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

[vsnet-grb-info 36777] GRB 250101A: Swift/UVOT Detection
by GCN Circulars 02 Jan '25

02 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38775 SUBJECT: GRB 250101A: Swift/UVOT Detection DATE: 25/01/02 07:11:25 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250101A 133s after the BAT trigger (Page et al., GCN Circ. 38752). A fading source consistent with the XRT position (Goad et al., GCN Circ. 37761) and the previously reported optical source, since confirmed by multiple observations (Li et al., GCN Circ. 38753; Mohan et al., GCN Circ. 38754; Zhu et al., GCN Circ., 38755; Wu et al., GCN Circ 38578; Moskvitin & Spiridonova, GCN Circ. 38762; Odeh et al., GCN Circ 38763; Hu et al., GCN Circ. 38764; D'Avino & L. Izzo, GCN Circ. 38768; Escudero-Coca, GCN Circ. 38769; Leonini et al., GCN Circ. 38771) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 02:28:16.47 = 37.06864 (deg.) Dec (J2000) = +19:11:39.6 = 19.19433 (deg.) with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 133 283 147 18.03 +/- 0.05 v 620 813 39 18.10 +/- 0.28 b 546 738 39 18.66 +/- 0.21 u 291 540 246 17.93 +/- 0.08 w1 670 5019 235 >19.8 m2 4614 4814 197 >19.1 w2 596 4404 216 >18.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.164 in the direction of the burst (Schlegel et al. 1998). We note that the lack of detection in the NUV bands for this bright burst would be consistent with the redshift of z=2.49 reported by Zhu et al. (GCN Circ. 38759). View this GCN Circular online at https://gcn.nasa.gov/circulars/38775. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36776] GRB 250101A: 1.6m Mephisto multi-band optical followup
by GCN Circulars 02 Jan '25

02 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38774 SUBJECT: GRB 250101A: 1.6m Mephisto multi-band optical followup DATE: 25/01/02 05:41:08 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Jinghua Zhang, Guowang Du, Yangwei Zhang, Xufeng Zhu, Fanchuan Kong, Chenxi Shang,Yuan Fang, Xinlei Chen, Xingzhu Zou, Yu Pan, Brajesh Kumar, Yuanpei, Yang, Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team: We performed simultaneous multi-band photometric observations of GRB 250101A detected by Swift/BAT (Page et. al., GCN 38752) with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. The observations were initiated at 13:26:07 UTC 2025-01-01 (i.e., 197 s after the Swift/BAT trigger) and continuously followed-up for several hours. Multiple frames were obtained in uvgriz bands. The optical counterpart is clearly detected in all bands. The photometry of the initial frames is the following: UT start band Exp Mag(AB) 2025/01/01T13:26:07 u 180s 18.66 +/- 0.04 2025/01/01T13:26:08 g 50s 17.07 +/- 0.01 2025/01/01T13:26:08 i 79s 16.30 +/- 0.01 2025/01/01T13:30:02 v 180s 18.59 +/- 0.03 2025/01/01T13:30:04 r 50s 17.30 +/- 0.02 2025/01/01T13:30:04 z 79s 16.73 +/- 0.05 Our results are consistent with the previously reported circulars (Li et al., GCN 38753; Mohan et al., GCN 38754; Zhu et al., GCN 38755; Budnev et al., GCN 38756; Wu et al., GCN 38758; Moskvitin et al., GCN 38762; Odeh et al., GCN 38763, Hu et al., GCN 38764; D'Avino et al., GCN 38768; Escudero-Coca et al., GCN 38769). Further analysis of the additional images is ongoing. -------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21. -------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/38774. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36775] GRB 250101A: Swift-XRT refined Analysis
by GCN Circulars 02 Jan '25

02 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38773 SUBJECT: GRB 250101A: Swift-XRT refined Analysis DATE: 25/01/02 02:14:48 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.8 ks of XRT data for GRB 250101A, from 110 s to 39.2 ks after the BAT trigger. The data comprise 10 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.8 (+/-0.7). At T+249 s the decay flattens to an alpha of 0.06 (+0.29, -0.74) before breaking again at T+909 s to a final decay with index alpha=0.79 (+0.13, -0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.02 (+0.18, -0.17). The best-fitting absorption column is 1.7 (+1.3, -1.1) x 10^22 cm^-2, at a redshift of 2.49, in addition to the Galactic value of 1.4 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 1.4 x 10^21 cm^-2 Intrinsic column: 1.7 (+1.3, -1.1) x 10^22 cm^-2 at z=2.49 Photon index: 2.02 (+0.18, -0.17) If the light curve continues to decay with a power-law decay index of 0.79, the count rate at T+24 hours will be 0.018 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.4 x 10^-13 (9.1 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01278305. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/38773. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36774] Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
by GCN Circulars 02 Jan '25

02 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38772 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB DATE: 25/01/02 01:47:08 GMT FROM: sumanbala2210(a)gmail.com S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 757464861/250101954 at 22:54:16.69 UT on 01 January 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/38772. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36773] GRB 250101A: Montarrenti Observatory optical observations and rebrightening
by GCN Circulars 02 Jan '25

02 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38771 SUBJECT: GRB 250101A: Montarrenti Observatory optical observations and rebrightening DATE: 25/01/02 01:29:17 GMT FROM: Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini(a)iol.it> S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), 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: We observed the field of GRB 250101A (Swift trigger 1278305, Page et al., GCN 38752) with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88). The observations were started at 2025-01-01 18:03:48 UT (approximately 4.66 hours after burst) stacking a set of Rc-band CCD images. Observations were performed under thin cloud cover in the second part of the night. The OT was detected at the following position: RA (J2000.0) 02h 28m 16.56s +/-0.05 Decl. (J2000.0) +19° 11' 39.82" +/-0.14 Preliminary photometry was obtained using nearby PanSTARRS stars as follows: Observation Mid-Time T-T0 (hr) Exposure Filter Mag. Err. 2025-01-01 18:18:09 UT 4.92 40x40s Rc 20.09 +/-0.09 2025-01-01 18:47:18 UT 5.40 43x40s Rc 20.09 +/-0.10 An optical rebrightening was observed as follows: Observation Mid-Time T-T0 (hr) Exposure Filter Mag. Err. 2025-01-01 19:45:22 UT 6.37 36x40s Rc 19.63 +/-0.08 Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied. Our observations are consistent with other already reported (Li et al., GCN 38753; Mohan et al., GCN 38754; Zhu et al., GCN 38755; Budnev et al., GCN 38756; Wu et al., GCN 38758; Moskvitin et al., GCN 38762; Odeh et al., GCN 38763, Hu et al., GCN 38764; D'Avino et al., GCN 38768; Escudero-Coca et al., GCN 38769), included those of the optical brightening (Moskvitin et al., GCN 38765). View this GCN Circular online at https://gcn.nasa.gov/circulars/38771. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36772] IceCube-250101A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 02 Jan '25

02 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38770 SUBJECT: IceCube-250101A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/01/02 01:23:00 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2025-01-01 at 21:04:57.73 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.9213 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/140312_53817657.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2025-01-01 Time: 21:04:57.73 UT RA: 318.96 (+0.64, -0.63 deg 90% PSF containment) J2000 Dec: -0.93 (+0.49, -0.44 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. There is one Fermi 4FGL-DR4 or 3FHL catalog source in the 90% uncertainty region: 4FGL J2115.9-0113 at RA: 319.00 deg, Dec: -1.23 deg J2000 (0.3 deg away from the best-fit event position). The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu View this GCN Circular online at https://gcn.nasa.gov/circulars/38770. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36771] GRB 250101A: LCOGT optical afterglow detection
by GCN Circulars 02 Jan '25

02 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38769 SUBJECT: GRB 250101A: LCOGT optical afterglow detection DATE: 25/01/02 00:15:46 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> P. Escudero-Coca, B. Armas-Chinea, F. Dobrindt, G. Fernández-Rodríguez, Á. García Lozano, A. Huertas Ferrer, C. Méndez-Lapido, I. Ortega-Casas, M. Torreiro Martínez, G. Villa (ULL), S.R. Berlanas, F. Poidevin, and I. Pérez-Fournon (IAC and ULL) We report on optical imaging of the field of GRB 250101A, discovered by Swift BAT (Page et al., GCN #38752), with the Las Cumbres Observatory global telescope network (LCOGT) 40-cm telescope located at the LCOGT node at Sutherland Observatory (South Africa). The observation, a single 600-sec exposure in the SDSS r' filter, started on 2025-01-01 19:56:30 UT, i.e. ~ 6.56 hr after the Swift BAT trigger. We detect the optical afterglow at a position consistent with the Swift UVOT position reported by Page et al. (GCN #38752). We measure a magnitude of r' = 19.96 +/- 0.16 calibrated against PanSTARRS DR1 stars and not corrected for Galactic extinction. This result is consistent with other reports: Li et al., GCN 38753; Mohan et al., GCN 38754; Zhu et al., GCN 38755; Budnev et al., GCN 38756; Wu et al., GCN 38758; Moskvitin and Spiridonova, GCN 38762; Odeh and Guessoum, GCN 38763; Hu et al., GCN 38764; and D'Avino and Izzo, GCN 38768. A rebrightening in the optical has been reported by Moskvitin et al. (GCN 38765). The spectroscopic redshift of z = 2.49 has been obtained by Zhu et al. (GCN 38759). These results are based on observations made with the Las Cumbres Observatory’s education network telescopes that were upgraded through generous support from the Gordon and Betty Moore Foundation and are part of a course on Astrophysical Techniques of the Master in Astrophysics of the Universidad de La Laguna, Tenerife, Spain (LCOGT observing programme IAC2024B-010, ULL-ASTRO-MASTER). View this GCN Circular online at https://gcn.nasa.gov/circulars/38769. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36770] GRB 250101A: OASDG optical observations
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38768 SUBJECT: GRB 250101A: OASDG optical observations DATE: 25/01/01 23:37:38 GMT FROM: luca.izzo(a)inaf.it L. D'Avino (OASDG/AstroCampania), and L. Izzo (INAF-OACn and DARK/NBI) report: We observed the field of GRB 250101A (Page et al., GCN #38752) using the 0.5-m T1 telescope of the Osservatorio Astronomico S. Di Giacomo, located in Agerola, Italy. Our observations started on 2025 January 1 at 16:57 UT, approximately 3.6 hours after the GRB trigger. We acquired a series of 8x300 s frames in the Rc and Ic filters. In the stacked images, we clearly detect the optical counterpart initially identified by Swift-UVOT (Page et al., GCN #38752) and reported by several other telescopes (Li et al., GCN #38753; Mohan et al., GCN #38754; Zhu et al., GCN #38755; Budnev et al., GCN #38756; Wu et al., GCN #38758; Zhu et al., GCN #38759; Moskvitin et al., GCN #38762, GCN #38765; Odeh & Guessoum, GCN #38763; Hu et al., GCN #38764). We measure a preliminary magnitude of Rc = 20.00 +/- 0.07 mag (AB), calibrated against nearby stars from the Pan-STARRS catalog, appropriately transformed to Rc and Ic magnitudes. View this GCN Circular online at https://gcn.nasa.gov/circulars/38768. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36769] Fermi GRB 250101B: Global MASTER-Net observations report
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38767 SUBJECT: Fermi GRB 250101B: Global MASTER-Net observations report DATE: 25/01/01 23:30:44 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-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 250101B ( Fermi GBM team, GCN 38766) errorbox 30 sec after notice time and 72 sec after trigger time at 2025-01-01 23:15:25 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 46 deg. The sun altitude is -34.5 deg. The galactic latitude b = -29 deg., longitude l = 201 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2730742 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 78 | 2025-01-01 23:15:25 | MASTER-SAAO | (04h 55m 50.35s , -02d 10m 31.1s) | C | 10 | 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/38767. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36768] GRB 250101B: Fermi GBM Final Real-time Localization
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38766 SUBJECT: GRB 250101B: Fermi GBM Final Real-time Localization DATE: 25/01/01 23:24:52 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 23:14:12 UT on 1 Jan 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250101B (trigger 757466057.652354 / 250101968). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 70.9, Dec = -3.2 (J2000 degrees, equivalent to J2000 04h 43m, -3d 12'), with a statistical uncertainty of 3.3 degrees. The angle from the Fermi LAT boresight is 49.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250101968/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250101968/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250101968/… View this GCN Circular online at https://gcn.nasa.gov/circulars/38766. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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