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

[vsnet-grb-info 38896] GRB 250625A: Swift-BAT refined analysis
by GCN Circulars 27 Jun '25

27 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40852 SUBJECT: GRB 250625A: Swift-BAT refined analysis DATE: 25/06/27 23:16:03 GMT FROM: Amy <yarleen(a)gmail.com> A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), M. Ferro (INAF-OAB), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+100 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250625A (trigger #1327910) (Ferro et al., GCN Circ. 40825). The BAT ground-calculated position is RA, Dec = 261.517, 22.245 deg which is RA(J2000) = 17h 26m 04.1s Dec(J2000) = +22d 14' 40.7" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 68%. The mask-weighted light curve shows a single-pulse structure that starts at ~T0, peaks at ~T+2 s, and ends at ~T+6 s. T90 (15-350 keV) is 4.00 +- 1.41 sec (estimated error including systematics). The time-averaged spectrum from T-0.35 to T+3.65 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.00 +- 0.22. The fluence in the 15-150 keV band is 2.8 +- 0.4 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+1.65 sec in the 15-150 keV band is 0.8 +- 0.2 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/1327910 View this GCN Circular online at https://gcn.nasa.gov/circulars/40852. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38895] GRB 250625A: Leavitt Observatory afterglow detection
by GCN Circulars 27 Jun '25

27 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40851 SUBJECT: GRB 250625A: Leavitt Observatory afterglow detection DATE: 25/06/27 19:20:11 GMT FROM: leavittob(a)gmail.com L. Moretti, E. Pavoni (Leavitt Observatory, Italy) Members of: GRB/UAI - Gamma Ray Burst Section of Unione Astrofili Italiani ATA - Associazione Tuscolana di Astronomia In a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), report: We imaged the field of GRB 250625A, which was detected by Swift-BA (Ferro et al., GCN 40825) and Fermi-GBM (GCN 40824) with our RC telescope (D=250 mm, F/D=8) of Leavitt Observatory. The observations began approximately 4.6 hours after the trigger, with good weather conditions, stacking a series of 12 exposures of 120 seconds each. All images are unfiltered and were processed by a single data processing pipeline based on astropy package (Astropy Collaboration et al., 2022ApJ...935..167A). In the stacked frame, we detected a very faint object at the following position: R.A. (J2000) = 17:26:01.92 Dec. (J2000) = +22:16:04.31 with the following photometry: Date UT at mid-exposure Filter Mag. Err. 2025-06-25 20:58:29 UTC CR 21.4 +/-0.2 CR magnitude is unfiltered with R zero point. Magnitudes were estimated with the Pan-STARRS cat. and are derived using Lupton (2005) equations. Not corrected for galactic dust extinction. This measure is consistent with the optical afterglow reported by Moskvitin et al. (GCN 40828), Xin et al. (GCN 40830), Zhu et al. (GCN 40834), Fortin et al. (GCN 40837), Adami et al. (GCN 40838), Brosio et al. (GCN 40839), Wang et al. (GCN 40841), Ruocco et al. (GCN 40843), de Ugarte Postigo et al. (GCN 40846). The message may be cited. Reference: https://leavittobservatory.altervista.org View this GCN Circular online at https://gcn.nasa.gov/circulars/40851. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38894] Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
by GCN Circulars 27 Jun '25

27 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40850 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB DATE: 25/06/27 17:30:12 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 772732642/250627665 at 15:57:17.97 UT on 27 June 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/40850. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38893] Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB
by GCN Circulars 27 Jun '25

27 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40849 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB DATE: 25/06/27 13:51:38 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> M. Dafcikova (MUNI) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 772720540/250627525 at 12:35:35.78 UT on 27 June 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/40849. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38892] GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
by GCN Circulars 27 Jun '25

27 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40848 SUBJECT: GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations DATE: 25/06/27 11:55:09 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Tarasenkov (INASAN), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 250625A (Fermi GBM Team, GCN 40824; Ferro et al., GCN 40825; Beardmore et al., GCN 40827; Dichiara et al., GCN 40835; Di Lalla et al., GCN 40836) using the 0.7-meter AS-32 telescope of Abastumani Observatory (AbAO) and the 0.5-meter RC-500 telescope of INASAN Kislovodsk Observatory. The observations at AbAO started on 2025-06-25 at 17:41:35 UT and consisted of 71*60 sec exposures. The observations at RC-500 were carried out between 2025-06-25 18:19:40 UT and 2025-06-26 00:09:04 UT using 120 sec exposures. We do not detect the optical afterglow reported/followed by (Moskvitin et al., GCN 40828, Xin et al., GCN 40830; Malesani et al., GCN 40831; Lipunov et al., GCN 40826/40832; Zhu et al., GCN 40834, Fortin et al., GCN 40837; Adami et. al, GCN 40838; Brosio et. al, GCN 40839; Breeveld & Ferro, GCN 40840; WU et. al, GCN 40842; Ruocco et. al, GCN 40843; de Ugarte Postigo et. al, GCN 40846) in the R-band co-add images. The preliminary photometry is as follows: Date UT start t-T0 Exp. Filter OT Err. UL Telescope (mid, days) (n*s) (3sigma) 2025-06-25 17:41:35 0.09176 71*60 R n/d n/d 20.0 AS-32 2025-06-25 18:38:08 0.14735 59*120 R n/d n/d 21.5 RC-500 The photometry has calibrated using stars from USNO-B1.0 (see Moskvitin et al., GCN 40828) and has not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40848. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38891] The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
by GCN Circulars 27 Jun '25

27 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40847 SUBJECT: The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg DATE: 25/06/27 04:28:06 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> B.-T. Wang (YNAO,CAS), J. H. Wu (GZHU), W. F. Wen(SZTU), J. W. Hu, Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709179435 at the time of 2025-06-27T03:38:47, is likely a new outburst associated with CV SS Cyg. The estimated flux of the outburst is around 2e-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 3e+32 erg/s. 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/40847. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38890] GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40846 SUBJECT: GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy DATE: 25/06/26 23:08:02 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> A. de Ugarte Postigo (LAM), A. Martin-Carrillo (UCD), D. B. Malesani (DAWN/NBI and Radboud), J. F. Agui Fernandez (CAHA), M. A. Aloy (UV), J. P. U. Fynbo (DAWN/NBI), L. Galbany (IEEC-CSIC), S. Geier (GTC), B. Schneider (LAM), L. Izzo (INAF/OACN and DARK/NBI), G. Lombardi (GTC), N. A. Rakotondrainibe (LAM), N. R. Tanvir (Univ. Leicester), C. C. Thoene (AbAO), F. Pérez (GTC), D. Pérez Valladares (GTC) and A. Cabrera Lavers (GTC) report: We observed the optical afterglow of the GRB 250607A detected by Fermi/GBM and Swift/BAT (Fermi GBM team, GCN 40824; Ferro et al., GCN 40825) using the 10.4 m GTC located at the Roque de los Muchachos Observatory in the island of La Palma (Spain) equipped with the OSIRIS+ instrument. In a 3x30 s acquisition image in the z-band, with a mean time of 2025-06-26T01:09:07 (~9.07 hr after the Swift trigger), we detect two objects consistently with the Swift/XRT position (REF). The first is the optical afterglow reported by Moskvitin et al. (GCN 40828), Xin et al. (GCN 40830), Zhu et al. (GCN 40834), Fortin et al. (GCN 40837), Adami et al. (GCN 40838) and Brosio et al. (GCN 40839), for which we measure a magnitude z = 23.75 +/- 0.20 (AB, calibrated against nearby Legacy Survey objects). The second (at RA =17:26:02.17, Dec = +22:16:02.8) has an AB magnitude z = 23.69 +/- 0.18, with a separation of ~1.4" from the afterglow. Our spectroscopic observations started on 2025-06-26T01:44:27.5 UT (9.67 hr after the Swift trigger) and consisted of 3x1200 s exposures using grism R1000R, covering the range between 5100 and 10,000 AA. In the acquisition process, the slit was placed on top of this second object, not the afterglow. For this target, in a preliminary reduction of the spectra, we detect a continuum and a few emission lines, including the [O II] doublet, [O III] 5008 and H-beta, from which we infer a redshift of z = 0.655. At this distance, if this galaxy is associated with the optical afterglow, the offset between the galaxy and the optical afterglow would be ~10 kpc. We note that the probability of chance coincidence is not negligible (~2.5%). We cannot thus conclude that GRB 250625A is at redshift z = 0.655. Further observations to confirm their association are planned and encouraged. We thank Liping Xin (NAOC) for sharing accurate coordinates of the afterglow from SVOM/VT. View this GCN Circular online at https://gcn.nasa.gov/circulars/40846. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38889] GRB 250626A: Fermi GBM Final Real-time Localization
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40845 SUBJECT: GRB 250626A: Fermi GBM Final Real-time Localization DATE: 25/06/26 22:24:29 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely SHORT GRB At 22:13:53 UT on 26 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250626A (trigger 772668838.960546 / 250626926). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 35.5, Dec = -6.6 (J2000 degrees, equivalent to J2000 02h 22m, -6d 35'), with a statistical uncertainty of 19.9 degrees. The angle from the Fermi LAT boresight is 58.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250626926/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250626926/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250626926/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40845. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38888] Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40844 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB DATE: 25/06/26 17:15:57 GMT FROM: eliza.neights(a)gmail.com E. Neights (GWU, NASA GSFC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 772647532/250626680 at 16:18:47.72 UT on 26 June 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/40844. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38887] GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40843 SUBJECT: GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart DATE: 25/06/26 17:11:34 GMT FROM: Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde(a)gmail.com> Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy) and K. Kalinowski (Aarhus University, Department of Physics and Astronomy) report: Following the Swift trigger no. 1327910 (GCN 40825 M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), J. J. DeLaunay (PSU),R. Gupta (NASA GSFC), J. A. Kennea (PSU), D. M. Palmer (LANL),B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf ofthe Neil Gehrels Swift Observatory Team) from the Swift Burst Alert Telescope (BAT), we pointed at the coordinates RA(J2000)=17h 26m 02.09s: Dec(J2000)= +22d 16' 03.5" and started our observations with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: AAVSO - American Association of Variable Star Observers. GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. The observations started at 19:30 UT of 2025/06/25, after about 3.30 hours after the GRB trigger, with clear sky, with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME I took 13 unfiltered images of 120 sec . Start End 19:30:01 UT 19:56:45 UT All images, calibrated with masterdark and masterflat have been measured with Thycho Tracker software We have detected a faint source at the enhanced position reported by Swift Burst Alert Telescope (BAT) at following position RA (J2000.0) 17 26 02.13 Dec (J2000.0) +22 16 07.7 with the following photometry and astrometry: GRB 250625A 17 26 02.13 +22 16 07.7 20.2 V C82 Magnitudes were estimated with the ATLAS cat. and are not corrected for galactic dust extinction. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40843. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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