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

[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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[vsnet-grb-info 38348] GRB 250502A: TRT optical afterglow confirmation
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40319 SUBJECT: GRB 250502A: TRT optical afterglow confirmation DATE: 25/05/02 12:05:04 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> J. An (NAOC), K. Noysena, S. Tinyanont, K. Chanchaiworawit (NARIT), S.Y. Fu (HUST), X. Liu, Z.P. Zhu, S.Q. Jiang, D. Xu (NAOC) report on behalf of a large collaboration: We observed the field of GRB 250502A detected by SVOM/ECLAIRs (Wang et al., GCN 40313), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at New South Wales, Australia (SBO). Observations started at 10:30:05 UTC on 2025-05-02, i.e., ~1.73 hr after the SVOM trigger and a series of frames in the B/V/R/I bands were obtained. The optical afterglow of the burst (Rakotondrainibe et al., GCN 40315) is clearly detected in our individual images. Preliminary photometry shows that the afterglow has decayed to I ~ 18.6 mag at 2.00 hr post-trigger, calibrated with Pan-STARRS DR2 catalog and not corrected for Galactic extinction. Observations are ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/40319. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38347] GRB 250430A: Enhanced Swift-XRT position
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40318 SUBJECT: GRB 250430A: Enhanced Swift-XRT position DATE: 25/05/02 11:57:52 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1722 s of XRT Photon Counting mode data and 2 UVOT images for GRB 250430A, 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 = 233.38699, -18.11851 which is equivalent to: RA (J2000): 15h 33m 32.88s Dec (J2000): -18d 07' 06.6" with an uncertainty of 2.3 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/40318. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38346] Fermi GRB 250502B: Global MASTER-Net observations report
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40317 SUBJECT: Fermi GRB 250502B: Global MASTER-Net observations report DATE: 25/05/02 11:31:09 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-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 GRB 250502B ( Fermi GBM team, GCN 40314) errorbox 74 sec after notice time and 110 sec after trigger time at 2025-05-02 10:15:44 UT, with upper limit up to 18.4 mag. Observations started at twilight. The observations began at zenith distance = 44 deg. The sun altitude is -11.2 deg. The galactic latitude b = -18 deg., longitude l = 61 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2858681 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 121 | 2025-05-02 10:15:44 | MASTER-OAFA | (20h 40m 38.20s , +13d 02m 12.4s) | C | 20 | 17.2 | 121 | 2025-05-02 10:15:44 | MASTER-OAFA | (20h 49m 58.93s , +13d 25m 00.9s) | C | 20 | 18.3 | 155 | 2025-05-02 10:16:23 | MASTER-OAFA | (20h 40m 37.90s , +13d 02m 09.6s) | C | 10 | 16.9 | 166 | 2025-05-02 10:16:23 | MASTER-OAFA | (20h 49m 58.55s , +13d 24m 57.5s) | C | 30 | 18.4 | 205 | 2025-05-02 10:17:07 | MASTER-OAFA | (20h 43m 52.56s , +13d 09m 28.3s) | C | 20 | 17.2 | 215 | 2025-05-02 10:17:08 | MASTER-OAFA | (20h 53m 13.53s , +13d 32m 15.9s) | C | 40 | 18.4 | 256 | 2025-05-02 10:17:54 | MASTER-OAFA | (20h 43m 52.15s , +13d 09m 25.1s) | C | 30 | 17.2 | 266 | 2025-05-02 10:17:54 | MASTER-OAFA | (20h 53m 13.16s , +13d 32m 11.9s) | C | 50 | 18.3 | 317 | 2025-05-02 10:18:50 | MASTER-OAFA | (20h 43m 51.68s , +13d 09m 20.3s) | C | 40 | 17.2 | 328 | 2025-05-02 10:18:50 | MASTER-OAFA | (20h 53m 12.71s , +13d 32m 06.8s) | C | 60 | 18.2 | 388 | 2025-05-02 10:19:56 | MASTER-OAFA | (20h 43m 51.16s , +13d 09m 15.6s) | C | 50 | 17.1 | 399 | 2025-05-02 10:19:56 | MASTER-OAFA | (20h 53m 12.22s , +13d 32m 01.2s) | C | 70 | 18.0 | 474 | 2025-05-02 10:21:12 | MASTER-OAFA | (20h 43m 50.52s , +13d 09m 08.5s) | C | 70 | 17.0 | 581 | 2025-05-02 10:22:48 | MASTER-OAFA | (20h 43m 49.65s , +13d 08m 59.4s) | C | 90 | 16.8 | 715 | 2025-05-02 10:24:52 | MASTER-OAFA | (20h 39m 05.67s , +13d 52m 50.6s) | C | 110 | 16.6 | 828 | 2025-05-02 10:27:21 | MASTER-OAFA | (20h 36m 00.38s , +11d 56m 35.1s) | C | 40 | 16.4 | 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/40317. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38345] GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40316 SUBJECT: GRB 250430A: Optical Observations via Virtual Telescope Project, Italy DATE: 25/05/02 11:22:42 GMT FROM: Gianluca Masi at Virtual Telescope Project <gianluca(a)bellatrixobservatory.org> Gianluca Masi, Virtual Telescope Project (Italy), reports: We attempted to observe the optical counterpart (Parsotan et al., GCN 40292; Odeh et al., GCN 40295) of GRB 250430A with the 14” robotic unit available at the Virtual Telescope Project facility in Manciano, Italy, equipped with a KAF-3200E based CCD camera, its QE peaking (90%) in the red part of the spectrum. We collected 7, 300-second unfiltered exposures, then we averaged them. The central time of the resulting stack was 30 April, 22:19 UTC, that is about 4.75 hours after the burst. We detected a faint object at the following position (J2000.0): RA: 15 33 32.94s Decl.: -18 07 06.5 R= 20.8 (assuming R-mags from Gaia DR2 for the reference stars). This position is consistent with Odeh et al., GCN 40295. At the position above, there is a very faint source on Panstarrs DR1 images, as well as on DESI Legacy DR10 images (the latter mentioned by Garnichey et al., GCN 40301), likely the host galaxy of GRB 250430A. The image is available here: https://www.virtualtelescope.eu/2025/05/02/grb-250430a-detection-of-the-opt… View this GCN Circular online at https://gcn.nasa.gov/circulars/40316. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38344] GRB 250205A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40315 SUBJECT: GRB 250205A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate DATE: 25/05/02 10:25:06 GMT FROM: Ny Avo Rakotondrainibe at LAM <nyavo.rakotobe(a)gmail.com> Ny Avo Rakotondrainibe (LAM), Enrique Moreno Méndez (UNAM), Jean-Grégoire Ducoin (CPPM), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), 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), Margarita Pereyra (UNAM), Antonio de Ugarte Postigo (LAM) and Y. Wang (PMO, CAS) report: We imaged the field of the SVOM/ECLAIRs GRB 250205A (sb25050205) with the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-05-02 08:58 UTC to 09:17 UTC (682 to 1848 seconds after the trigger) and obtained 16 minutes of exposure in the i filter. The data were coadded with the COLIBRÍ pipeline and analyzed in STDWeb/STDPipe (Karpov 2025), with photometric calibration against Pan-STARRS DR1. Our photometry is in the AB system and is not corrected for Galactic extinction. Within the SVOM/ECLAIRs error box, we detect a bright uncatalogued source at: RA (J2000) = 13:46:05.60 = 206.5233d Dec (J2000) = -10:45:31.9 = -10.7588d The preliminary magnitude derived for that source is: i = 17.41 +/- 0.03 Further observations are planned. We warmly thank the COLIBRÍ and DDRAGO engineering teams and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/40315. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38343] GRB 250502B: Fermi GBM Final Real-time Localization
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40314 SUBJECT: GRB 250502B: Fermi GBM Final Real-time Localization DATE: 25/05/02 10:24:22 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 10:13:53 UT on 2 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250502B (trigger 767873638.16821 / 250502426). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 312.3, Dec = 14.5 (J2000 degrees, equivalent to J2000 20h 49m, 14d 30'), with a statistical uncertainty of 2.3 degrees. The angle from the Fermi LAT boresight is 56.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250502426/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250502426/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250502426/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40314. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38342] GRB 250502A: SVOM detection of a burst
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40313 SUBJECT: GRB 250502A: SVOM detection of a burst DATE: 25/05/02 09:51:06 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Y. Wang (PMO, CAS), J.X Cao (GXU), L. Bouchet, M. Brunet (IRAP), C. Plasse (CEA) on behalf of the SVOM mission team. SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250502A (SVOM burst-id sb25050205) starting at 2025-05-02T08:46:27 UTC (Tb) The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected by the Image Trigger (IMT). A sequence of 3 alerts was produced. IMT provided the alert with the best signal-to-noise-ratio (SNR) of 8.94 in the 8-50 keV energy band over a time window of 40.96 seconds starting at Tb. The localization of the best alert is R.A., Dec. 206.479, -10.643 degrees: R.A. (J2000) = 13h45m54.84s Dec. (J2000) = -10h38m34.49a with a 90% confidence level (C.L.) radius of 8.84 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. MXT began observing the field after the slew. The analysis of MXT data will be published in a future circular. VT began observing the field after the slew. The analysis of the recorded images will be published in a future circular gathering information on the follow-up of the SVOM optical instruments. 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/40313. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38341] GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
by GCN Circulars 02 May '25

02 May '25

TITLE: GCN CIRCULAR NUMBER: 40312 SUBJECT: GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit DATE: 25/05/02 06:35:58 GMT FROM: Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, Messina, Italy <giovannicalapai(a)tiscali.it> Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, (Messina) Italy Member of: GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. Report: We imaged the field of GRB 250430A detected by Swift/BAT (Parsotan et al. GCN 40292), with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3. The observations were started at 2025-04-30 21:32 UT (approximately 4.02 hours after burst) stacking a set of unfiltered CCD image. We co-added 80 exposures of 60 sec each. Start T0+ End T0+ CR lim 4.02 hour 6.85 hour 19.9 We did not found any optical uncatalogued object within the Swift error circle. Magnitudes were estimated with the PanSTARRS cat. and are not corrected for galactic dust extinction. Our upper limit is consistent with other observations reported by Kawabata et al. (GCN 40294), Odeh et al. (GCN 40295), Saccardi et al. (GCN 40301), Hagio et al. (GCN 40302), Quadri et al. (GCN 40303), Moretti et al. (GCN 40304), Atri et al. (GCN 40305), Komesh et al. (GCN 40307), Mo et al. (GCN 40308), Zheng et al. (GCN 40310), Li et al. (GCN 40311). The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40312. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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