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

[vsnet-grb-info 38216] GRB 250419A: Liverpool Telescope observations
by GCN Circulars 21 Apr '25

21 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40190 SUBJECT: GRB 250419A: Liverpool Telescope observations DATE: 25/04/21 10:19:17 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek and D. A. Perley (LJMU) report: We observed the SVOM-detected GRB250419a (Wang et al., GCN 40168) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 6x100s exposures in the SDSS r’ and i’ filters starting at 2025-04-20 21:43:22 UT, approximately 1.80 days after the trigger. We report a detection in both bands at the position of the optical counterpart (López et al., GCN 40169; Xin et al., GCN 40170; Zheng et al., GCN 40171; Kumar et al., GCN 40172; Thakur et al., GCN 40174; Lipunov et al., GCN 40179; Odeh et al., GCN 40180; Perley et al., GCN 40181; Pankov et al., GCN 40182; Pérez-Fournon GCN 40183; Kuin et al., GCN 40185; WU et al., GCN 40186; Xie et al., GCN 40187, Jiang et al., GCN 40188, Ghosh et al., GCN 40189). The obtained magnitudes are r = 20.61 ± 0.09 and i = 20.41 ± 0.08. The photometry was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction. MJD (mid) T_mid-T_0 Filter Mag. (AB) 60785.90925 43.33 h r 20.61 ± 0.09 60785.91782 43.54 h i 20.41 ± 0.08 View this GCN Circular online at https://gcn.nasa.gov/circulars/40190. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38215] GRB 250419A: LCO optical observation
by GCN Circulars 21 Apr '25

21 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40189 SUBJECT: GRB 250419A: LCO optical observation DATE: 25/04/21 08:35:46 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 250419A triggered by SVOM/ECLAIRs (Wang et al., GCN 40168) in V, r filters of the 1-meter Sinistro and B filter of 0.4 m SCICAM QHY600 telescopes at the Las Cumbres Observatory Global Telescope (LCOGT) node located at Siding Spring New South Wales, Australia. The 1-m Sinistro telescope is equipped with a 4K x 4K CCD (FOV: 26 x 26 arcmin, scale: 0.39 arcsec/pixel). 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 , starting from 2025-04-19T10:30:01.728 UT, 8.00 hours after the GRB trigger. Observation for later epochs are still going on. We clearly detect the optical transient (OT) reported by GCNs (López et al., GCN 40169; Xin et al., GCN 40170; Zheng et al., GCN 40171; Kumar et al., GCN 40172; Thakur et al., GCN 40174; Lipunov et al., GCN 40179; Odeh et al., GCN 40180; Perley et al., GCN 40181; Pankov et al., GCN 40182; Pérez-Fournon GCN 40183; Kuin et al., GCN 40185; WU et al., GCN 40186; Xie et al., GCN 40187, Jiang et al., GCN 40188) in our B, V, r band images. |Date| |UTstart| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude| ----------------------------------------------------------------------------------------------------- 2025-04-19 10:30:01.728 8.00 1 x 600 V V = 19.50+/- 0.02 2025-04-19 10:41:55.392 8.21 1 x 600 r r = 19.35+/- 0.01 2025-04-19 14:57:03.744 12.46 2 x 450 B B = 20.51 +/- 0.11 ----------------------------------------------------------------------------------------------------- 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/40189. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38214] GRB 250419A: JinShan optical observations
by GCN Circulars 21 Apr '25

21 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40188 SUBJECT: GRB 250419A: JinShan optical observations DATE: 25/04/21 07:08:51 GMT FROM: sqjiang at NAOC <sqjiang(a)bao.ac.cn> S.Q. Jiang (NAOC), S.Y. Fu (HUST), J. An, X. Liu, Z.P. Zhu, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of GRB 250419A detected by SVOM/ECLAIRs (Wang et al., GCN 40168), using the 100cm-C telescope (100C) of the JinShan project, located at Altay, Xinjiang, China. Observations started at 15:46:46.98 UT on 2025-04-20, i.e., 37.287 hr after the SVOM/ECLAIRs trigger, and a series of 600 s frames were obtained in the Sloan g-, r-, i- and z- bands. The optical afterglow (López et al., GCN 40169; Xin et al., GCN 40170; Zheng et al., GCN 40171; Kumar et al., GCN 40172; Thakur et al., GCN 40174; Lipunov et al., GCN 40179; Odeh et al., GCN 40180; Perley et al., GCN 40181; Pankov et al., GCN 40182; Pérez-Fournon GCN 40183; Kuin et al., GCN 40185; WU et al., GCN 40186; Xie et al., GCN 40187), which is consistent with the X-ray observed result (Page et al., GCN 40173 and GCN 40176), of GRB 250419A is clearly detected in our stacked images. Preliminary photometry results are as follows: T_mid(hr) Filter Mag(AB) MagErr 38.707 g 20.83 0.04 39.552 r 20.47 0.03 40.396 i 20.20 0.04 41.156 z 20.04 0.07 calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction. We acknowledge the excellent support from T.Q. Chen and Z.K. Feng for enabling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40188. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38213] GRB 250419A: SVOM/VT optical continuous observations
by GCN Circulars 21 Apr '25

21 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40187 SUBJECT: GRB 250419A: SVOM/VT optical continuous observations DATE: 25/04/21 05:15:24 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> W. J. Xie, L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, Z. H. Yao, Y. Xu, Y. N. Ma, X. H. Han, P. P. Zhang, J. Wang, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio (CEA), B.-T. Wang (YNAO, CAS), Y.H. Cheng (SWIFAR,YNU) reported on behalf of SVOM/VT team: Several ToO observations were performed by SVOM/VT for GRB 250419A (sb25041901, Wang et al., GCN 40168) in both VT_B (400nm-650nm) and VT_R (650nm-1000nm) band. The optical counterpart (Ocelotl López et al. GCN 40169, Xin et al. GCN 40170, Zheng et al. GCN 40171, Kumar et al. GCN 40172, Lipunov et al. GCN 40179, Odeh et al. GCN circ. 40180, Perley and Bochenek GCN circ. 40181, Pankov et al. GCN 40182, and Pérez-Fournon et al. GCN 40183, Kuin et al. GCN 40185, Wu et al. GCN 40186) was clearly detected in our observations. The observations show that a re-brightening phase arise during 16.0 to 24.0 hours post the trigger, followed by a short-term plateau and then a decay later. The latest magnitude of the optical counterpart detected by SVOM/VT are: MidTime (hours) | exposure time (s) | mag(AB) | mag err | band 48.133 | 28x60 | 20.388 | 0.08 | VT_R 48.103 | 26x60 | 20.924 | 0.07 | VT_B More follow-ups are encouraged. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40187. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38212] GRB 250419A: SVOM/C-GFT optical observations
by GCN Circulars 20 Apr '25

20 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40186 SUBJECT: GRB 250419A: SVOM/C-GFT optical observations DATE: 25/04/20 14:49:06 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> GRB 250419A: SVOM/C-GFT optical observations Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei, Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC), B.-T. Wang (YNAO, CAS), Y.H. Cheng (SWIFAR,YNU) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 250419A detected by SVOM/ECLAIRs (sb25041901, Wang et al., GCN 40168) with C-GFT. Our observations were started on 2025-04-19T13:08:53 UTC, ~10.66 hr after the trigger. The optical counterpart (reported by Ocelotl López et al. GCN 40169, Xin et al. GCN 40170, Zheng et al. GCN 40171, Kumar et al. GCN 40172, Lipunov et al. GCN 40179, Odeh et al. GCN circ. 40180, Perley and Bochenek GCN circ. 40181, Pankov et al. GCN 40182, and Pérez-Fournon et al. GCN 40183, Kuin et al. GCN 40185) was detected in the stacked g, r, and i-band images. The results are, (T-T0)_mid(sec) exptime(s) mag mag_err band ----------------------------------------------- 46935 10x30s 19.38 0.17 r 47723 10x30s 19.25 0.21 i 49013 10x30s 19.98 0.22 g The photometry was calibrated with nearby UCAC4 stars. Further analysis is on-going. We thank the observation assistants Shuai Liu and Chunlei Guo at Jilin observatory for their excellent support. Chinese Ground Follow-up Telescope of SVOM mission is located at Jilin, Changchun Observatory, National Astronomical Observatories, CAS. It has FOV of 1.28 deg x 1.28 deg with a 4k*4k CMOS detector mounted on the primary focus of 1.2-meter-aperure telescope. View this GCN Circular online at https://gcn.nasa.gov/circulars/40186. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38211] GRB 250409A: Swift/UVOT Follow up
by GCN Circulars 20 Apr '25

20 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40185 SUBJECT: GRB 250409A: Swift/UVOT Follow up DATE: 25/04/20 12:39:57 GMT FROM: Paul Kuin at MSSL <npkuin(a)gmail.com> Paul Kuin (MSSL/UCL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began observations of the field of SVOM detected GRB 250419A/(SVOM burst-id sb25041901) 3790s after the SVOM ECLAIR trigger at 2025-04-19T02:29:32 (Wang et al., GCN Circ. 40168). A source consistent with the position reported by Kin Ocelotl López et al. (Colibri - GCN Circ. 40169) and Liping Xin at al. (SVOM-VT GCN Circ 40170), also reported by Weikang Zheng et al. (KAIT - GCN Circ. 40171) and Amit Kumar et al. (GCN Circ. 40172) has been detected in the initial UVOT exposures. The detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) Exp(s) Mag (Vega) u 3790 1667 17.73 +/- 0.04 u 9323 259 18.19 +/- 0.10 u 48658 1206 19.64 +/- 0.14 u 54296 1028 19.52 +/- 0.13 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.085 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40185. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38210] GRB 250416C / EP250416a: SVOM/GRM observation of a burst
by GCN Circulars 20 Apr '25

20 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40184 SUBJECT: GRB 250416C / EP250416a: SVOM/GRM observation of a burst DATE: 25/04/20 12:06:30 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Maria-Grazia Bernardini (INAF-OAB), Stéphane Schanne (CEA), Frédéric Piron (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by GRB 250416C at 2025-04-16T17:53:48 (T0). This burst was also detected by Konus-Wind (D. Svinkin et al, GCN 40167) and EP (Zhao et al., GCN 40154; Zhou et al., GCN 40165). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 8 +4/-4 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250416C.png The time coincidence and relative counts of each detectors of GRM suggest that this GRB is associated with EP250416a. In addition, the position of this burst, which is determined by EP/FXT (GCN 40154, RA: 256.4228 deg, DEC: 25.7755 deg, Error: 20 arcsec), located at about 83 degrees from the SVOM optical axis, and was outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-10 to T0+10 s is best fitted by a power law function. The power law index is -2.04 +0.19/-0.26. The event fluence (10-1000 keV) in this time interval is (1.2 +0.3/-0.3)E-06 erg/cm^2. 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Chen-Wei Wang (IHEP) (cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/40184. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38209] GRB 250419A: LCO optical afterglow multi-band observations
by GCN Circulars 20 Apr '25

20 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40183 SUBJECT: GRB 250419A: LCO optical afterglow multi-band observations DATE: 25/04/20 11:35:44 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> I. Pérez-Fournon, F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz, I. Correa-Plasencia (ULL), and A. López-Oramas (IAC and ULL) Following the detection of the Gamma-Ray Burst GRB 250419A by SVOM/ECLAIRs (Wang et al., GCN circ. 40168) and of the X-ray afterglow by Swift-XRT (Page et al., GCN circ. 40173), we observed the GRB field with the two Las Cumbres Observatory Global Telescope network (LCOGT) 1-m telescopes, equipped with Sinistro cameras, located at the LCOGT node at Siding Spring Observatory (Australia) in the SDSS u, g, r, and i filters. The observations started at 2025-04-19 11:20:00 UTC, about 8.84 hours after the SVOM trigger, with simultaneous observations in the r and i filters followed by simultaneous observations in the u and g filters. An uncatalogued source is detected in the four filters at the position of the optical afterglow reported first by Ocelotl López et al. (GCN circ. 40169), that is consistent with the Swift-XRT position (Page et al., GCN circ. 40176) and with other optical detections reported by Xin et al. (GCN circ. 40170), Zheng et al. (GCN circ. 40171), Kumar et al. (GCN circ. 40172), Thakur et al. (GRB redshift of z = 0.845, GCN circ. 40174), Lipunov et al. (GCN circ. 40179), Odeh et al. (GCN circ. 40180), Perley and Bochenek (GCN circ. 40181), and Pankov et al. (GCN circ. 40182). We measure the following magnitudes, calibrated against SDSS DR16 (Ahumada et al. 2020, ApJS, 249, 3A) stars, that are not corrected for Galactic extinction: Date | UT start | mag | error | filter | exposure time (sec) | ------------------------------------------------------------------------ 2025-04-19 11:20:00 19.15 0.07 i 300 2025-04-19 11:20:03 19.40 0.06 r 300 2025-04-19 11:45:15 20.13 0.17 u 300 2025-04-19 11:45:32 19.76 0.09 g 300 This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2025A-009, SGLF). View this GCN Circular online at https://gcn.nasa.gov/circulars/40183. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38208] GRB 250419A: Mondy and AbAO Optical Observations
by GCN Circulars 20 Apr '25

20 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40182 SUBJECT: GRB 250419A: Mondy and AbAO Optical Observations DATE: 25/04/20 10:26:54 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO) report on behalf of IKI-GRB-FuN: We observed the field of a soft long GRB 250419A detected by far by SVOM (Wang et al., GCN 40168), and Swift (Page et al., GCN 40111; Page et al., GCN 40176) at the redshhift of z = 0.845 (Thakur et al., GCN 40174) with the 1.5-meter AZT-33IK telescope of the Sayan Solar Observatory (Mondy), and the 0.7-meter AS-32 telescope of the Abastumani Astrophysical Observatory (AbAO). The R-band observations began on 2025-04-19 at 15:21:16 UT, i.e. ~0.55 days since trigger at Mondy. The optical counterpart (López et al., GCN 40169; Xin et al., GCN 40170; Zheng et al., GCN 40171; Kumar et al., GCN 40172; Thakur et al., GCN 40174; Lipunov et al., GCN 40179; Odeh et al., GCN 40180; Perley & Bochenek, GCN 40181) is detected in the stacked image from both telescopes. The preliminary photometry is as follows: Date UTstart Exptime t-T0 Filter OT Err UL Telescope (s) (mid, days) (3sigma) 2025-04-19 15:21:16 21*120 0.55052 R 19.68 0.05 22.2 AZT-33IK 2025-04-19 17:15:36 76*60 0.64172 R 19.72 0.25 20.2 AS-32 Ref. stars USNO-B1.0 RA Dec R2 202.4329 7.0165 15.18 202.3871 7.0378 16.79 The photometry is based on nearby USNO-B1.0 stars (R2 magnitudes) and has not been corrected for the Galactic extinction View this GCN Circular online at https://gcn.nasa.gov/circulars/40182. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38207] GRB 250419A: Liverpool Telescope observations
by GCN Circulars 20 Apr '25

20 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40181 SUBJECT: GRB 250419A: Liverpool Telescope observations DATE: 25/04/20 07:27:45 GMT FROM: Daniel Perley at Liverpool JMU <d.a.perley(a)ljmu.ac.uk> D. A. Perley and A. Bochenek (LJMU) report: We obtained imaging observations of the SVOM-detected GRB250419A (Wang et al., GCN 40168) with IO:O on the Liverpool Telescope on the night of 2025-04-19 between 22:02 and 22:26 UT. 6x100s exposures were acquired in both SDSS r-band and SDSS i-band. We clearly detect the optical counterpart (e.g. Ocelotl López et al., GCN 40169; Xin et al., GCN 40170) at the following magnitudes, calibrated using PanSTARRS secondary standards: MJD dt filter mag +/- unc 60784.91810 0.814 r 19.96 +/- 0.06 60784.92664 0.822 i 19.76 +/- 0.06 View this GCN Circular online at https://gcn.nasa.gov/circulars/40181. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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