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

[vsnet-grb-info 40144] GRB 251003A: LCOGT Optical Detection
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42074 SUBJECT: GRB 251003A: LCOGT Optical Detection DATE: 25/10/03 04:04:06 GMT FROM: Robert Strausbaugh at Eastern Illinois University <rstrausbaugh(a)eiu.edu> R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration: We observed the Swift GRB 251003A field (Beardmore et al., GCN 42070) with the LCOGT 1-meter Sinistro instrument at the McDonald Observatory, USA site, on October 3, from 03:07 to 03:39 UT (corresponding to 1.15 to 1.68 hours after the GRB trigger time) with the SDSS i and r filters. We performed a series of 3x300s exposures in i-band and r-band. We detect an uncatalogued source in the XRT enhanced error region (Evans et al. GCNC 42071) consistent with other optical counterpart observations (Aceituno et al., GCN 42072; Méndez et al., GCN 42073) in both bands. We note that the r-i color of this event may indicate a moderate redshift source (z>4). The following magnitudes are calculated using the PanSTARRS catalog as reference: r = 20.97 +/- 0.12 i = 19.25 +/- 0.04 These magnitudes are not corrected for galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42074. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40143] GRB 251003A: COLIBRÍ optical detection of the fading afterglow
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42073 SUBJECT: GRB 251003A: COLIBRÍ optical detection of the fading afterglow DATE: 25/10/03 03:55:12 GMT FROM: enriquemm(a)astro.unam.mx Enrique Moreno Méndez (UNAM), Benjamin Schneider (LAM), Camila Angulo (UNAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM): We imaged the field of the Swift GRB 251003A (Beardmore et al., GCN Circ. 42070) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-10-03 02:19 to 02:22 UTC (from 0.3 to 0.7 hours after the trigger) and obtained 3 minutes of simultaneous exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detected the optical counterpart reported by Aceituno et al., GCN Circ. 42072, at a position of RA, Dec = 18.52939, 56.49110 (J2000), with preliminary magnitudes of: r = 20.34 +/- 0.11 z = 18.56 +/- 0.05 The object fades in subsequent observations, confirming that it is the optical afterglow. The very red color suggests that this might be either a moderate redshift GRB with a drop-out in r or a very heavily reddened GRB. Further observations in g/r/i/z/y are ongoing. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42073. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40142] GRB 251003A: 1.5m OSN afterglow candidate
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42072 SUBJECT: GRB 251003A: 1.5m OSN afterglow candidate DATE: 25/10/03 03:06:40 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es> F. J. Aceituno, R. Sanchez-Ramirez A. J. Castro-Tirado, S. Guziy, M.D. Caballero-Garcia, S.-Y. Wu and I. Perez-Garcia (IAA-CSIC), and Y.-D. Hu (GXI), on behalf of a larger collaboration, report: Following the detection of GRB 251003A by both Fermi (Fermi team, GCNC 42069) and Swift (Beardmore et al. GCNC 42070), we obtained a 300s exposure image (I-band) with the 1.5m OSN telescope in Sierra Nevada (Granada, Spain) starting on Oct 3 (02:34 UT, i.e. 36 min post burst). At the enhanced X-ray position (Evans et al. GCNC 42071) we identify an optical source with a preliminary magnitude of 21, which we propose to be the afterglow to GRB 251003A. Further observations are being gathered. View this GCN Circular online at https://gcn.nasa.gov/circulars/42072. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40141] GRB 251003A: Prompt enhanced Swift-XRT position
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42071 SUBJECT: GRB 251003A: Prompt enhanced Swift-XRT position DATE: 25/10/03 02:22:53 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-XRT team: Using 263 s of promptly downlinked XRT event data for GRB 251003A, we find an enhanced XRT position of the afterglow: RA, Dec: 18.52838, 56.49082 which is equivalent to: RA (J2000) = 01 14 06.81 Dec (J2000) = +56 29 26.9 with an uncertainty of 2.3 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/1400964. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42071. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40140] GRB 251003A: Swift detection of a burst
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42070 SUBJECT: GRB 251003A: Swift detection of a burst DATE: 25/10/03 02:10:50 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> A. P. Beardmore (U Leicester), R. Gupta (NASA GSFC), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 01:58:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 251003A (trigger=1400964). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 18.503, +56.507 which is RA(J2000) = 01h 14m 01s Dec(J2000) = +56d 30' 23" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~1835 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 01:59:42.1 UT, 72.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 18.52734, 56.49009 which is equivalent to: RA(J2000) = 01h 14m 06.56s Dec(J2000) = +56d 29' 24.3" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 77 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 consistent with the Galactic value of 4.39 x 10^21 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 1.66e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 78 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 0.408. Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 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/42070. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40139] GRB 251003A: Fermi GBM Final Real-time Localization
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42069 SUBJECT: GRB 251003A: Fermi GBM Final Real-time Localization DATE: 25/10/03 02:09:08 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 01:58:31 UT on 3 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251003A (trigger 781149516.956282 / 251003082). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 31.9, Dec = 49.6 (J2000 degrees, equivalent to J2000 02h 07m, 49d 36'), with a statistical uncertainty of 18.2 degrees. The angle from the Fermi LAT boresight is 64.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251003082/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251003082/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251003082/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42069. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40138] Swift GRB251003.08: Global MASTER-Net observations report
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42068 SUBJECT: Swift GRB251003.08: Global MASTER-Net observations report DATE: 25/10/03 02:04:38 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, 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.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB251003.08 (trigger No 1400964,01h 14m 00.72s , +56d 30m 25.2s, R=0.05) errorbox 10 sec after notice time and 34 sec after trigger time at 2025-10-03 01:59:04 UT, with upper limit up to 16.6 mag. Observations started at twilight. The observations began at zenith distance = 43 deg. The sun altitude is -13.7 deg. The galactic latitude b = -6 deg., longitude l = 126 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3005736 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 40 | MASTER-Kislovodsk | P- | 10 | 15.8 | 50 | MASTER-Kislovodsk | P- | 30 | 16.4 | Coadd 40 | MASTER-Kislovodsk | P| | 10 | 14.6 | 58 | MASTER-Kislovodsk | P- | 10 | 16.0 | 58 | MASTER-Kislovodsk | P| | 10 | 15.0 | 77 | MASTER-Kislovodsk | P- | 10 | 16.2 | 77 | MASTER-Kislovodsk | P| | 10 | 15.1 | 100 | MASTER-Kislovodsk | P- | 20 | 16.5 | 100 | MASTER-Kislovodsk | P| | 20 | 15.8 | 129 | MASTER-Kislovodsk | P- | 20 | 16.5 | 129 | MASTER-Kislovodsk | P| | 20 | 15.6 | 162 | MASTER-Kislovodsk | P- | 30 | 16.6 | 162 | MASTER-Kislovodsk | P| | 30 | 15.9 | The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42068. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40137] Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
by GCN Circulars 03 Oct '25

03 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42067 SUBJECT: Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters DATE: 25/10/03 01:27:07 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Senik, V. Lipunov, E.Gorbovskoy, A.Kuznetsov, I.Panchenko, P.Balanutsa, N.Tiurina, A.Sankovich, G.Antipov, Yu. Tselik, A. Sosnovskiy, M.Shilova, A.Chasovnikov, V.Topolev, K.Zhirkov, Ya.Kechin, V.Senik, D.Vlasenko(Lomonosov MSU, SAI, Moscow), R.Podesta, C.Francile, F. Podesta, E. Gonzalez (OAFA, San Juan Uni.,Argentina); D.Buckley, (SAAO, South Africa) O.Gress, N.Budnev (ISU, Irkutsk), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias, Spain), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,J.Martinez,A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) The MASTER-Kislovodsk robotic telescope of the MASTER Global Robotic Net [1], [2] started Fermi GRB 251002A (trigger 781128896, Ttrigger=2025-10-02 20:14:51UT) at 2025-10-02 20:19:42 (Lipunov et al. GCN 42059, cover map and OT https://master.sai.msu.ru/site/master2/event.php?id=3005541&action=12&SAT=S… ) in two mutually perpendicular polarization filters. There is MASTER OT J005537.81-053401.0 since the first image with unfiltered m_OT~17.2 at 2025-10-02 20:22:09.308(not first time) with preliminary detected polarization. This OT was first publishied (discovered) by SVOM (GCN 42061), and also by LCO (Turpin et al. GCN 42062), FREM-ORM (Jelinek et al. GCN 42063), SAO RAS (Moskvitin et al. GCN 42065) and BOOTES (Perez-Garcia et al. GCN 42066) Observations and reduction will be continued. [1] Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L [2] V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina,A.S.Kuznetsov 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http://www.pereplet.ru/lipunov/625.html#625 View this GCN Circular online at https://gcn.nasa.gov/circulars/42067. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40136] GRB 251002A: BOOTES-6 early optical detection
by GCN Circulars 02 Oct '25

02 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42066 SUBJECT: GRB 251002A: BOOTES-6 early optical detection DATE: 25/10/02 23:27:43 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, S.-Y. Wu, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), M. Gritsevich (Univ. of Helsinki) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report: Following the detection of GRB 251002A by SVOM (Saccardi et al., GCN 42060), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) responded to this high-energy event starting on Oct 2, 20:17:55 UT (i.e., 186 sec after detection). Series of images in clear filter were gathered and we detect an optical source consistent with the one reported by Palmerio et al. (GCN 42061), Turpin et al. (GCN 42062), Jelinek et al. (GCN 42063), Juliá-Maroto et al. (GCN 42064) and Moskvitin et al. (GCN 42065). Using GaiaDR3 Gmag as reference we report our photometry analysis: | UT mid exposure | mag | error | filter | exposure time (sec) | | ------------------- | ----- | ----- | ------ | ------------------- | | 2025-10-02 20:18:25 | 15.47 | 0.03 | clear | 60 | | 2025-10-02 20:19:53 | 15.79 | 0.03 | clear | 60 | | 2025-10-02 20:21:21 | 16.16 | 0.05 | clear | 60 | Further analysis of the additional images is ongoing. We thank the staff at Boyden Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/42066. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40135] GRB 251002A: SAO RAS optical observations
by GCN Circulars 02 Oct '25

02 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42065 SUBJECT: GRB 251002A: SAO RAS optical observations DATE: 25/10/02 23:10:11 GMT FROM: Alexander Moskvitin at SAO RAS <mosk(a)sao.ru> A. S. Moskvitin (SAO RAS), V. P. Goranskij (SAI MSU), V. V. Vlasyuk, V. S. Shergin, V. A. Egorov, M. A. Pritychenko, I. V. Afanasieva (SAO RAS), report on behalf of GRB follow-up collaboration. We observed the field of the GRB 251002A (Saccardi et al., GCN 42060) with the 1-m SAO RAS telescope Zeiss-1000 equipped with the new CCD-photometer. The observations started at 20:31:30 UT, ~17 minutes after the trigger. The optical transient (Palmerio et al., GCN 42061; Turpin et al., GCN 42062; Jelinek et al., GCN 42063; Juliá-Maroto et al., GCN 42064) is clearly detected in the individual images with the brightness of R = 17.58 +/- 0.02 (t_mid - T0 = 0.41694 hours). Preliminary photometry is based on the nearby SDSS objects (magnitudes converted with Lupton 2005 equations) and has not corrected for the Galactic extinction. The observations with the 1-m telescope in BVRI filters and also with the 0.5-m telescope AS-500/2 are ongoing. We are grateful to the SAO RAS staff for their technical support. View this GCN Circular online at https://gcn.nasa.gov/circulars/42065. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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