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

[vsnet-grb-info 38358] GRB 2025050: Swift ToO observations
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40329 SUBJECT: GRB 2025050: Swift ToO observations DATE: 25/05/03 04:45:12 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the SVOM/ECLAIRs-detected event GRB 2025050. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021827 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the SVOM/ECLAIRs event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40329. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38357] GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40328 SUBJECT: GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163 DATE: 25/05/03 02:52:49 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> A. de Ugarte Postigo (LAM), J. F. Agui Fernandez (CAHA), C. C. Thoene (AbAO), B. Schneider (LAM), N. A. Rakotondrainibe (LAM), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), M. A. Aloy (UV), J. P. U. Fynbo (DAWN/NBI), L. Galbany (IEEC-CSIC), S. Geier (GTC), L. Izzo (INAF/OACN and DARK/NBI), G. Lombardi (GTC), N. R. Tanvir (Univ. Leicester), A. Tejero (GTC) and D. Garcia-Alvarez (GTC) report We observed the afterglow of the SVOM GRB 250502A (Wang et al. GCN 40313; Rakotondrainibe et al. GCN 40315; An et al. GCN 40319; Li et al. GCN 40320; Ghosh et al. GCN 40322) using OSIRIS+ on the 10.4m GTC telescope, at Roque de los Muchachos Observatory (La Palma, Spain). The observation started at 2025-05-03T00:34:49 UT (15.806 hrs after the burst) and consisted of acquisition imaging in r-band followed by 3x1200s exposures of spectroscopy using grism R1000B, covering the range between 3600 and 7800 AA at a resolving power of ~ 600. In the acquisition image the afterglow is detected at an AB magnitude of r = 21.00 +/- 0.03, as compared to PanSTARRS field stars. The spectrum shows a clear continuum over the complete spectral range with multiple absorption features that we identify as Ly-alpha, SII, OI, SiII, SiII*, CII, SiIV, CIV, FeII, FeII*, AlII, AlIII at a common redshift of z = 2.163, which we identify as the redshift of the GRB. We also note the presence of a prominent emission of Lyman alpha. View this GCN Circular online at https://gcn.nasa.gov/circulars/40328. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38356] GRB 250502C: Fermi GBM Final Localization
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40327 SUBJECT: GRB 250502C: Fermi GBM Final Localization DATE: 25/05/02 18:51:11 GMT FROM: eliza.neights(a)gmail.com The Fermi GBM team reports the detection of a likely SHORT GRB "At 07:23:59.29 UT on 02 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250502C (trigger 767863444/250502308). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 239.16, Dec = -47.34 (J2000 degrees, equivalent to J2000 15h 56m, -47d 20'), with a statistical uncertainty of 11.99 degrees. The angle from the Fermi LAT boresight is 69 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250502308/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250502308/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250502308/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/40327. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38355] GRB 250407A: VZLUSAT-2 detection
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40326 SUBJECT: GRB 250407A: VZLUSAT-2 detection DATE: 25/05/02 17:38:03 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU) -- the VZLUSAT-2/GRB payload collaboration. The long-duration GRB 250210A (Fermi/GBM detection: GCN 40104; SVOM/GRM detection: GCN 40120; Wind/Konus detection: GCN 40121; GRBAlpha detection: GCN 40237) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/). The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2025-04-07 15:48:20 UTC. The T90 duration is 9 s and the significance during T90 reaches 72 sigma (66 sigma) for detector unit no. 0 (no. 1). The light curve obtained by VZLUSAT-2 is available here: https://vzlusat2.konkoly.hu/static/share/GRB250407A_GCN_VZLUSAT2.pdf All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/ The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral. View this GCN Circular online at https://gcn.nasa.gov/circulars/40326. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38354] Fermi-LAT Gamma-ray Observations of IceCube-250429A
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40325 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-250429A DATE: 25/05/02 15:09:30 GMT FROM: chiara.bartolini-1(a)unitn.it C. Bartolini (University of Trento & INFN Bari), L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg), S. Garrappa (Weizmann Institute of Science) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC250429A neutrino event (GCN 40280) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2025-04-29 15:23:15.63 UTC (T0) with J2000 position RA = 59.68 (+0.47, -0.57) deg, Decl. = 25.32 (+0.39, -0.44) deg 90% PSF containment. No cataloged gamma-ray sources are found within the 90% IC250429A localization error (The Fourth Fermi-LAT catalog, 4FGL-DR4, The Fermi-LAT collaboration 2023, arXiv:2307.12546). We searched for the existence of intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5 sigma) new excess emission (> 100 MeV) within the IC250429A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC250429A best-fit position, the >100 MeV flux upper limit (95% confidence) is <2.17e-10 ph cm^-2 s^-1 for ~16-years (2008-08-04 / T0), <1.06e-08(<2.43e-07) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this region will continue. For this analysis, the Fermi-LAT contact person is C. Bartolini (chiara.bartolini at ba.infn.it). 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/40325. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38353] GRB 250502B: DDOTI Optical Observations
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40324 SUBJECT: GRB 250502B: DDOTI Optical Observations DATE: 25/05/02 15:03:40 GMT FROM: sahil.atri(a)students.uniroma2.eu Sahil Atri (U Roma), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observed the field of the GRB 250502B detected by Fermi/GBM (Fermi GBM Team, GCN 40314) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-05-02 UTC. DDOTI observed the Fermi/GBM error region (Fermi GBM Team, GCN Circ. 40314), covering about 80% of the error region. DDOTI observed from 10:35 UTC to 11:41 UTC (from T+0.4 h to T+1.5 h after the trigger) and obtained a total exposure of 26.4 minutes, alternating with other scientific programs. Comparing our observations to the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect no any uncatalogued source at the position reported by Fermi GBM Team, GCN Circ. 40314) down to a 10-sigma limiting AB magnitude of: w > 19.71. Nevertheless, by serendipity, the field observed included the position at RA= 20:58:11.46, DEC=+14:55:28.9, coincident with SN 2025ian/ATLAS25ebg (SN Ia) (https://www.wis-tns.org/object/2025ian/discovery-cert; Tonry et al., TNS Astronomical Transient Report No. 252299). We measured with w=17.91+/0.08 at T+10.1 days. These values are not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/40324. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38352] GRB 250430A: Swift-XRT refined Analysis
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40323 SUBJECT: GRB 250430A: Swift-XRT refined Analysis DATE: 25/05/02 13:27:07 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> R. Brivio (INAF-OAB), M. A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 1.4 ks of XRT data for GRB 250430A, from 166 s to 1.9 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=0.37 (+0.13, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.89 (+0.26, -0.24). The best-fitting absorption column is 1.7 (+0.9, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 9.6 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 3.8 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.7 (+0.9, -0.8) x 10^21 cm^-2 Galactic foreground: 9.6 x 10^20 cm^-2 Excess significance: 1.7 sigma Photon index: 1.89 (+0.26, -0.24) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01308754. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40323. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38351] GRB 250502A: Early optical counterpart detection by LCO.
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40322 SUBJECT: GRB 250502A: Early optical counterpart detection by LCO. DATE: 25/05/02 12:52:02 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 250502A triggered by the SVOM/ECLAIRs(Wang et al., GCN 40313) in the V, 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 May 02, 2025, starting 2.00 hours after the GRB trigger. We clearly detect the optical transient (OT) reported by GCNs (Rakotondrainibe et al., GCN 40315; An et al., GCN 40319, Li et al., GCN 40320) in our V, r band image. ------------------------------------------------------------------------------------------------------ |Date| |JD start| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude| ------------------------------------------------------------------------------------------------------ 2025-05-02 2460797.94930 2.00 1 x 600 V V = 19.08 +/- 0.04 2025-05-02 2460797.95500 2.15 1 x 600 r r = 19.02 +/- 0.04 ------------------------------------------------------------------------------------------------------ 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/40322. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38350] GRB 250430A: Swift/UVOT Detection
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40321 SUBJECT: GRB 250430A: Swift/UVOT Detection DATE: 25/05/02 12:22:02 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and T. M. Parsotan (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250430A 118 s after the BAT trigger (Parsotan et al., GCN Circ. 40292). The optical source detected in the UVOT white filter reported in that circular (and also detected by Oden & Guessoum, GCN Circ. 40295; Garnichy et al., GCN Circ. 40301; Komesh et al., GCN Circ. 40307; Zheng et al., GCN Circ. 40310 and Li et al., GCN Circ. 40311) was also detected in the UVOT U-band filter, but has since faded. 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_FC 141 291 147 19.08 ± 0.1 white 843 1856 264 19.40 ± 0.1 v 118 1733 169 >18.9 b 473 1831 156 >19.8 u 448 468 20 17.91 ± 0.3 u 621 1117 59 18.67 ± 0.3 w1 424 1782 156 >19.0 m2 1393 1413 19 >17.3 w2 696 1364 58 >18.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.092 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40321. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38349] GRB 250502A: SVOM/VT optical bump
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40320 SUBJECT: GRB 250502A: SVOM/VT optical bump DATE: 25/05/02 12:21:30 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), Y. Wang (PMO), R.Z. Li (YNAO), J.X. Cao (GXU), D.F. Kong (GXU) report on behalf of the SVOM/VT Instrument Center: GRB 250502A (sb25050205) (Wang et al., GCN 40313) was observed by on-board SVOM/VT after the automatic slew of the satellite. The VT conducted observations in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. With the downlinked X-band data, the optical counterpart (Rakotondrainibe et al., GCN 40315; An et al., GCN 40319) was observed with single exposure of 50 seconds in both VT_B and VT_R bands. The earliest observation started on 2025-05-02T08:51:36 UT (i.e. 334 seconds after the burst). The light curve shows a brightening with a peak brightness of 17.02+/-0.01 mag in VT_R and 17.86+/-0.02 mag at 584 seconds after the burst. The photometry is in the AB system and is not corrected for Galactic extinction. Given the color of VT_B-VT_R~0.8 mag, it might be a low or intermediate redshift GRB. Observation is ongoing. 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/40320. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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