked images from both telescopes. The preliminary upper limits are as follows: Date UT start t-T0 Exp. Filter UL(3sigma) (mid, days) (s) 2025-02-28 23:27:51 2.75236 47*180 Rb 22.1 2025-03-01 20:06:19 3.60304 57*120 R 23.8 Ref. stars USNO-B1.0 RA Dec R2 14:57:12.82 +20:57:33.04 15.73 14:57:12.66 +21:00:25.03 15.74 14:56:52.84 +21:00:58.82 14.86 The photometry is based on nearby stars from the USNO-B1.0 catalog (see above) and has not been corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39730. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37744] SVOM/MXT upper limit on GRB 250314A
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39729 SUBJECT: SVOM/MXT upper limit on GRB 250314A DATE: 25/03/15 07:13:31 GMT FROM: Diego Gotz at CEA <diego.gotz(a)cea.fr> D. Götz (CEA), F. Robinet (IJCLab), H. Goto (CEA), C. Plasse (CEA), P. Maggi (ObAS), M. Moita (CEA), C. van Hove (IJCLab) on behalf of the MXT team report: The field of GRB 250310A (Wange et al. GCN 39719, Li et al. 39728) was observed by MXT promptly after the SVOM slew starting at 12:59:55 UT, i.e. 193 s after ECLAIRs trigger. The analysis conducted on board did not reveal any significant source in the field of view of the telescope. By analyzing the full available MXT data set, we do not detect any X-ray counterpart within the ECLAIRs error box, nor at the position of the possible J-band/X-ray afterglow (Malesani et al. GCN 39727), down to a 3 sigma upper limit of about 5.5e-11 ergs/cm^2/s in the 0.5-10 keV energy range. This upper limit likely favours a high-z scenario, rather than a nearby highly extinguished GRB. 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. MXT has been developed by CNES in collaboration with CEA, IJCLab, University of Leicester and MPE. View this GCN Circular online at https://gcn.nasa.gov/circulars/39729. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37743] GRB250314A: SVOM/VT upper limit
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39728 SUBJECT: GRB250314A: SVOM/VT upper limit DATE: 25/03/15 05:04:43 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H.L. Li (NAOC), R.-Z. Li (YNAO, CAS), Y. Wang (PMO, CAS), J.X. Cao, D.F. Kong (GXU), L.P. Xin, Y. L. Qiu, C. Wu, Z.H. Yao, Y.N. Ma, X.H. Han, J. Wang, W.J. Xie, Y. Xu, H.B. Cai, J.Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM team: SVOM performed an automatic slew on the burst triggered by SVOM/ECLAIRs (Wang et al., GCN 39719). SVOM/VT began observing the field automatically with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With X band downlinked data, no any credible candidates were found in our single or stacked images within the errorbox of Eclairs (Wang et al., GCN 39719) compared to DESI catalog, or at the position of NOT candidate (Malesani et al., GCN 39727) in J-band. The 3 sigma limits in AB magnitude were derived as follows: --------------------------------------------------------- (t-T0)_mid(hr) exptime(ks) Band upperlim (3sigma) 2.2 2.85 VT_R 23.3 2.2 3.30 VT_B 23.3 If the NOT candidate is confirmed as the counterpart of the burst, given the non-detection in the VT-B and VT-R stacked images at early phase, it is likey the high-z GRB candidate. More deeper photometries in near-inferred or spectroscopies of the source are encouraged to confirm the nature of the event. 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/39728. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37742] GRB 250314A: NOT near-infrared candidate counterpart
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39727 SUBJECT: GRB 250314A: NOT near-infrared candidate counterpart DATE: 25/03/15 04:30:21 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> D. B. Malesani (DAWN/NBI), G. Corcoran (UCD), L. Izzo (INAF/OAC and DARK/NBI), B. Schneider (LAM), J. Palmerio (CEA/Irfu), A. Henderson de la Fuente (NOT) report on behalf of a larger collaboration: We observed the field of the SVOM GRB 250314A (Wang et al., GCN 39719) using the Nordic Optical Telescope equipped with the NOTCam near-infrared camera. Observations were carried out in the J band, for a total exposure time of 18 min on source, at a mean epoch of March 15.0523 UT (12.3 hr after the trigger). A faint object is apparent at coordinates (J2000): RA = 13:25:12.16 Dec = -05:16:55.1 Calibrating against nearby 2MASS stars, we measure J = 20.85 +- 0.15 (Vega). Nothing is visible at this location in the Legacy Survey nor in the Vista Hemisphere Survey (VHS), down to limits r > 24.5 (AB) and J > 20 (Vega). The position of this object is consistent with a bright X-ray source visible in public observations carried out by the Neil Gehrels Swift Observatory X-ray telescope (XRT; target ID 19616, PI Kennea). We thus consider this source as a plausible NIR counterpart candidate of GRB 250314A, though detection of fading will be necessary to confirm this hypothesis. View this GCN Circular online at https://gcn.nasa.gov/circulars/39727. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37741] GRB 250313A: Fermi GBM Detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39726 SUBJECT: GRB 250313A: Fermi GBM Detection DATE: 25/03/15 02:17:47 GMT FROM: eliza.neights(a)gmail.com Eliza Neights (George Washington University, NASA Goddard Space Flight Center), M. Godwin (UAH), C. Meegan (UAH) and O.J. Roberts (USRA) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 14:34:33.69 UT on 13 March 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250313A (trigger 763569278/250313607), which was also detected by Fermi LAT (Di Lalla et al. 2025, GCN 39711), AstroSat CZTI (Dasgupta et al. 2025, GCN 39714), SVOM/GRM (Wang et al. 2025, GCN 39716), and Konus-Wind (Frederiks et al. 2025, GCN 39721). The Fermi GBM Final Position location is consistent with the Fermi LAT position. The angle from the Fermi LAT boresight is 4 degrees. The GBM light curve consists of two emission episodes, a bright pulse lasting 12 s after the trigger time and a dimmer pulse about 280 s later. The duration (T90) is about 295.2 s (50-300 keV). The time-averaged spectrum from T0-2.2 to T0+389.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.36 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 320 +/- 20 keV. The event fluence (10-1000 keV) in this time interval is (9.4 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.7 s in the 10-1000 keV band is 55.4 +/- 0.5 ph/s/cm^2. The spectrum is fit about equally well by a Band function with Epeak = 280 +/- 20 keV, alpha = -1.34 +/- 0.02, and beta = -2.23 +/- 0.13. 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/39726. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37740] GRB 250313A: CALET Gamma-Ray Burst Monitor detection
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39725 SUBJECT: GRB 250313A: CALET Gamma-Ray Burst Monitor detection DATE: 25/03/15 01:55:09 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> K. Yamaoka (Nagoya U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The CALET Gamma-ray Burst Monitor (CGBM) was triggered by GRB 250313A at 14:34:30.53 UTC on 13 March 2025, which is also detected by Fermi-GBM (Fermi-GBM team, GCN #39703), Fermi-LAT (Di Lalla et al., GCN #39711), AstroSat CZTI (Dasgupta et al., GCN #39714), SVOM/GRM (Wang et al, GCN #39716) and Konus-Wind (Frederiks et al., GCN #39721). (https://cgbm.calet.jp/cgbm_trigger/flight/1425911606/index.html). The burst signal was seen by all CGBM detectors. The burst light curve shows a multi-peaked structure that starts at T+3.1 sec, peaks at T+11.3 sec, and ends at T+17.4 sec. The T90 and T50 durations measured by the SGM data are 10.1 +/- 0.5 sec and 4.8 +/- 0.3 sec (40-1000 keV), respectively. The ground-processed light curve is available at https://cgbm.calet.jp/cgbm_trigger/ground/1425911606/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University. View this GCN Circular online at https://gcn.nasa.gov/circulars/39725. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37739] GRB 250312B: Fermi GBM Observation
by GCN Circulars 15 Mar '25

15 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39724 SUBJECT: GRB 250312B: Fermi GBM Observation DATE: 25/03/15 00:56:42 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 20:36:56.64 UT on 12 March 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250312B (trigger 763504621/250312859), which was also localized by Swift/BAT-GUANO (J. DeLaunay et al. 2025, GCN 39708). The Fermi GBM on-ground location was given in GCN 39692 and it is consistent with the Swift/BAT-GUANO localization skymap. The angle from the Fermi LAT boresight is 105 degrees. The GBM light curve consists of single emission with two over lapping pulses, with a duration (T90) of about 5.4 s (50-300 keV). The time-averaged spectrum from T0-1.0 to T0+5.5 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.1 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 260 +/- 50 keV. The event fluence (10-1000 keV) in this time interval is (2.7 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.003 s in the 10-1000 keV band is 4.4 +/- 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/39724. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37738] GRB 250313A: Swift-XRT observations
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39723 SUBJECT: GRB 250313A: Swift-XRT observations DATE: 25/03/14 23:06:25 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M. A. Williams (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), 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 Fermi/LAT-detected burst GRB 250313A, collecting 6.3 ks of Photon Counting (PC) mode data between T0+30.7 ks and T0+82.7 ks. Seven 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 1: RA (J2000.0): 278.5986 = 18:34:23.66 Dec (J2000.0): +53.8117 = +53:48:42.1 Error: 5.7 arcsec (radius, 90% conf.) Count-rate: (3.20 [+1.07, -0.89])e-3 ct s^-1 Distance: 360 arcsec from Fermi/LAT position. Flux: (1.13 [+0.38, -0.32])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 278.4773 = 18:33:54.54 Dec (J2000.0): +53.6792 = +53:40:45.1 Error: 5.9 arcsec (radius, 90% conf.) Count-rate: (1.23 [+0.71, -0.54])e-3 ct s^-1 Distance: 184 arcsec from Fermi/LAT position. Flux: (5.1 [+2.9, -2.2])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 3: RA (J2000.0): 278.7435 = 18:34:58.45 Dec (J2000.0): +53.8112 = +53:48:40.2 Error: 6.1 arcsec (radius, 90% conf.) Count-rate: (1.19 [+0.90, -0.67])e-3 ct s^-1 Distance: 560 arcsec from Fermi/LAT position. Flux: (2.6 [+2.0, -1.5])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 278.7131 = 18:34:51.13 Dec (J2000.0): +53.8208 = +53:49:14.7 Error: 6.9 arcsec (radius, 90% conf.) Count-rate: (2.16 [+0.95, -0.76])e-3 ct s^-1 Distance: 532 arcsec from Fermi/LAT position. Flux: (2.38 [+1.04, -0.83])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 5: RA (J2000.0): 278.5290 = 18:34:6.96 Dec (J2000.0): +53.8678 = +53:52:04.2 Error: 8.1 arcsec (radius, 90% conf.) Count-rate: (1.57 [+0.84, -0.65])e-3 ct s^-1 Distance: 532 arcsec from Fermi/LAT position. Flux: (6.4 [+3.4, -2.6])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 6: RA (J2000.0): 278.5496 = 18:34:11.90 Dec (J2000.0): +53.7202 = +53:43:12.8 Error: 5.7 arcsec (radius, 90% conf.) Count-rate: (1.35 [+0.73, -0.55])e-3 ct s^-1 Distance: 41 arcsec from Fermi/LAT position. Flux: (8.6 [+4.7, -3.5])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 7: RA (J2000.0): 278.6648 = 18:34:39.55 Dec (J2000.0): +53.6612 = +53:39:40.2 Error: 7.4 arcsec (radius, 90% conf.) Count-rate: (7.5 [+6.0, -4.6])e-4 ct s^-1 Distance: 356 arcsec from Fermi/LAT position. 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/00021822. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39723. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37737] GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39722 SUBJECT: GRB250314A: SVOM/VT lack of bright optical candidate from VHF data DATE: 25/03/14 16:16:43 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> J. T. Palmerio (CEA), L.P. Xin (NAOC), S. D. Vergani (Obs. Paris), Y. Wang (PMO, CAS), Rui-Zhi Li (YNAO, CAS), Y. L. Qiu, H.L. Li., C. Wu, Z.H. Yao, Y.N. Ma, X.H. Han, H.B. Cai, J.Y. Wei (NAOC), Y. Canton, M. Garnichey, (Obs. Paris) report on behalf of the SVOM/VT team: After the trigger by SVOM/ECLAIRs at 2025-03-14T12:56:42 UTC (Tb), SVOM performed an automatic slew on the burst. SVOM/VT began observing the field at 2025-03-14T13:01:28, 285 seconds after the SVOM trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. From a preliminary analysis of the 1bit subimage and source list donwloaded via VHF, no credible candidate is identified down to VT_R~20. The subimage and source list cover ~55% of the ECLAIRs uncertainty region (Wang et al. GCN 39719). Further analysis will be performed once the full dataset is received via X-Band. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/39722. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37736] Konus-Wind detection of GRB 250313A
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39721 SUBJECT: Konus-Wind detection of GRB 250313A DATE: 25/03/14 16:07:45 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 250313A (Fermi-GBM detection: Fermi GBM team, GCN 39703; BALROG localization: Preis & Greiner, GCN 39704; Fermi-LAT detection: Di Lalla et al., GCN 39711; AstroSat CZTI detection: Dasgupta et al., GCN 39714; SVOM/GRM observation: Wang et al., GCN 39716) triggered Konus-Wind (KW) at T0=52473.618 s UT (14:34:33.618). The burst light curve shows a bright, multi-peaked emission pulse, with the duration of ~15 s, followed by a broad, weaker pulse, peaked at T0+270 s. The total duration of the burst is ~345 s. The emission is seen up to ~1.5 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250313_T52473/ As observed by Konus-Wind, the burst had a fluence of (1.06 ± 0.19)x10^-4 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 7.936 s, of (1.23 ± 0.10)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+345 s) is best fit in the 20 keV - 1.5 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.13 (-0.04,+0.04), the high energy photon index beta = -2.64 (-0.73,+0.21), the peak energy Ep = 237 (-15,+18) keV, chi2 = 34/63 dof. The spectrum near the peak count rate (measured from T0+7.936 s to T0+8.960 s) is best fit in the 20 keV - 1.5 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.52 (-0.07,+0.08), the high energy photon index beta = -2.80 (-0.41,+0.25), the peak energy Ep = 294 (-20,+21) keV, chi2 = 34/51 dof. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/39721. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37735] Konus-Wind detection of GRB 250308A
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39720 SUBJECT: Konus-Wind detection of GRB 250308A DATE: 25/03/14 15:54:17 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 250308A (SVOM-GRM detection: Wang et al., GCNs 39632, 39636; IPN triangulation: Kozyrev et al., GCN 39653; CALET-GBM detection: Kawakubo et al., GCN 39663; Swift-BAT/GUANO detection: DeLaunay et al., GCN 39676) triggered Konus-Wind at T0=65194.997 s UT (18:06:34.997). The burst light curve shows a multipeaked structure which starts at ~T0-40 ms and has a total duration of ~0.4 s. The emission is seen up to ~5 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250308_T65194/ As observed by Konus-Wind, the burst had a fluence of 8.23(-0.52,+0.54)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-6 ms, of 5.24(-0.69,+0.70)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 5 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.41(-0.12,+0.13) and Ep = 1176(-109,+125) keV (chi2 = 60/52 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.9 (chi2 = 60/51 dof). 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/39720. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37734] GRB 250314A: SVOM detection of a burst
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39719 SUBJECT: GRB 250314A: SVOM detection of a burst DATE: 25/03/14 14:12:08 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Y. Wang (PMO, CAS), Rui-Zhi Li (YNAO, CAS), M. Brunet, H. Yang (IRAP), T.Maiolino (LUPM) on behalf of the SVOM mission team. SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250314A (SVOM burst-id sb25031405) starting at 2025-03-14T12:56:42 UTC (Tb). 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 Count rate Trigger (CRT), from which we received 1 alert. CRT provided the alert with the best signal-to-noise-ratio (SNR) of 9.18 in the 8-120 keV energy band over a time window of 10.2 seconds starting at Tb. The light curve shows a single main episode, lasting ~20 s in ECLAIRs (5-120 keV) and ~10 s in GRM (5-550 keV). The localization of the best alert is R.A., Dec 201.272, -5.293 degrees: RA (J2000) = 13h25m05.28s Dec (J2000) = -05d17m36.30s with a 90% C.L. radius of 8.62 arcmin (including systematic error of 2 arcmin added in quadrature). The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250314A.png SVOM slewed to the burst. MXT and VT began observing the field after the slew. The analysis of the recorded data will be published in a future circular. 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 Y. 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/39719. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37733] EP250311a/GRB 250311A: Correction to EP-WXT detection time
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39718 SUBJECT: EP250311a/GRB 250311A: Correction to EP-WXT detection time DATE: 25/03/14 08:43:16 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> X. Mao (NAO, CAS), Y. J. Zhang (THU), Y. L. Hua (PMO, CAS), Z. X. Ling (NAO, CAS) report on behalf of the Einstein Probe team: The detection time for the transient EP250311a/GRB 250311A reported in GCN 39664 is incorrect: the corrected EP-WXT detection time is 2025-03-11T01:55:13 (UTC). We apologize for the mistake and any inconvenience caused by this, and thank MAXI team for their suggestion of a reanalysis on the data. View this GCN Circular online at https://gcn.nasa.gov/circulars/39718. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37732] GRB 250313B: SVOM/GRM observation of a soft bright short burst
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39717 SUBJECT: GRB 250313B: SVOM/GRM observation of a soft bright short burst DATE: 25/03/14 07:37:23 GMT FROM: wenlongzhang2018(a)163.com SVOM/GRM team: Wen-Long Zhang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia (IRAP), Frédéric Piron (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 250313B (SVOM trigger reference: sb25031307) at 2025-03-13T17:52:11.1 (T0). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of single main pulse with a T90 of 0.45 +0.27/-0.15 s in the 15-2000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250313B.png ECLAIRs was not collecting data at the time of this burst. 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: Wen-Long Zhang (IHEP) (zhangwl(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/39717. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37731] GRB 250313A: SVOM/GRM observation of a bright long burst
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39716 SUBJECT: GRB 250313A: SVOM/GRM observation of a bright long burst DATE: 25/03/14 07:18:32 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Wen-Jun Tan, Yan-Qiu Zhang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Bertrand Cordier, Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia (IRAP), Frédéric Piron (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 250313A (SVOM trigger reference: sb25031306) at 2025-03-13T14:34:33.900 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #39703), AstroSat (A. Dasgupta et al., GCN #39714) and Fermi/LAT (N. Di Lalla et al., GCN #39711). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a main emission followed by a flare with a T90 of 310.8 +3.4/-6.6 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250313A.png ECLAIRs was not collecting data at the time of this burst. 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/39716. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37730] LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39715 SUBJECT: LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST DATE: 25/03/14 03:56:23 GMT FROM: gaosj(a)smail.nju.edu.cn Shi-Jie Gao (NJU), Xiang-Dong Li (NJU), Yi-Xuan Shao (NJU), Ping Zhou (NJU) and Pei Wang (NAOC) report: Following the detection of the binary compact object merger event S250206dm by the LIGO-Virgo-KAGRA Collaboration (GCN [39175](https://gcn.nasa.gov/circulars/39175)), the CHIME/FRB collaboration reported a fast radio burst, FRB 20250206A (GCN [39216](https://gcn.nasa.gov/circulars/39216)). The burst occurred less than one minute after S250206dm, with an estimated spatial coincidence probability of 0.1%. We conducted a follow-up observation using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) on 2025-02-27, starting at MJD 60733.130141 (convert to infinite frequency in TDB scale). The observation used the L-band (1.25 GHz, 500 MHz bandwidth) 19-beam receiver, with the central beam pointed at R.A. = 22:34:48.72, Decl. = +12:10:11.6. The total integration time was 4800 s. No radio pulsation was detected in either the central beam or the surrounding beams. The non-detection places an upper limit of ~10 mJy on millisecond-duration pulses. This work was made use of the data from FAST (Five-hundred-meter Aperture Spherical radio Telescope, https://cstr.cn/31116.02.FAST). FAST is a Chinese national mega-science facility, operated by National Astronomical Observatories, Chinese Academy of Sciences. View this GCN Circular online at https://gcn.nasa.gov/circulars/39715. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37729] GRB 250313A: AstroSat CZTI detection of a bright long burst
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39714 SUBJECT: GRB 250313A: AstroSat CZTI detection of a bright long burst DATE: 25/03/14 03:34:39 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> A. Dasgupta (BITS Pilani, Hyderabad), G. Waratkar (IITB), M. Tembhurnikar (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 250313A which was also detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 39703) and Fermi/LAT (Lalla et al., GCN Circ. 39711). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-03-13 14:34:39.0 UTC. The measured peak count rate associated with the burst is 1059 (+56, -49) counts/s above the background in the combined data of three quadrants (out of four), with a total of 6772 (+199, -209) counts. The local mean background count rate was 182 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 12 (+1, -1) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-03-13 14:34:42.3 UTC. The measured peak count rate is 2082 (+96, -75) counts/s above the background in the combined Veto data of all quadrants, with a total of 13178 (+422, -439) counts. The local mean background count rate was 1222 (+6, -7) counts/s. We measure a T90 of 10 (+1, -1) 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/39714. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37728] IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39713 SUBJECT: IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect DATE: 25/03/14 02:36:51 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> K. Labzina, K.Zhirkov, V.Lipunov, E.Gorbovskoy, A.Kuznetsov, G.Antipov, D.Vlasenko, A.Kuznetsov, N.Tyurina, P.Balanutsa, A.Chasovnikov, V.Topolev, Ya.Kechin, V.Senik (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.Sosnovskij (Crao RAS), 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 AstrophysicsObservatory) MASTER-OAFA robotic telescope (Global MASTER-Net: Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started IceCube-250309A (IC GCN#39631) alert error-box (trigger No 1288692,14h 03m 12.24s , -10d 26m 24.0s, R=0.51) 9 sec after notice time (109 sec after trigger time) at 2025-03-09 07:37:54 UT, with upper limit up to 21.3 mag. (Lipunov et al.GCN#39630) MASTER cover map: https://master.sai.msu.ru/site/master2/observ.php?id=2805613 We analyzed MASTER archive images since 2013 of possible sources, that can be related with this event. There is blazar J140105.33-091631.6 inside 3 sigma https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=… We detected its decay and brightening up to usual state after 10 hours of IC event trigger time. MASTER archive light curve from 2013 year is available at http://observ.pereplet.ru/IC/MASTER_IC250309A.jpg This, we report observation of an Zhirkov effect, discovered earlier (The Astrophysic Jornal Letters, 896, L19, 2020 https://ui.adsabs.harvard.edu/abs/2020ApJ...896L..19L/abstract ). View this GCN Circular online at https://gcn.nasa.gov/circulars/39713. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37727] Fermi trigger No 763581136: Global MASTER-Net observations report
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39712 SUBJECT: Fermi trigger No 763581136: Global MASTER-Net observations report DATE: 25/03/14 02:16:43 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-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 GRB250313.74 (trigger No 763581136,18h 42m 24.00s , +00d 58m 58.8s, R=6.27) errorbox 27520 sec after notice time and 27564 sec after trigger time at 2025-03-14 01:31:35 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 56 deg. The sun altitude is -21.3 deg. The galactic latitude b = 2 deg., longitude l = 33 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2811247 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 27594 | 2025-03-14 01:31:35 | MASTER-Kislovodsk | (18h 39m 04.76s , +01d 26m 30.2s) | C | 60 | 17.6 | 27993 | 2025-03-14 01:38:13 | MASTER-Kislovodsk | (18h 38m 47.91s , -00d 27m 18.2s) | C | 60 | 17.6 | 28073 | 2025-03-14 01:39:33 | MASTER-Kislovodsk | (18h 40m 24.11s , +03d 18m 32.2s) | C | 60 | 17.1 | 28152 | 2025-03-14 01:40:53 | MASTER-Kislovodsk | (18h 23m 49.44s , +01d 26m 56.6s) | C | 60 | 17.9 | 28232 | 2025-03-14 01:42:12 | MASTER-Kislovodsk | (18h 25m 16.69s , +03d 20m 34.7s) | C | 60 | 17.3 | 28312 | 2025-03-14 01:43:32 | MASTER-Kislovodsk | (18h 23m 35.70s , -00d 26m 52.0s) | C | 60 | 18.0 | 28391 | 2025-03-14 01:44:52 | MASTER-Kislovodsk | (18h 43m 03.83s , +05d 12m 24.2s) | C | 60 | 17.0 | 28471 | 2025-03-14 01:46:11 | MASTER-Kislovodsk | (18h 39m 53.31s , -02d 21m 38.9s) | C | 60 | 16.6 | 28551 | 2025-03-14 01:47:31 | MASTER-Kislovodsk | (18h 27m 53.45s , +05d 14m 26.6s) | C | 60 | 17.4 | 28630 | 2025-03-14 01:48:51 | MASTER-Kislovodsk | (18h 54m 10.70s , +01d 26m 14.1s) | C | 60 | 17.5 | 28710 | 2025-03-14 01:50:10 | MASTER-Kislovodsk | (18h 53m 58.89s , -00d 29m 39.5s) | C | 60 | 16.4 | 28791 | 2025-03-14 01:51:31 | MASTER-Kislovodsk | (18h 55m 40.16s , +03d 20m 06.9s) | C | 60 | 17.2 | 28870 | 2025-03-14 01:52:51 | MASTER-Kislovodsk | (18h 55m 09.08s , -02d 21m 42.2s) | C | 60 | 16.7 | 28950 | 2025-03-14 01:54:11 | MASTER-Kislovodsk | (18h 24m 37.00s , -02d 20m 34.3s) | C | 60 | 17.6 | 29030 | 2025-03-14 01:55:30 | MASTER-Kislovodsk | (18h 31m 39.50s , +07d 07m 00.6s) | C | 60 | 16.8 | 29110 | 2025-03-14 01:56:50 | MASTER-Kislovodsk | (18h 42m 08.14s , -04d 15m 24.0s) | C | 60 | 16.6 | 29269 | 2025-03-14 01:59:30 | MASTER-Kislovodsk | (18h 46m 57.68s , +07d 08m 43.9s) | 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/39712. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37726] GRB 250313A: Fermi-LAT detection
by GCN Circulars 14 Mar '25

14 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39711 SUBJECT: GRB 250313A: Fermi-LAT detection DATE: 25/03/14 00:13:09 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> N. Di Lalla (Stanford Univ.), R. Gupta (NASA GSFC), and M. Arimoto (Kanazawa Univ.) report on behalf of the Fermi-LAT Collaboration: On March 13, 2025, Fermi-LAT detected high-energy emission from GRB 250313A, which was also detected by Fermi-GBM (trigger 763569278 / 250313607, GCN 39703). The best LAT on-ground location is found to be: RA, Dec = 278.53, 53.72 (J2000) with an error radius of 0.23 deg (90 % containment, statistical error only). This was 1 deg from the LAT boresight at the time of the GBM trigger (T0 = 14:34:33.69 UT). The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 1200 s after the GBM trigger is (4.0 ± 0.9) E-6 ph/cm2/s. The estimated photon index above 100 MeV is 2.0 ± 0.2. The highest-energy photon is a 1.5 GeV event which is observed ~ 27 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Makoto Arimoto (arimoto(a)se.kanazawa-u.ac.jp). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/39711. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37725] GRB 250313A: Swift ToO observations
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39710 SUBJECT: GRB 250313A: Swift ToO observations DATE: 25/03/13 23:18:11 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 Fermi/LAT GRB 250313A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021822 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 Fermi/LAT 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/39710. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37724] EP250304a: Pan-STARRS r and i-band imaging and photometry
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39709 SUBJECT: EP250304a: Pan-STARRS r and i-band imaging and photometry DATE: 25/03/13 20:31:31 GMT FROM: James Gillanders at University of Oxford <jhgillanders.astro(a)gmail.com> J. H. Gillanders (Oxford), M. Huber, K. C. Chambers (IfA, Univ. Hawaii), S. J. Smartt, K. W. Smith, S. Srivastav (Oxford), M. Nicholl, D. Young, M. Fulton (QUB), T.-W. Chen (NCU, Taiwan) A. S. B. Schultz, T. de Boer, J. Fairlamb, G. Paek, C. C. Lin, T. Lowe, E. Magnier, P. Minguez, I. A. Smith, R. J. Wainscoat (IfA, Univ. Hawaii). We observed the field of EP250304a (Chen et al., GCN 39580), using the Pan-STARRS telescope system (Chambers et al., 2016, arXiv e-prints, 1612.05560) on MJD 60745.55 (2025-03-11 13:12 UTC), approximately ~7.5 days after the EP-WXT detection (Chen et al., GCN 39580). The Pan-STARRS system consists of two 1.8m telescope units located at the summit of Haleakala on the Hawaiian island of Maui, employing an SDSS-like filter system denoted as grizy, and a broad w-filter, which is a composite of the gri-filters. Our observation consisted of 2x300s exposures in both the r and i filters. The images were processed with the Pan-STARRS pipeline. After astrometric and photometric calibration, reference images were subtracted from the target stacked images in the i-band only (Magnier et al., 2020a, ApJS, 251, 3; Magnier et al., 2020b, ApJS, 251, 6; Waters et al., 2020, ApJS, 251, 4). At this declination (Dec = -42), we possess a proprietary i-band reference stack with a total exposure time of 1170s. We also possess an r-band reference stack, but this has just 90s total exposure time. From these difference images, we measure an i-band AB magnitude, i~21.4. Previously reported r/R-band magnitudes by Liu et al., (GCN 39583; R = 20.8 +/- 0.1 at 2.4 hours post-burst) and Saccardi et al., (GCN 39585; r = 20.97 +/- 0.03 at 5.7 hours post-burst) indicate that the optical transient has not faded substantially in the ~week since explosion. A faint source is visible in the r-band images, but with only a 90s reference stack we cannot determine if this corresponds to host or transient flux. View this GCN Circular online at https://gcn.nasa.gov/circulars/39709. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37723] GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39708 SUBJECT: GRB 250312B: Swift/BAT-GUANO localization skymap of a burst DATE: 25/03/13 19:55:40 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250312B onboard (T0: 2025-03-12T20:36:56.64 UTC, Fermi trig 763504621) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 12.4 in a 8.192 s analysis time bin, starting at T0 - 2.048 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 10,136 deg2 and the 50% credible area is 2,853 deg2. The integrated probability inside the coded field of view is 1%. The NITRATES skymap is consistent with the Fermi localization reported in the final position notice (GCN 39692). The combined Fermi/GBM+NITRATES 90% credible area is 1,014 deg2 and the 50% credible area is 223 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=763504651/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/763504651/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/763504651/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=763504651 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39708. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37722] EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39707 SUBJECT: EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope DATE: 25/03/13 19:38:57 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng, Thomas G. Brink, Alexei V. Filippenko (UCB), Andy Skemer, Naunet Leonhardes-Barboza, Jordan Forman, Mayra Gutierrez, Isabelle Jones, Ravjit Kaur, Petra Mengistu, Avi Patel, Anavi Uppal, Nicole Wolff, and Michele Woodland (UCSC), report on behalf of the KAIT GRB team: We observed the K-type star PM J23221-0301, the possible optical counterpart of an EP flare event (trigger ID 01709061302; Shui et al., GCN 37615), with the Kast spectrograph on the 3 m Shane telescope at Lick Observatory. Observations were performed on Sep. 27.164 UTC, about 2.79 hours after the trigger, covering the 5800-7400 Ang wavelength range. The spectrum shows a red continuum with narrow absorption lines consistent with a K-type star spectrum. In particular, there is a very strong H-alpha emission line in the spectrum. Another spectrum of PM J23221-0301 was taken the following night on Sep. 28.320, about 1.272 days after the trigger, covering the 3500-10,000 Ang wavelength range. The H-alpha emission line had nearly faded away compared to the previous spectrum. We therefore confirm this to be the flare star related to the EP flare event. In addition, a new spectrum of star 2MASS J18351416+2435115 was taken on Sep. 28.216. Compared with the spectrum taken 3 days earlier (Zheng et al., GCN 37618), the Balmer emission lines faded significantly, confirming this star to be the flare star related to the EP flare event (trigger ID 01709059262; Liu et al., GCN 37593, 37594). View this GCN Circular online at https://gcn.nasa.gov/circulars/39707. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37721] Fermi GRB 250313A: Global MASTER-Net observations report
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39706 SUBJECT: Fermi GRB 250313A: Global MASTER-Net observations report DATE: 25/03/13 19:01:16 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-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 250313A ( Fermi GBM team, GCN 39703) errorbox 6499 sec after notice time and 6531 sec after trigger time at 2025-03-13 16:23:25 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 64 deg. The sun altitude is -40.5 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250313A errorbox 13836 sec after notice time and 13867 sec after trigger time at 2025-03-13 18:25:41 UT, with upper limit up to 16.3 mag. The observations began at zenith distance = 79 deg. The sun altitude is -34.2 deg. The galactic latitude b = 25 deg., longitude l = 80 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2811112 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 6534 | 2025-03-13 16:23:25 | MASTER-Tunka | (18h 26m 19.46s , +51d 36m 23.5s) | C | 5 | 15.9 | 6539 | 2025-03-13 16:23:25 | MASTER-Tunka | (18h 26m 19.46s , +51d 36m 23.4s) | C | 15 | 16.6 | Coadd 6553 | 2025-03-13 16:23:43 | MASTER-Tunka | (18h 26m 25.64s , +51d 35m 22.8s) | C | 5 | 16.1 | 6570 | 2025-03-13 16:24:01 | MASTER-Tunka | (18h 26m 19.56s , +51d 34m 23.6s) | C | 5 | 16.1 | 6588 | 2025-03-13 16:24:18 | MASTER-Tunka | (18h 26m 25.38s , +51d 34m 41.3s) | C | 5 | 16.0 | 6593 | 2025-03-13 16:24:18 | MASTER-Tunka | (18h 26m 25.37s , +51d 34m 41.2s) | C | 15 | 16.7 | Coadd 6607 | 2025-03-13 16:24:37 | MASTER-Tunka | (18h 26m 22.64s , +51d 36m 18.7s) | C | 5 | 16.1 | 6624 | 2025-03-13 16:24:54 | MASTER-Tunka | (18h 26m 22.61s , +51d 34m 53.1s) | C | 5 | 16.0 | 6645 | 2025-03-13 16:25:14 | MASTER-Tunka | (18h 26m 24.91s , +51d 36m 10.2s) | C | 10 | 16.4 | 6655 | 2025-03-13 16:25:14 | MASTER-Tunka | (18h 26m 24.93s , +51d 36m 10.4s) | C | 30 | 16.9 | Coadd 6669 | 2025-03-13 16:25:37 | MASTER-Tunka | (18h 26m 20.02s , +51d 35m 25.5s) | C | 10 | 16.3 | 6693 | 2025-03-13 16:26:02 | MASTER-Tunka | (18h 26m 19.41s , +51d 36m 26.4s) | C | 10 | 16.4 | 6718 | 2025-03-13 16:26:26 | MASTER-Tunka | (18h 26m 25.99s , +51d 35m 26.4s) | C | 10 | 16.4 | 6728 | 2025-03-13 16:26:26 | MASTER-Tunka | (18h 26m 26.01s , +51d 35m 25.7s) | C | 30 | 17.0 | Coadd 6742 | 2025-03-13 16:26:50 | MASTER-Tunka | (18h 26m 21.05s , +51d 34m 26.9s) | C | 10 | 16.5 | 6763 | 2025-03-13 16:27:12 | MASTER-Tunka | (18h 26m 26.84s , +51d 34m 44.6s) | C | 10 | 16.5 | 6786 | 2025-03-13 16:27:34 | MASTER-Tunka | (18h 26m 23.48s , +51d 36m 23.8s) | C | 10 | 16.5 | 6796 | 2025-03-13 16:27:34 | MASTER-Tunka | (18h 26m 23.48s , +51d 36m 23.5s) | C | 30 | 17.1 | Coadd 6809 | 2025-03-13 16:27:57 | MASTER-Tunka | (18h 26m 23.42s , +51d 34m 40.4s) | C | 10 | 16.5 | 6834 | 2025-03-13 16:28:22 | MASTER-Tunka | (18h 26m 26.91s , +51d 36m 01.6s) | C | 10 | 16.5 | 8874 | 2025-03-13 17:02:22 | MASTER-Tunka | (18h 26m 31.04s , +51d 36m 22.5s) | C | 10 | 16.9 | 8884 | 2025-03-13 17:02:22 | MASTER-Tunka | (18h 26m 31.07s , +51d 36m 23.1s) | C | 30 | 17.5 | Coadd 8919 | 2025-03-13 17:02:22 | MASTER-Tunka | (18h 26m 31.07s , +51d 36m 22.8s) | C | 100 | 18.2 | Coadd 9009 | 2025-03-13 17:02:22 | MASTER-Tunka | (18h 26m 31.05s , +51d 36m 22.9s) | C | 280 | 18.9 | Coadd 9139 | 2025-03-13 17:02:22 | MASTER-Tunka | (18h 26m 31.07s , +51d 36m 23.0s) | C | 540 | 19.2 | Coadd 8899 | 2025-03-13 17:02:47 | MASTER-Tunka | (18h 26m 29.42s , +51d 37m 23.3s) | C | 10 | 16.9 | 8922 | 2025-03-13 17:03:10 | MASTER-Tunka | (18h 26m 35.91s , +51d 36m 23.6s) | C | 10 | 16.9 | 8945 | 2025-03-13 17:03:33 | MASTER-Tunka | (18h 26m 30.59s , +51d 35m 24.2s) | C | 10 | 16.8 | 8955 | 2025-03-13 17:03:33 | MASTER-Tunka | (18h 26m 30.61s , +51d 35m 24.4s) | C | 30 | 17.5 | Coadd 8978 | 2025-03-13 17:04:07 | MASTER-Tunka | (18h 26m 36.90s , +51d 35m 42.9s) | C | 10 | 16.8 | 9010 | 2025-03-13 17:04:38 | MASTER-Tunka | (18h 26m 33.86s , +51d 37m 10.4s) | C | 10 | 16.9 | 9032 | 2025-03-13 17:05:00 | MASTER-Tunka | (18h 26m 33.89s , +51d 35m 44.0s) | C | 10 | 16.8 | 9042 | 2025-03-13 17:05:00 | MASTER-Tunka | (18h 26m 33.90s , +51d 35m 44.3s) | C | 30 | 17.6 | Coadd 9055 | 2025-03-13 17:05:23 | MASTER-Tunka | (18h 26m 37.63s , +51d 37m 14.3s) | C | 10 | 16.9 | 9091 | 2025-03-13 17:06:00 | MASTER-Tunka | (18h 26m 30.94s , +51d 36m 27.3s) | C | 10 | 16.9 | 9113 | 2025-03-13 17:06:21 | MASTER-Tunka | (18h 26m 31.10s , +51d 37m 28.0s) | C | 10 | 16.9 | 9123 | 2025-03-13 17:06:21 | MASTER-Tunka | (18h 26m 31.13s , +51d 37m 28.4s) | C | 30 | 17.5 | Coadd 9138 | 2025-03-13 17:06:46 | MASTER-Tunka | (18h 26m 37.27s , +51d 36m 28.0s) | C | 10 | 17.0 | 9161 | 2025-03-13 17:07:09 | MASTER-Tunka | (18h 26m 30.85s , +51d 35m 29.1s) | C | 10 | 16.9 | 9194 | 2025-03-13 17:07:42 | MASTER-Tunka | (18h 26m 36.43s , +51d 35m 41.8s) | C | 10 | 16.9 | 9204 | 2025-03-13 17:07:42 | MASTER-Tunka | (18h 26m 36.44s , +51d 35m 41.9s) | C | 30 | 17.6 | Coadd 9218 | 2025-03-13 17:08:06 | MASTER-Tunka | (18h 26m 34.84s , +51d 37m 14.2s) | C | 10 | 16.8 | 9240 | 2025-03-13 17:08:28 | MASTER-Tunka | (18h 26m 34.84s , +51d 35m 31.0s) | C | 10 | 16.8 | 9263 | 2025-03-13 17:08:51 | MASTER-Tunka | (18h 26m 37.58s , +51d 37m 22.7s) | C | 10 | 16.8 | 9273 | 2025-03-13 17:08:51 | MASTER-Tunka | (18h 26m 37.55s , +51d 37m 22.5s) | C | 30 | 17.5 | Coadd 9287 | 2025-03-13 17:09:15 | MASTER-Tunka | (18h 26m 31.18s , +51d 36m 32.0s) | C | 10 | 16.9 | 9309 | 2025-03-13 17:09:37 | MASTER-Tunka | (18h 26m 33.16s , +51d 37m 32.2s) | C | 10 | 16.8 | 9331 | 2025-03-13 17:09:59 | MASTER-Tunka | (18h 26m 38.97s , +51d 36m 31.6s) | C | 10 | 16.8 | 9341 | 2025-03-13 17:09:59 | MASTER-Tunka | (18h 26m 38.95s , +51d 36m 32.2s) | C | 30 | 17.4 | Coadd 9369 | 2025-03-13 17:10:38 | MASTER-Tunka | (18h 26m 32.93s , +51d 35m 33.1s) | C | 10 | 16.8 | 9393 | 2025-03-13 17:11:02 | MASTER-Tunka | (18h 26m 39.10s , +51d 35m 41.4s) | C | 10 | 16.8 | 9416 | 2025-03-13 17:11:25 | MASTER-Tunka | (18h 26m 35.66s , +51d 37m 29.0s) | C | 10 | 16.9 | 9426 | 2025-03-13 17:11:25 | MASTER-Tunka | (18h 26m 35.67s , +51d 37m 29.1s) | C | 30 | 17.6 | Coadd 9439 | 2025-03-13 17:11:47 | MASTER-Tunka | (18h 26m 35.80s , +51d 35m 40.3s) | C | 10 | 16.8 | 9461 | 2025-03-13 17:12:09 | MASTER-Tunka | (18h 26m 38.43s , +51d 37m 27.2s) | C | 10 | 16.8 | 9485 | 2025-03-13 17:12:34 | MASTER-Tunka | (18h 26m 32.01s , +51d 36m 36.8s) | C | 10 | 16.9 | 9495 | 2025-03-13 17:12:34 | MASTER-Tunka | (18h 26m 31.99s , +51d 36m 36.9s) | C | 30 | 17.6 | Coadd 9509 | 2025-03-13 17:12:57 | MASTER-Tunka | (18h 26m 33.59s , +51d 37m 37.5s) | C | 10 | 16.9 | 9532 | 2025-03-13 17:13:20 | MASTER-Tunka | (18h 26m 38.97s , +51d 36m 37.6s) | C | 10 | 16.9 | 9558 | 2025-03-13 17:13:46 | MASTER-Tunka | (18h 26m 32.63s , +51d 35m 37.9s) | C | 10 | 16.8 | 9568 | 2025-03-13 17:13:46 | MASTER-Tunka | (18h 26m 32.61s , +51d 35m 38.5s) | C | 30 | 17.6 | Coadd 9587 | 2025-03-13 17:14:15 | MASTER-Tunka | (18h 26m 39.27s , +51d 35m 40.7s) | C | 10 | 16.9 | 9613 | 2025-03-13 17:14:41 | MASTER-Tunka | (18h 26m 36.53s , +51d 37m 18.0s) | C | 10 | 16.8 | 9637 | 2025-03-13 17:15:05 | MASTER-Tunka | (18h 26m 36.60s , +51d 36m 00.4s) | C | 10 | 16.7 | 9647 | 2025-03-13 17:15:05 | MASTER-Tunka | (18h 26m 36.62s , +51d 36m 00.8s) | C | 30 | 17.4 | Coadd 9660 | 2025-03-13 17:15:28 | MASTER-Tunka | (18h 26m 40.68s , +51d 37m 37.4s) | C | 10 | 16.6 | 9681 | 2025-03-13 17:15:50 | MASTER-Tunka | (18h 26m 33.64s , +51d 36m 41.2s) | C | 10 | 16.6 | 9705 | 2025-03-13 17:16:14 | MASTER-Tunka | (18h 26m 34.47s , +51d 37m 42.4s) | C | 10 | 16.7 | 9715 | 2025-03-13 17:16:14 | MASTER-Tunka | (18h 26m 34.48s , +51d 37m 42.4s) | C | 30 | 17.4 | Coadd 9730 | 2025-03-13 17:16:38 | MASTER-Tunka | (18h 26m 39.57s , +51d 36m 42.1s) | C | 10 | 16.8 | 9753 | 2025-03-13 17:17:01 | MASTER-Tunka | (18h 26m 33.48s , +51d 35m 43.6s) | C | 10 | 16.8 | 9783 | 2025-03-13 17:17:31 | MASTER-Tunka | (18h 26m 39.45s , +51d 35m 47.0s) | C | 10 | 16.7 | 9793 | 2025-03-13 17:17:31 | MASTER-Tunka | (18h 26m 39.39s , +51d 35m 48.8s) | C | 30 | 17.5 | Coadd 9805 | 2025-03-13 17:17:53 | MASTER-Tunka | (18h 26m 37.41s , +51d 37m 20.4s) | C | 10 | 16.8 | 9828 | 2025-03-13 17:18:16 | MASTER-Tunka | (18h 26m 37.46s , +51d 36m 02.4s) | C | 10 | 16.8 | 9855 | 2025-03-13 17:18:43 | MASTER-Tunka | (18h 26m 41.32s , +51d 37m 31.8s) | C | 10 | 16.8 | 9865 | 2025-03-13 17:18:43 | MASTER-Tunka | (18h 26m 41.29s , +51d 37m 33.2s) | C | 30 | 17.4 | Coadd 9877 | 2025-03-13 17:19:05 | MASTER-Tunka | (18h 26m 34.82s , +51d 36m 45.9s) | C | 10 | 16.8 | 9904 | 2025-03-13 17:19:32 | MASTER-Tunka | (18h 26m 33.93s , +51d 37m 47.4s) | C | 10 | 16.8 | 9928 | 2025-03-13 17:19:57 | MASTER-Tunka | (18h 26m 40.06s , +51d 36m 46.9s) | C | 10 | 16.9 | 9938 | 2025-03-13 17:19:57 | MASTER-Tunka | (18h 26m 40.07s , +51d 36m 47.3s) | C | 30 | 17.6 | Coadd 9952 | 2025-03-13 17:20:20 | MASTER-Tunka | (18h 26m 35.06s , +51d 35m 48.2s) | C | 10 | 16.9 | 9977 | 2025-03-13 17:20:45 | MASTER-Tunka | (18h 26m 41.26s , +51d 36m 10.4s) | C | 10 | 16.8 | 9999 | 2025-03-13 17:21:07 | MASTER-Tunka | (18h 26m 38.25s , +51d 37m 36.4s) | C | 10 | 16.8 | 10009 | 2025-03-13 17:21:07 | MASTER-Tunka | (18h 26m 38.23s , +51d 37m 36.5s) | C | 30 | 17.5 | Coadd 10021 | 2025-03-13 17:21:29 | MASTER-Tunka | (18h 26m 38.20s , +51d 36m 19.4s) | C | 10 | 16.9 | 10045 | 2025-03-13 17:21:53 | MASTER-Tunka | (18h 26m 41.29s , +51d 37m 25.1s) | C | 10 | 16.8 | 10068 | 2025-03-13 17:22:17 | MASTER-Tunka | (18h 26m 36.40s , +51d 36m 53.4s) | C | 10 | 16.9 | 10078 | 2025-03-13 17:22:17 | MASTER-Tunka | (18h 26m 36.34s , +51d 36m 52.3s) | C | 30 | 17.5 | Coadd 10091 | 2025-03-13 17:22:39 | MASTER-Tunka | (18h 26m 35.75s , +51d 37m 52.4s) | C | 10 | 16.7 | 10118 | 2025-03-13 17:23:06 | MASTER-Tunka | (18h 26m 42.28s , +51d 36m 52.8s) | C | 10 | 16.8 | 10140 | 2025-03-13 17:23:29 | MASTER-Tunka | (18h 26m 35.52s , +51d 35m 53.7s) | C | 10 | 16.8 | 10150 | 2025-03-13 17:23:29 | MASTER-Tunka | (18h 26m 35.53s , +51d 35m 53.4s) | C | 30 | 17.4 | Coadd 10166 | 2025-03-13 17:23:54 | MASTER-Tunka | (18h 26m 40.98s , +51d 36m 05.8s) | C | 10 | 16.8 | 10189 | 2025-03-13 17:24:17 | MASTER-Tunka | (18h 26m 38.98s , +51d 37m 47.3s) | C | 10 | 16.8 | 10211 | 2025-03-13 17:24:39 | MASTER-Tunka | (18h 26m 39.03s , +51d 36m 22.3s) | C | 10 | 16.8 | 10221 | 2025-03-13 17:24:39 | MASTER-Tunka | (18h 26m 39.04s , +51d 36m 22.5s) | C | 30 | 17.4 | Coadd 10235 | 2025-03-13 17:25:03 | MASTER-Tunka | (18h 26m 41.70s , +51d 37m 38.1s) | C | 10 | 16.8 | 10257 | 2025-03-13 17:25:26 | MASTER-Tunka | (18h 26m 36.78s , +51d 36m 56.0s) | C | 10 | 16.8 | 10281 | 2025-03-13 17:25:50 | MASTER-Tunka | (18h 26m 36.93s , +51d 37m 57.5s) | C | 10 | 16.8 | 10291 | 2025-03-13 17:25:50 | MASTER-Tunka | (18h 26m 36.94s , +51d 37m 57.5s) | C | 30 | 17.5 | Coadd 10305 | 2025-03-13 17:26:13 | MASTER-Tunka | (18h 26m 43.13s , +51d 36m 57.2s) | C | 10 | 16.8 | 10329 | 2025-03-13 17:26:38 | MASTER-Tunka | (18h 26m 37.01s , +51d 35m 58.4s) | C | 10 | 16.8 | 10352 | 2025-03-13 17:27:01 | MASTER-Tunka | (18h 26m 43.18s , +51d 36m 20.2s) | C | 10 | 16.8 | 10362 | 2025-03-13 17:27:01 | MASTER-Tunka | (18h 26m 43.20s , +51d 36m 19.9s) | C | 30 | 17.3 | Coadd 10374 | 2025-03-13 17:27:23 | MASTER-Tunka | (18h 26m 39.80s , +51d 37m 43.0s) | C | 10 | 16.8 | 10720 | 2025-03-13 17:33:08 | MASTER-Tunka | (18h 26m 36.56s , +51d 37m 55.9s) | C | 10 | 16.6 | 10744 | 2025-03-13 17:33:32 | MASTER-Tunka | (18h 26m 42.69s , +51d 36m 56.6s) | C | 10 | 16.8 | 10754 | 2025-03-13 17:33:32 | MASTER-Tunka | (18h 26m 42.69s , +51d 36m 56.5s) | C | 30 | 17.5 | Coadd 10767 | 2025-03-13 17:33:55 | MASTER-Tunka | (18h 26m 37.68s , +51d 35m 57.3s) | C | 10 | 16.8 | 10789 | 2025-03-13 17:34:18 | MASTER-Tunka | (18h 26m 44.21s , +51d 36m 18.9s) | C | 10 | 16.8 | 10815 | 2025-03-13 17:34:43 | MASTER-Tunka | (18h 26m 40.39s , +51d 37m 30.3s) | C | 10 | 16.9 | 10825 | 2025-03-13 17:34:43 | MASTER-Tunka | (18h 26m 40.44s , +51d 37m 30.2s) | C | 30 | 17.7 | Coadd 10839 | 2025-03-13 17:35:08 | MASTER-Tunka | (18h 26m 40.46s , +51d 36m 13.0s) | C | 10 | 16.8 | 10862 | 2025-03-13 17:35:30 | MASTER-Tunka | (18h 26m 43.41s , +51d 37m 50.3s) | C | 10 | 16.8 | 10885 | 2025-03-13 17:35:53 | MASTER-Tunka | (18h 26m 36.68s , +51d 37m 01.7s) | C | 10 | 16.9 | 10895 | 2025-03-13 17:35:53 | MASTER-Tunka | (18h 26m 36.66s , +51d 37m 02.1s) | C | 30 | 17.6 | Coadd 10907 | 2025-03-13 17:36:15 | MASTER-Tunka | (18h 26m 38.30s , +51d 38m 01.9s) | C | 10 | 16.9 | 10930 | 2025-03-13 17:36:38 | MASTER-Tunka | (18h 26m 43.27s , +51d 37m 02.6s) | C | 10 | 16.8 | 10953 | 2025-03-13 17:37:01 | MASTER-Tunka | (18h 26m 38.01s , +51d 36m 02.4s) | C | 10 | 16.8 | 10963 | 2025-03-13 17:37:01 | MASTER-Tunka | (18h 26m 38.00s , +51d 36m 03.5s) | C | 30 | 17.6 | Coadd 10976 | 2025-03-13 17:37:24 | MASTER-Tunka | (18h 26m 44.18s , +51d 36m 19.5s) | C | 10 | 16.9 | 11004 | 2025-03-13 17:37:52 | MASTER-Tunka | (18h 26m 41.15s , +51d 38m 04.5s) | C | 10 | 16.8 | 11029 | 2025-03-13 17:38:17 | MASTER-Tunka | (18h 26m 41.16s , +51d 36m 26.7s) | C | 10 | 16.8 | 11039 | 2025-03-13 17:38:17 | MASTER-Tunka | (18h 26m 41.14s , +51d 36m 27.1s) | C | 30 | 17.5 | Coadd 11058 | 2025-03-13 17:38:46 | MASTER-Tunka | (18h 26m 43.88s , +51d 37m 41.9s) | C | 10 | 16.7 | 11205 | 2025-03-13 17:41:14 | MASTER-Tunka | (18h 26m 39.08s , +51d 38m 10.5s) | C | 10 | 16.8 | 11228 | 2025-03-13 17:41:37 | MASTER-Tunka | (18h 26m 44.83s , +51d 37m 10.1s) | C | 10 | 16.8 | 11238 | 2025-03-13 17:41:37 | MASTER-Tunka | (18h 26m 44.80s , +51d 37m 10.9s) | C | 30 | 17.3 | Coadd 11252 | 2025-03-13 17:42:01 | MASTER-Tunka | (18h 26m 39.48s , +51d 36m 12.1s) | C | 10 | 16.8 | 11275 | 2025-03-13 17:42:23 | MASTER-Tunka | (18h 26m 45.26s , +51d 36m 28.7s) | C | 10 | 16.5 | 11299 | 2025-03-13 17:42:47 | MASTER-Tunka | (18h 26m 42.16s , +51d 37m 46.4s) | C | 10 | 16.4 | 11334 | 2025-03-13 17:42:47 | MASTER-Tunka | (18h 26m 42.17s , +51d 37m 46.8s) | C | 80 | 17.2 | Coadd 11323 | 2025-03-13 17:43:11 | MASTER-Tunka | (18h 26m 42.26s , +51d 36m 16.2s) | C | 10 | 16.4 | 12037 | 2025-03-13 17:55:05 | MASTER-Tunka | (18h 26m 44.68s , +51d 36m 59.9s) | C | 10 | 16.9 | 12047 | 2025-03-13 17:55:05 | MASTER-Tunka | (18h 26m 44.69s , +51d 36m 59.7s) | C | 30 | 17.5 | Coadd 12059 | 2025-03-13 17:55:28 | MASTER-Tunka | (18h 26m 48.04s , +51d 38m 17.8s) | C | 10 | 16.8 | 12086 | 2025-03-13 17:55:55 | MASTER-Tunka | (18h 26m 41.99s , +51d 37m 39.3s) | C | 10 | 16.8 | 12201 | 2025-03-13 17:57:25 | MASTER-Tunka | (18h 26m 42.92s , +51d 38m 41.9s) | C | 60 | 16.9 | 13085 | 2025-03-13 18:12:08 | MASTER-Tunka | (18h 26m 50.42s , +51d 38m 12.4s) | C | 60 | 17.1 | 13145 | 2025-03-13 18:12:08 | MASTER-Tunka | (18h 26m 50.39s , +51d 38m 13.0s) | C | 180 | 18.0 | Coadd 13866 | 2025-03-13 18:25:09 | MASTER-Tunka | (18h 26m 53.63s , +51d 38m 41.8s) | C | 60 | 17.3 | 13898 | 2025-03-13 18:25:41 | MASTER-Kislovodsk | (18h 10m 41.76s , +52d 27m 30.9s) | C | 60 | 15.9 | 13989 | 2025-03-13 18:27:12 | MASTER-Kislovodsk | (18h 23m 41.90s , +52d 26m 09.7s) | C | 60 | 15.9 | 14150 | 2025-03-13 18:29:53 | MASTER-Kislovodsk | (18h 22m 06.18s , +54d 19m 08.0s) | C | 60 | 15.5 | 14177 | 2025-03-13 18:30:20 | MASTER-Tunka | (18h 26m 51.05s , +51d 38m 00.9s) | C | 60 | 17.2 | 14489 | 2025-03-13 18:35:33 | MASTER-Tunka | (18h 26m 49.28s , +51d 40m 07.6s) | C | 60 | 17.4 | 14623 | 2025-03-13 18:37:46 | MASTER-Kislovodsk | (18h 10m 37.65s , +52d 27m 19.5s) | C | 60 | 15.8 | 14703 | 2025-03-13 18:39:06 | MASTER-Kislovodsk | (18h 23m 44.86s , +52d 27m 56.3s) | C | 60 | 15.7 | 14811 | 2025-03-13 18:40:54 | MASTER-Tunka | (18h 26m 56.06s , +51d 38m 22.4s) | C | 60 | 17.6 | 14863 | 2025-03-13 18:41:46 | MASTER-Kislovodsk | (18h 22m 08.17s , +54d 19m 55.4s) | C | 60 | 15.9 | 15022 | 2025-03-13 18:44:26 | MASTER-Kislovodsk | (18h 13m 52.92s , +50d 32m 34.5s) | C | 60 | 15.7 | 15102 | 2025-03-13 18:45:45 | MASTER-Kislovodsk | (18h 26m 30.58s , +50d 33m 17.4s) | C | 60 | 15.8 | 15262 | 2025-03-13 18:48:25 | MASTER-Kislovodsk | (18h 10m 39.41s , +52d 28m 11.9s) | C | 60 | 16.3 | 15342 | 2025-03-13 18:49:45 | MASTER-Kislovodsk | (18h 23m 53.56s , +52d 26m 49.5s) | C | 60 | 15.8 | 15501 | 2025-03-13 18:52:24 | MASTER-Kislovodsk | (18h 22m 15.90s , +54d 20m 16.1s) | C | 60 | 16.2 | 15660 | 2025-03-13 18:55:04 | MASTER-Kislovodsk | (18h 13m 54.34s , +50d 32m 38.8s) | C | 60 | 15.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39706. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37720] GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39705 SUBJECT: GRB 250309B: PRIME near-infrared upper limits in 2nd epoch DATE: 25/03/13 18:41:30 GMT FROM: O. Guiffreda at UMD <oriogui(a)umd.edu> O. Guiffreda (UMD), J. Durbak (UMD), E. Troja (U Rome), A. S. Kutyrev (NASA/GSFC), S. B. Cenko (NASA/GSFC) Following up the initial PRIME detection (GCN 39670), the transient field was observed a second time ~3.5 days after the initial Fermi GBM trigger (GCN 39635). At the position of the optical counterpart AT2025dws (Stein et al., GCN 39639), we no longer detect any uncatalogued sources in either J-band or H-band. Using nearby VISTA Hemispherical Survey (VHS) stars for preliminary calibration we derive limiting magnitudes of J <21.0 AB mag and H <20.9 AB mag, not corrected for galactic extinction. PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023, Durbak et al. 2024). We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39705. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37719] GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39704 SUBJECT: GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607) DATE: 25/03/13 16:04:30 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger at 14:34:33 on 13 March 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 274.6 deg Decl.(2000.0) = 45.3 deg The 1 sigma statistical error radius is 0.1 deg. We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB250313607/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB250313607/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB250313607/json View this GCN Circular online at https://gcn.nasa.gov/circulars/39704. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37718] GRB 250313A: Fermi GBM Final Real-time Localization
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39703 SUBJECT: GRB 250313A: Fermi GBM Final Real-time Localization DATE: 25/03/13 14:44:53 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 14:34:33 UT on 13 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250313A (trigger 763569278.689058 / 250313607). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 276.4, Dec = 51.8 (J2000 degrees, equivalent to J2000 18h 25m, 51d 47'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 4.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250313607/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250313607/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250313607/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39703. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37717] The EP-WXT trigger 01709132551 is not a real source
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39702 SUBJECT: The EP-WXT trigger 01709132551 is not a real source DATE: 25/03/13 13:25:41 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. W. Hu (NAO, CAS), Y. Wang (PMO, CAS), P. Y. Han (HUST), W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709132551 at the time of 2025-03-13T12:04:16, is not a real source. View this GCN Circular online at https://gcn.nasa.gov/circulars/39702. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37716] EP250304a: SVOM/VT optical observation
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39701 SUBJECT: EP250304a: SVOM/VT optical observation DATE: 25/03/13 08:06:28 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> R. C. Chen (NJU), L. Lan (NAOC), C. W. Wang, W. J. Tan (IHEP), L. P. Xin, Y. L. Qiu, H. L. Li, Z. H. Yao, Y. Xu, P. P. Zhang, W. J. Xie, J. Wang, X. H. Han, Y. J. Xiao, H. B. Cai, J. Y. Wei (NAOC), J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM mission team. SVOM/VT conducted ToO follow-up observations of the X-ray transient EP250304a (Chen et al., GCN 39580) at the location of Swift-XRT (Page et al., GCN 39584) and Swift/UVOT (Shilling et al., GCN 39587) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. The optical counterpart of EP250304a (Trigger ID: 01709132237, Chen et al., GCN 39580; Liu et al., GCN 39583; Saccardi et al., GCN 39585; Shilling et al., GCN 39587) was clearly detected in VT_R and VT_B images. The brightness in AB magnitude was estimated to be: Mid time UTC | Band | Magnitude | Magnitude error 2025-03-08T14:31:28.502 | VT_B | 21.59 | 0.07 2025-03-08T14:31:28.502 | VT_R | 21.60 | 0.10 2025-03-05T10:27:01.518 | VT_B | 21.35 | 0.06 2025-03-05T10:27:01.518 | VT_R | 21.59 | 0.10 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/39701. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37715] EP250311a/GRB 250311A: EP-FXT follow-up observation
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39700 SUBJECT: EP250311a/GRB 250311A: EP-FXT follow-up observation DATE: 25/03/13 07:52:04 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> X. Mao (NAO, CAS), Y. J. Zhang (THU), Y. L. Hua (PMO, CAS), Z. X. Ling (NAO, CAS) report on behalf of the Einstein Probe team: Following the detection of the fast X-ray transient EP250311a (Mao et al., GCN 39664), also detected as GRB 250311A by MAXI (Tatano et al., GCN 39660), we performed an observation with the Follow-up X-ray Telescope (FXT) on board Einstein Probe. The observation began at 2025-03-12T15:29:21 (UTC), about 38 hours after the EP-WXT detection, with an exposure time of 6048 seconds. Two uncatalogued sources were detected within the WXT error circle, at R.A., DEC = 224.7009, -2.8412 deg (J2000) and R.A., DEC = 224.7199, -2.8760 deg (J2000), respectively, with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). Both of the sources have the flux at the level of ~ 5e-14 erg/cm2/s in 0.5-10 keV. No previously known X-ray sources are found within the FXT error circle around the two sources. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/39700. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37714] ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39699 SUBJECT: ATCA detection of the radio counterpart of GRB 250309B-AT2025dws DATE: 25/03/13 07:30:45 GMT FROM: Tao An at SHAO, CAS <antao(a)shao.ac.cn> Tao An, Yuanqi Liu (SHAO, China), Jinjun Geng, Xuefeng Wu (PMO, China), Ailing Wang (IHEP, China) report on behalf of a large collaboration. We report the detection of a radio counterpart to GRB 250309B-AT2025dws (GCN 39629, 39637, 39639) with the Australia Telescope Compact Array (ATCA). We conducted ATCA observations at 5.5 and 9 GHz on UT14:00-20:59 March 10, 2025 (~T0+1 day) targeting both the optical counterpart position of GRB 250309B-AT2025dws (GCN 39639) and a reported possible neutrino event position XRT1 (GCN 39631, 39633). No significant radio emission was detected above our 5σ detection threshold at either position, with a 1σ sensitivity of approximately 30 μJy/beam. Subsequent ATCA observations on UT14:00-20:59 March 12, 2025 (~T0+3 days) revealed a clear detection of radio emission at the position of GRB 250309B-AT2025dws with 0.322 ± 0.009 mJy at 5.5 GHz. The detection of this relatively bright radio afterglow (comparable to some of the brighter GRB radio afterglows) provides an excellent opportunity for continued monitoring of the spectral and temporal evolution of the afterglow emission. We plan to continue monitoring this source with ATCA. We thank the Jamie Stevens for rapid response in scheduling these observations. We thank the CSIRO Space and Astronomy staff for supporting these observations. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO. View this GCN Circular online at https://gcn.nasa.gov/circulars/39699. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37713] EP250302a: Chandra X-ray Detection
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39698 SUBJECT: EP250302a: Chandra X-ray Detection DATE: 25/03/13 02:48:18 GMT FROM: Brendan O'Connor at Carnegie Mellon University <boconno2(a)andrew.cmu.edu> B. O'Connor (CMU), D. Pasham (MIT), J. Hare (Catholic/GSFC), report on behalf of a larger collaboration: We observed EP250302a (Dai et al., GCN 39556) with the Chandra X-ray Observatory through Director's Discretionary Time (PI: O'Connor) for ~20 ks starting on 2025-03-11 at 14:04:47 UT, corresponding to 8.9 d (observer frame) after the EP trigger. We detect a clear X-ray source at the position of the optical (Zhu et al., GCN 39550; Busmann et al., GCN 39551; Leonini et al., GCN 39553; Wu et al., GCN 39555; Xin et al., GCN 39558; Adami et al., GCN 39560; Yang et al., GCN 39561; Becerra et al., GCN 39562; Izzo et al., GCN 39564; Pankov et al., GCN 39565; Reguitti, GCN 39568; Komesh et al., GCN 39569; Shilling and Breeveld, GCN 39570; Aryan et al., GCN 39572; Moskvitin et. al, GCN 39576; Wu et. al, GCN 39578; Pankov et. al, GCN 39586; Gupta et. al, GCN 39593) and X-ray (Dai et al., GCN 39556; Page et al. GCN 39557) counterpart at: RA, DEC (J2000) = 11:18:03.6, +33:35:09.6 with an uncertainty of ~0.8". The source flux is consistent with the afterglow decay inferred from Swift/XRT. Further analysis is planned. We thank Pat Slane for rapidly approving our DDT request, and the entire staff of the Chandra X-ray Observatory, in particular Vinay Kashyap, for rapidly scheduling these fast observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39698. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37712] GRB 250312A: Swift-XRT refined Analysis
by GCN Circulars 13 Mar '25

13 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39697 SUBJECT: GRB 250312A: Swift-XRT refined Analysis DATE: 25/03/13 01:21:03 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> D.N. Burrows (PSU), M. A. Williams (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), S. Dichiara (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 8.3 ks of XRT data for GRB 250312A, from 385 s to 34.7 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=0.51 (+/-0.06). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.80 (+0.22, -0.21). The best-fitting absorption column is 1.3 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 1.8 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 3.9 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.3 (+0.7, -0.6) x 10^21 cm^-2 Galactic foreground: 1.8 x 10^20 cm^-2 Excess significance: 3.0 sigma Photon index: 1.80 (+0.22, -0.21) If the light curve continues to decay with a power-law decay index of 0.51, the count rate at T+24 hours will be 0.022 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.5 x 10^-13 (1.0 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/01294765. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39697. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37711] Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39696 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB DATE: 25/03/12 22:57:50 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> L. Scotton (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 763509110/250312911 at 21:51:45.47 UT on 12 March 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to SAA entry." View this GCN Circular online at https://gcn.nasa.gov/circulars/39696. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37710] Fermi trigger No 763509110: Global MASTER-Net observations report
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39695 SUBJECT: Fermi trigger No 763509110: Global MASTER-Net observations report DATE: 25/03/12 22:16:12 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 GRB250312.91 (trigger No 763509110,11h 20m 38.40s , +63d 14m 24.0s, R=3.19) errorbox 38 sec after notice time and 61 sec after trigger time at 2025-03-12 21:52:47 UT, with upper limit up to 17.3 mag. The observations began at zenith distance = 21 deg. The sun altitude is -49.4 deg. The galactic latitude b = 51 deg., longitude l = 139 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2810236 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 67 | 2025-03-12 21:52:47 | MASTER-Kislovodsk | (11h 35m 54.68s , +63d 26m 27.5s) | C | 10 | 16.0 | 82 | 2025-03-12 21:52:47 | MASTER-Kislovodsk | (11h 35m 54.60s , +63d 26m 28.4s) | C | 40 | 17.1 | Coadd 96 | 2025-03-12 21:53:16 | MASTER-Kislovodsk | (11h 35m 54.54s , +63d 26m 29.5s) | C | 10 | 16.0 | 132 | 2025-03-12 21:53:47 | MASTER-Kislovodsk | (11h 35m 54.37s , +63d 26m 30.6s) | C | 20 | 16.8 | 177 | 2025-03-12 21:54:27 | MASTER-Kislovodsk | (11h 20m 23.59s , +63d 23m 11.2s) | C | 30 | 17.1 | 232 | 2025-03-12 21:55:17 | MASTER-Kislovodsk | (11h 20m 23.31s , +63d 23m 12.5s) | C | 40 | 17.3 | 297 | 2025-03-12 21:56:17 | MASTER-Kislovodsk | (11h 20m 22.85s , +63d 23m 13.8s) | C | 50 | 17.3 | 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/39695. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37709] Fermi GRB 250312B: Global MASTER-Net observations report
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39694 SUBJECT: Fermi GRB 250312B: Global MASTER-Net observations report DATE: 25/03/12 22:15:40 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 250312B ( Fermi GBM team, GCN 39692) errorbox 1617 sec after notice time and 1650 sec after trigger time at 2025-03-12 21:04:27 UT, with upper limit up to 18.4 mag. The observations began at zenith distance = 25 deg. The sun altitude is -47.1 deg. The galactic latitude b = 11 deg., longitude l = 296 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2810182 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1681 | 2025-03-12 21:04:27 | MASTER-SAAO | (11h 29m 04.39s , -48d 18m 30.7s) | C | 60 | 18.2 | 3030 | 2025-03-12 21:26:57 | MASTER-SAAO | (11h 29m 01.89s , -48d 17m 08.7s) | C | 60 | 18.2 | 3110 | 2025-03-12 21:28:16 | MASTER-SAAO | (12h 02m 31.64s , -51d 04m 13.5s) | C | 60 | 18.0 | 3170 | 2025-03-12 21:28:16 | MASTER-SAAO | (12h 02m 31.64s , -51d 04m 13.5s) | C | 180 | 18.4 | Coadd 3189 | 2025-03-12 21:29:35 | MASTER-SAAO | (12h 02m 31.65s , -51d 04m 13.4s) | C | 60 | 17.9 | 3268 | 2025-03-12 21:30:54 | MASTER-SAAO | (12h 02m 31.60s , -51d 04m 13.0s) | C | 60 | 17.9 | 3347 | 2025-03-12 21:32:13 | MASTER-SAAO | (12h 02m 31.51s , -51d 04m 12.3s) | C | 60 | 17.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39694. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37708] GRB 250312A: Enhanced Swift-XRT position
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39693 SUBJECT: GRB 250312A: Enhanced Swift-XRT position DATE: 25/03/12 22:04:03 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 1241 s of XRT Photon Counting mode data and 2 UVOT images for GRB 250312A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 29.51954, -42.39605 which is equivalent to: RA (J2000): 01h 58m 4.69s Dec (J2000): -42d 23' 45.8" with an uncertainty of 2.4 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39693. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37707] GRB 250312B: Fermi GBM Final Localization
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39692 SUBJECT: GRB 250312B: Fermi GBM Final Localization DATE: 25/03/12 21:55:01 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> The Fermi GBM team reports the detection of a likely LONG GRB "At 20:36:56.64 UT on 12 March 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250312B (trigger 763504621/250312859). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 180.86, Dec = -50.96 (J2000 degrees, equivalent to J2000 12h 3m, -50d 57'), with a statistical uncertainty of 4.87 degrees. The angle from the Fermi LAT boresight is 105 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250312859/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250312859/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250312859/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/39692. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37706] LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39691 SUBJECT: LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO DATE: 25/03/12 20:51:58 GMT FROM: Maia Williams at PSU <mjw6837(a)psu.edu> Maia Williams (PSU), Samuele Ronchini (PSU), Gayathri Raman (PSU), James DeLaunay (PSU), Tyler Parsotan (NASA GSFC), Jamie A. Kennea (PSU), Aaron Tohuvavohu (Caltech) report: Swift/BAT was observing 97.58% of the GW localization probability ([bayestar.multiorder.fits](https://gracedb.ligo.org/api/superevents/S250304c…) at merger time. A fraction 43.22% of the GW localization posterior is contained inside the BAT coded FoV. The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; [Tohuvavohu et al. 2020, ApJ, 900, 1](https://iopscience.iop.org/article/10.3847/1538-4357/aba94f)). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. Using the NITRATES analysis ([DeLaunay + Tohuvavohu 2022, ApJ, 941, 169](https://iopscience.iop.org/article/10.3847/1538-4357/ac9d38)), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits. We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins. In units of 10^-7 erg/s/cm^2: |time_bin (s) |soft |normal|hard |GRB170817 |-|-|-|-|-| |0.256 |7.85 |5.54 |5.01 |6.09 |1.024 |3.99 |2.82 |2.55 |3.09 |4.096 |2.12 |1.50 |1.36 |1.65 |16.384 |1.29 |0.91 |0.82 |1.00 The upper limits as function of sky position are plotted here, alongside the GW localization: [https://zenodo.org/records/15008852] The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: [https://www.swift.psu.edu/guano/] View this GCN Circular online at https://gcn.nasa.gov/circulars/39691. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37705] GRB 250226B: Fermi GBM Observation
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39690 SUBJECT: GRB 250226B: Fermi GBM Observation DATE: 25/03/12 20:16:32 GMT FROM: Jacob Smith at Fermi-GBM Team <jrs0118(a)uah.edu> Jacob Smith (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: At 22:30:23.12 UT on 26 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250226B (trigger 762301828/250226938). which was also detected by INTEGRAL SPI-ACS (J. Rodi, et al. 2025, GCN 39519) and Swift/BAT-GUANO (S. Ronchini, et al., 2025, GCN 39673). The angle from the Fermi LAT boresight is 71 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 26 s (50-300 keV). The time-averaged spectrum from T0+0.003 to T0+27.457 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.09 +/- 0.03 and the cutoff energy, parameterized as Epeak, is 1688 +/- 250 keV. The event fluence (10-1000 keV) in this time interval is (1.60 +/- 0.03)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 9.7 +/- 0.2 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/39690. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37704] Swift GRB 250312A: Global MASTER-Net observations report
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39689 SUBJECT: Swift GRB 250312A: Global MASTER-Net observations report DATE: 25/03/12 18:04:11 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-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 Swift GRB 250312A ( A. Melandri et al., GCN 39686) errorbox 15966 sec after notice time and 16003 sec after trigger time at 2025-03-12 17:51:00 UT, with upper limit up to 18.2 mag. Observations started at twilight. The observations began at zenith distance = 54 deg. The sun altitude is -11.5 deg. The galactic latitude b = -69 deg., longitude l = 264 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2809737 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 16093 | MASTER-SAAO | C | 180 | 17.1 | 16292 | MASTER-SAAO | C | 180 | 18.2 | 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/39689. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37703] GRB 250302A: Fermi GBM Observation
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39688 SUBJECT: GRB 250302A: Fermi GBM Observation DATE: 25/03/12 17:18:02 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> M. Dafcikova (MUNI) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 13:46:32.99 UT on 02 March 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250302A (trigger 762615997/250302574). which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2025, GCN 39675). The Fermi GBM on-ground location is consistent with the Swift/BAT position. The angle from the Fermi LAT boresight is 67 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 56 s (50-300 keV). The time-averaged spectrum from T0-3.6 to T0+71.2 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.49 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 394 +/- 135 keV. The event fluence (10-1000 keV) in this time interval is (8.8 +/- 0.5)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+10 s in the 10-1000 keV band is 2.5 +/- 0.2 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak = 324 +/- 194 keV, alpha = -1.48 +/- 0.09 and beta = -2.0 +/- 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/39688. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37702] GRB 250309B/AT 2025dws: Daochen/RC-10 optical counterpart observation
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39687 SUBJECT: GRB 250309B/AT 2025dws: Daochen/RC-10 optical counterpart observation DATE: 25/03/12 17:01:44 GMT FROM: sqjiang at NAOC <sqjiang(a)bao.ac.cn> S.Q. Jiang (NAOC), S.H. Wang (THU), J. An, X. Liu, Z.P. Zhu, D. Xu (NAOC), S.Y. Fu (HUST), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the optical counterpart AT 2025dws (Stein et al., GCN 39639, 39644; Pérez-Fournon et al., GCN 39643; Moskvitin et al., GCN 39645, 39658; Perley et al., GCN 39646; Malesani et al., GCN 39647; Page and Evans, GCN 39649; Ducoin et al., GCN 39650; Shin et al., GCN 39654; Wang et al., GCN 39661; Guiffreda et al., GCN 39670) of GRB 250309B (GBM team, GCN 39635; Preis and Greiner, GCN 39629; McDermott et al., GCN 39642; Wang et al., GCN 39648; Kozyrev et al., GCN 39652; Frederiks et al., GCN 39655), using the 0.33 m diameter telescope RC-10 located at Daochen, Sichuan, China. Observations started at 18:53:25.836 on 2025-03-09, i.e., 11.247 hrs after the Fermi/GBM trigger time, a series of 600 s frames in sloan r-band were obtained. The optical transient was detected in our stacked image with mag_r= 19.7 +/- 0.2 at a median time of 12.260 hrs after the trigger time, calibrated with the nearby Pan-STARRS field and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39687. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37701] GRB 250312A: Swift detection of a burst
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39686 SUBJECT: GRB 250312A: Swift detection of a burst DATE: 25/03/12 13:41:19 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> A. Melandri (INAF-OAR), V. D'Elia (SSDC & INAF-OAR), J. J. DeLaunay (PSU), S. Dichiara (PSU), R. Gupta (NASA GSFC), J. A. Kennea (PSU), M. J. Moss (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 13:24:17 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250312A (trigger=1294765). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 29.510, -42.404 which is RA(J2000) = 01h 58m 02s Dec(J2000) = -42d 24' 15" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Only the first 8 seconds of the BAT light curve are immediately available. This limited data shows a complex peak structure that extends beyond the T+8s cut-off. The peak count rate was ~1800 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 13:26:33.0 UT, 135.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 29.51911, -42.39599 which is equivalent to: RA(J2000) = 01h 58m 04.59s Dec(J2000) = -42d 23' 45.6" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 37 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.79 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3 (+2.65/-2.31) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 7.29e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 427 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.017. Burst Advocate for this burst is A. Melandri (andrea.melandri AT inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/39686. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37700] GRB 241213A: VIRT Optical Upper Limit
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39685 SUBJECT: GRB 241213A: VIRT Optical Upper Limit DATE: 25/03/12 13:11:33 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), R. Querrard (UVI), and C. Watson (UVI) report: We observed the field of GRB241213A (Gupta et al., GCN 38547) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2024-12-14 starting at 7:34:05 UT (T-mid ~ T0 + 20.3 hrs). We performed a series of exposures in an R filter with a total exposure of 740s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.1. We do not detect any source within the enhanced XRT position (Osborne et al. GCN 38552). This non-detection is consistent with reported detections (Qiu et al., GCN 38566) and upper limits (Spiridonova et al., GCN 38550; Shilling et al., GCN 38564; Brivio et al., GCN 38553; Strausbaugh et al., GCN 38558; and Qiu et al., GCN 38566). We report the following 3-sigma upper limit: T_mid ||Exposure ||Filter ||Limit T+20.3 h || 740 s || R || > 20.3 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/39685. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37699] GRB 241228A: VIRT Optical Upper Limit
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39684 SUBJECT: GRB 241228A: VIRT Optical Upper Limit DATE: 25/03/12 13:10:18 GMT FROM: Priya Gokuldass at ERAU <gokuldap(a)my.erau.edu> R. Querrard (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), K. Smith (UVI), C. Watson (UVI) report: We observed the field of GRB241228A (D'Elia et al., GCN 38681) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2024-12-28 starting at 03:57:15 UT (T-mid ~ T0 + 43.91 hrs). We performed a series of exposures in an R filter with a total exposure of 2060s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.68. We do not detect any source within the enhanced XRT position (Evans et al. GCN 38683). This non-detection is consistent with reported upper limits (Kuin et al., GCN 38685; Mohan et al., GCN 38689; Lipunov et al., GCN 38693; Zhu et al., GCN 38703; Volnova et al., GCN 38709; and Ror et al., GCN 38815). We report the following 3-sigma upper limit: T_mid ||Exposure ||Filter ||Limit T+43.91 h || 2060 s || R || > 20.4 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/39684. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37698] GRB 250311A/EP250311a: Optical upper limits with Kinder observations
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39683 SUBJECT: GRB 250311A/EP250311a: Optical upper limits with Kinder observations DATE: 25/03/12 13:01:59 GMT FROM: Janet Chen at National Central University <janetstars(a)gmail.com> A. Sankar. K, M.-H. Lee, A. Aryan, Y.-H. Lee, C.-H. Lai, T.-W. Chen, H.-Y. Hsiao, W.-J. Hou (all NCU), A. K. H. Kong (NTHU), J. Gillanders (Oxford), S. J. Smartt (Oxford/QUB), Y. J. Yang, C.-S. Lin, Y.-C. Pan, C.-C. Ngeow, H.-C. Lin, J.-K. Guo (all NCU), S. Yang, L. L. Fan, Z. N. Wang, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient GRB 250311A/EP250311a (Tatano et al., GCN 39660; Mao et al., GCN 39664) using the 40cm SLT and 1 meter LOT telescopes at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al. 2024, arXiv:2406.09270). The first SLT epoch of observations in the r band started at 15:28 UT on the 11th of March 2025 (MJD = 60745.6442), ~13.52 hrs after the EP trigger, while the first LOT epoch of observations in the r band started at 17:01 UT on the 11th of March 2025 (MJD = 60745.7090), ~ 15.08 hrs after the EP trigger. We utilised the astroalign (Beroiz et al., 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al., 2022, ApJ, 935, 167) packages to align and stack the individual frames. We did not detect any uncataloged optical counterpart candidate within the EP-WXT localization error circle of radius 2.8 arcminutes in the stacked image. Moreover, we employed the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform template subtraction utilizing the "sfft" (Hu, 2022, ApJ, 936, 157) algorithm using a template from SkyMapper DR4 (Onken et., 2024, PASA, 41, e061). We found no evidence of any prominent candidate optical counterpart in the difference image as well. We further employed the Python-based package AutoPhOT to perform PSF photometry on our stacked frames. The details of the observations and measured 3-sigma upper limits (in the AB system) were as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass SLT | r | 60745.6442 | 13.52 | 300 * 9 | >19.6 | 1".5 | 2.04 LOT | r | 60745.7090 | 15.08 | 300 * 6 | >21.2 | 1".3 | 1.36 The non-detection of any prominent optical counterpart is consistent with Li et al. (GCN 39667). The presented upper limits were calibrated using the field stars from the Pan-STARRS1 catalog and were not corrected for the expected Galactic foreground extinction corresponding to a reddening of A_r = 0.27 mag, respectively, in the direction of the transient (Schlafly & Finkbeiner 2011). View this GCN Circular online at https://gcn.nasa.gov/circulars/39683. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37697] GRB 250223B: Fermi GBM Observation
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39682 SUBJECT: GRB 250223B: Fermi GBM Observation DATE: 25/03/12 10:06:11 GMT FROM: Rushikesh Sonawane at IISER, TVM <rushikesh23(a)iisertvm.ac.in> R. Sonawane (IISER, TVM), R. Hamburg (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 10:19:23.76 UT on 23 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250223B (trigger 761998768/250223430). which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2025, GCN 39671). The Fermi GBM on-ground location is consistent with the Swift/BAT position. The angle from the Fermi LAT boresight is 56 degrees. The GBM light curve consist of multiple spikes with a duration (T90) of about 2.4 s (50-300 keV). The time-averaged spectrum from T0-1.0 to T0+1.7 s is best fit by a simple power law function with index -1.24 +/- 0.07. The event fluence (10-1000 keV) in this time interval is (3.9 +/- 0.6)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0+1.2 s in the 10-1000 keV band is 2.9 +/- 1.1 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/39682. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37696] GRB 250311A: Swift-XRT observations
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39681 SUBJECT: GRB 250311A: Swift-XRT observations DATE: 25/03/12 09:58:00 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.A. Kennea (PSU), D.N. Burrows (PSU), M. A. Williams (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 250311A/MAXI J1457-026 (GCN Circ. 39660) in a series of observations tiled on the sky. The total exposure time is 1.4 ks, distributed over 4 tiles; the maximum exposure at a single sky location in the tiling was 731 s. The data were collected between T0+34.4 ks and T0+36.0 ks, and are entirely in Photon Counting (PC) mode. Two 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 1: RA (J2000.0): 224.4476 = 14:57:47.43 Dec (J2000.0): -2.7859 = -02:47:09.2 Error: 9.8 arcsec (radius, 90% conf.) Count-rate: (9.8 [+6.3, -4.5])e-3 ct s^-1 Distance: 777 arcsec from MAXI position. Source 2: RA (J2000.0): 224.4381 = 14:57:45.15 Dec (J2000.0): -2.7813 = -02:46:52.7 Error: 8.7 arcsec (radius, 90% conf.) Count-rate: 0.0134 [+0.0074, -0.0055] ct s^-1 Distance: 744 arcsec from MAXI position. We note that these observations do not cover the localisation of X-ray transient EP250311a (GCN 39664), which may be associated with the same trigger. 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_GRB00135. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39681. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37695] GRB 250228A: Fermi GBM Observation
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39680 SUBJECT: GRB 250228A: Fermi GBM Observation DATE: 25/03/12 07:13:25 GMT FROM: Utkarsh Pathak at IIT Bombay <utkarshpathak.07(a)gmail.com> U. Pathak (IIT Bombay), M. Dafčíková (Masaryk U.), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 07:23:46.16 UT on 28 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250228A (trigger 762420231/250228308). which was also detected by Swift/BAT-GUANO (Ronchini et al. 2025, GCN 39674). The Fermi GBM on-ground location is consistent with the Swift/BAT position. The angle from the Fermi LAT boresight is 27 degrees. The GBM light curve consists of a weak pulse from a single emission episode with a duration (T90) of about 0.6 s (50-300 keV). The time-averaged spectrum from T0-0.5 to T0+0.3 s is best fit by a simple power law function with index -1.45 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (2.0 +/- 0.3)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0-0.064 s in the 10-1000 keV band is 4.3 +/- 0.9 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/39680. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37694] GRB 230509B: 1.3m DFOT Optical observations
by GCN Circulars 12 Mar '25

12 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39679 SUBJECT: GRB 230509B: 1.3m DFOT Optical observations DATE: 25/03/12 06:18:47 GMT FROM: Amit Kumar Ror at ARIES <mitturor77894(a)gmail.com> Amit K. Ror, Anshika Gupta, Pranshu, Shashi B. Pandey, Kuntal Mishra (ARIES) report: We observed the field of GRB 230509B detected by the Swift and Fermi (Evans et al. 2025, GCN 39633; Fermi GBM team, GCN 39635, 39642) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2025-03-10 at 20:25:19 UT, i.e., ~ 1.53 days after the Ferm-GBM trigger. We have taken multiple frames with an exposure time of 300s in the R filter. We stacked the images after the alignment. We detected an optical afterglow reported by Stein et al. 2025 (GCN 39639) in our stacked image. We obtain the following preliminary magnitude in the stacked image: Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude ========================================================= 2025-03-10 20:25:19 ~1.53 R 300s*24 20.36 +/- 0.10 Our detection is consistent with Stein et al. 2025 (GCN 39639); Lipunov et al. 2025 (GCN 39641); Pérez-Fournon et al. 2025 (GCN 39643); Stein et al. 2025 (GCN 39644); Moskvitin et al. 2025 (GCN 39645); Perley et al. 2025 (GCN 39646); Malesani et al. 2025 (GCN 39647); Ducoin et al. 2025 (GCN 39650); Shin et al. 2025 (GCN 39654); Moskvitin et al. 2025 (GCN 39658); Wang et al. 2025 (GCN 39661) and Guiffreda et al. 2025 (GCN 39670). The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue. This circular may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39679. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37693] IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39678 SUBJECT: IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/03/11 21:36:06 GMT FROM: Jessie Thwaites at IceCube/U Wisc-Madison <thwaites(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250309A (https://gcn.nasa.gov/circulars/39631) in a time range of 1000 seconds centered on the alert event time (2025-03-09 07:27:44.750 UTC to 2025-03-09 07:44:24.750 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-250309A. 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-250309A ranges from 1.7e+00 to 1.8e+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 1e+03 GeV and 9e+05 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-03-08 07:36:04.750 UTC to 2025-03-10 07:36:04.750 UTC). In this case, we report a p-value of 1.00, 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-250309A ranges from 1.7e+00 to 1.8e+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/39678. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37692] EP250311a: Global MASTER-Net observations report
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39677 SUBJECT: EP250311a: Global MASTER-Net observations report DATE: 25/03/11 21:18:50 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 EP250311a ( EP Team et al., GCN 39664) errorbox 37833 sec after notice time and 68809 sec after trigger time at 2025-03-11 21:03:08 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 79 deg. The sun altitude is -46.6 deg. The galactic latitude b = 47 deg., longitude l = 354 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2808566 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 68839 | 2025-03-11 21:03:08 | MASTER-SAAO | (14h 55m 03.37s , -02d 44m 11.8s) | C | 60 | 17.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39677. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37691] GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39676 SUBJECT: GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst DATE: 25/03/11 20:10:54 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> James DeLaunay (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250308A onboard (T0: 2025-03-08T18:06:30.72 UTC, CALET/GBM trig 1425492335 GCN 39663, SVOM/GRM GCN 39632) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-45,+45] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 32.5 in a 0.256 s analysis time bin, starting at T0 - 0.064 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 2,693 deg2 and the 50% credible area is 785 deg2. The integrated probability inside the coded field of view is <1%. The NITRATES skymap is consistent with the SVOM/GRM (GCN 39636) and IPN (GCN 39653) localizations. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=763150025/#:~:te… The probability skymap file can be downloaded from the link here [skymap_fits_file](https://guano.swift.psu.edu/files/763150025/0_n_PROBMAP) Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=763150025 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39676. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37690] GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39674 SUBJECT: GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst DATE: 25/03/11 20:10:49 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250228A onboard (T0: 2025-02-28T07:23:46.16 UTC, Fermi GCN 39547) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 8.03 in a 0.128 s analysis time bin, starting at T0 - 0.096 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 14,714 deg2 and the 50% credible area is 5,217 deg2. The integrated probability inside the coded field of view is <1%. The joint NITRATES+GBM localization has a 90% credible area of 1171 deg2 and a 50% credible area of 304 deg2 A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=762420261/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/762420261/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/762420261/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=762420261 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39674. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37689] GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39673 SUBJECT: GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB DATE: 25/03/11 20:10:47 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250226B onboard (T0: 2025-02-26T22:30:23.12 UTC, Fermi GCN 39503, INTEGRAL GCN 39519) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 15.1 in a 1.024 s analysis time bin, starting at T0 + 1.79 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 3,416 deg2 and the 50% credible area is 994 deg2. The integrated probability inside the coded field of view is 6%. The joint NITRATES+GBM localization has a 90% credible area of 165 deg2 and a 50% credible area of 36 deg2 A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=762301858/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/762301858/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/762301858/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=762301858 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39673. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37688] GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39672 SUBJECT: GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB DATE: 25/03/11 20:10:44 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250226A onboard (T0: 2025-02-26T06:34:57.33 UTC, Fermi GCN 39479, GECAM GCN 39492, EP-WXT GCN 39482, INTEGRAL GCN 39518) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 23.9 in a 8.192 s analysis time bin, starting at T0. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 1,797 deg2 and the 50% credible area is 312 deg2. The integrated probability inside the coded field of view is <1%. The joint NITRATES+GBM localization has a 90% credible area of 178 deg2 and a 50% credible area of 51 deg2, and is consistent with the external position by EP-WXT (GCN 39482) A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=762244532/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/762244532/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/762244532/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=762244532 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39672. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37687] GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39671 SUBJECT: GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst DATE: 25/03/11 20:10:42 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> James DeLaunay (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250223B onboard (T0: 2025-02-23T10:19:23.76 UTC, Fermi trig 762615997) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 17.3 in a 16.384 s analysis time bin, starting at T0 - 4.096 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 2,445 deg2 and the 50% credible area is 462 deg2. The integrated probability inside the coded field of view is <1%. The NITRATES skymap is consistent with the Fermi localization reported in the final position notice (GCN 39435). The combined Fermi/GBM+NITRATES 90% credible area is 152 deg2 and the 50% credible area is 46 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=762616028/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/762616028/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/762616028/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=762616028 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/39671. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37686] GRB 250309B: PRIME near-infrared detection
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39670 SUBJECT: GRB 250309B: PRIME near-infrared detection DATE: 25/03/11 19:46:22 GMT FROM: O. Guiffreda at UMD <oriogui(a)umd.edu> GRB 250309B: PRIME near-infrared detection O. Guiffreda (UMD), J. Durbak (UMD), E. Troja (U Rome), A. S. Kutyrev (NASA/GSFC), S. B. Cenko (NASA/GSFC) Following the Fermi GBM trigger (GCN 39635), we observed the transient field in J and H filters with PRIME ~1.5 days after the Fermi detection. At the position of the optical counterpart AT2025dws (Stein et al., GCN 39639), we detect an uncatalogued source in both J-band and H-band. Using nearby VISTA Hemispherical Survey (VHS) stars for preliminary calibration we estimate J~20 AB mag. Further observations are planned. PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023, Durbak et al. 2024). We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39670. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37685] EP250304a: Chandra detection
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39669 SUBJECT: EP250304a: Chandra detection DATE: 25/03/11 18:08:57 GMT FROM: Raffaella Margutti <rmargutti(a)berkeley.edu> R. Margutti (UC Berkeley), S. Pedrami (UC Berkeley), R. Chornock (UC Berkeley), Y. Yao (UC Berkeley), T. Laskar (U of Utah) report: We observed EP250304a (Chen et al., GCN 39580) with the Chandra X-ray Observatory starting on 2025-03-10, 03:13:38 UT (i.e., T0+6.2d, observer frame; 20ks exposure) under a DDT proposal (PI Margutti). An X-ray source is detected with high confidence (>8 sigma Gaussian equivalent) at a location consistent with the EP transient (Zhang et al., GCN 39591). The spectrum is well fitted by a simple power law with photon index Gamma = 2.1 +/- 0.5, similar to previous Swift-XRT observations of this source (Page et al., GCN 39584). For a Gamma=2 index, the inferred 0.3-10 keV flux is ~1.6e-14 erg/s/cm2. These Chandra observations imply that the source has entered a phase of shallower X-ray flux decay compared with the earlier Swift-XRT observations, in close similarity with low-luminosity GRBs. In the soft X-rays, the evolution of EP250304a closely resembles that of the prototypical event GRB060218 (e.g., Campana et al., 2006). We thank the entire CXO team for scheduling these very fast observations, which enabled unique constraints on the later time evolution of the EP source. View this GCN Circular online at https://gcn.nasa.gov/circulars/39669. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37684] GRB 250225B: Swift-BAT refined analysis
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39668 SUBJECT: GRB 250225B: Swift-BAT refined analysis DATE: 25/03/11 18:05:56 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> T. Sakamoto (AGU), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), M. A. Williams (PSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+160 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250225B (trigger #1291459) (Williams et al., GCN Circ. 39473). The BAT ground-calculated position is RA, Dec = 306.134, -41.481 deg which is RA(J2000) = 20h 24m 32.2s Dec(J2000) = -41d 28' 50.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 47%. The mask-weighted BAT light curve shows a bright peak around the trigger time, followed by multiple fainter peaks. After approximately 160 seconds, the GRB was no longer in the BAT field of view (FOV). T90 (15-350 keV) is 110.46 +- 2.12 sec (estimated error including systematics). The time-averaged spectrum from T-0.02 to T+122.46 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.07. The fluence in the 15-150 keV band is 6.5 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+1.31 sec in the 15-150 keV band is 10.4 +- 0.5 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1291459 View this GCN Circular online at https://gcn.nasa.gov/circulars/39668. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37683] GRB 250311A/EP250311a: TRT optical upper limit
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39667 SUBJECT: GRB 250311A/EP250311a: TRT optical upper limit DATE: 25/03/11 12:48:25 GMT FROM: Wenxiong Li at NAOC <liwenxiong1992(a)gmail.com> W.X. Li (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), N.C. Sun, D. Xu, Z. Fan, Y.N. Wang (NAOC), report on behalf of a large collaboration: We observed the field of GRB 250311A/EP250311a detected by MAXI (Tatano et al. GCN 39660) and EP (Mao et al., GCN 39664), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Sierra Remote Observatories in California. Observations started at 12:00:05 UT on 2025-03-11, i.e., ~10 hours after the EP trigger, and 2 x 300s frames were obtained in the R band. No uncatalogued optical source is detected in the stacked R-band image within the EP/WXT error circle, down to the 3-sigma limiting magnitude of R ~ 20. View this GCN Circular online at https://gcn.nasa.gov/circulars/39667. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37682] IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39666 SUBJECT: IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations DATE: 25/03/11 11:59:31 GMT FROM: Ichiro Takahashi at Science Tokyo <itakahashi(a)hp.phys.titech.ac.jp> Ichiro Takahashi (Science Tokyo), Kenta Taguchi (Kyoto U.), Seiji Toshikage, Masaomi Tanaka (Tohoku U.), Yousuke Utsumi (NAOJ), Ryosuke Itoh (Ibara City), Tomoki Morokuma (ARC/Chitech) report on behalf of a larger collaboration: We performed optical imaging observations of the localization area of IceCube-250309A (GCN 39631) using the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno and the Tricolor CMOS Camera and Spectrograph (TriCCS) on the 3.8-m Seimei telescope. We started our observations at UT 2025-03-09 14:29 (MITSuME) and 2025-03-09 16:53 (Seimei), about 6.9 and 9.3 hours after the event, respectively. The observations with MITSuME covered the 90% probability region with 4 pointings while the observations with Seimei covered about half of the 90% probability region with 15 pointings. The data reduction and detailed examination of the data are underway. View this GCN Circular online at https://gcn.nasa.gov/circulars/39666. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37681] GRB 250311A: Tiled Swift observations
by GCN Circulars 11 Mar '25

11 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39665 SUBJECT: GRB 250311A: Tiled Swift observations DATE: 25/03/11 11:30:09 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 MAXI GRB 250311A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00135 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 MAXI 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/39665. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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