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

[vsnet-grb-info 37466] GRB 250222A: SVOM/GRM observation of a burst
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39454 SUBJECT: GRB 250222A: SVOM/GRM observation of a burst DATE: 25/02/24 13:15:04 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: Frédéric Piron (LUPM), Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia, Sébastien Guillot (IRAP) report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a long burst GRB 250222A (SVOM trigger reference: sb25022201) at 2025-02-22T14:24:26.100 UTC (T0). With the event-by-event data downloaded through the X-band ground station, the GRM light curve of 15 to 600 keV shows that this burst consists of multi-pulses with a T90 of 4.3 +0.6/-0.5 s. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250222A.png The SVOM/GRM on-ground localization of this burst is (J2000): RA: 284.2 deg DEC: -61.0 deg Error: 1.6 deg (1sigma, statistical only) We caution that the calibration of SVOM/GRM is undergoing and this localization is subject to systematic errors. In addition, this burst was detected by the Count-Rate Trigger onboard ECLAIRs, as an increase in counts over background, but it was not localized by the coded-mask imaging process, which confirms that the burst occurred outside the ECLAIRs field of view. 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/39454. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37465] EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39453 SUBJECT: EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading DATE: 25/02/24 13:00:21 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Jean-Grégoire Ducoin (CPPM), Francesco Magnani (CPPM), Benjamin Schneider (LAM), Alan M. Watson (UNAM), Kin Ocelotl López (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Diego López-Cámara (UNAM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of EP250223a (Lian et al., GCN Circ. 39429), detected also by Swift/XRT (Kennea et al., GCN Circ. 39437), with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-02-24 04:59 to 07:19 UTC (13.9 to 16.3 hours after the trigger) and obtained 96 minutes of exposure in the r filter. The data were coadded with the COLIBRÍ pipeline and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our photometry is in the AB system and is not corrected for Galactic extinction. In a stacked image of our first 50 minutes of exposure, we detect a source at the position of the optical afterglow candidate reported by Hauptmann et al. (GCN Circ. 39436) and many other groups (GCN Circs. 39439, 39440, 39441, 39445, 39447, and 39449) with magnitude: r = 19.87 +/- 0.01 Comparing our r magnitude to the similar ones reported by Hauptmann et al. (GCN Circ. 39436) and Pérez-Fournon et al. (GCN Circ. 39440), we see no more than slow fading between about 6 and 15 hours. We encourage continued monitoring of this source. 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/39453. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37464] GRB 250210A: VZLUSAT-2 detection
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39452 SUBJECT: GRB 250210A: VZLUSAT-2 detection DATE: 25/02/24 12:50:48 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: GCN Circular 39262; AstroSat/CZTI: GCN Circular 39267; INTEGRAL/SPI-ACS: CGN Circular 39268; SVOM/GRM: CGN Circular 39282; GRBAlpha detection: GCN 39313) was detected by the GRB detector on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/). The data acquisition was performed by the GRB detector unit no. 0. The detection was confirmed at the peak time 2025-02-10 05:31:59 UTC. The T90 duration is 49 s and the significance during T90 reaches 10 sigma. The light curve obtained by VZLUSAT-2 is available here: https://vzlusat2.konkoly.hu/static/share/GRB250210A_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/39452. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37463] GRB 250206A: VZLUSAT-2 detection
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39451 SUBJECT: GRB 250206A: VZLUSAT-2 detection DATE: 25/02/24 12:41:13 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 250206A (Fermi/GBM detection: GCN 39172; Fermi/LAT detection: GCN 39233; EIRSAT-1/GMOD detection: GCN 39236; Konus/Wind detection: GCN 39283; INTEGRAL/SPI-ACS peak detection at 2025-02-06 ~19:51:45 UTC) 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 2025-02-06 19:51:43 (19:51:46) UTC. The T90 duration is 67 s (63 s) and the significance during T90 reaches 11 sigma (17 sigma) for detector unit no. 0 (no. 1). The light curve obtained by VZLUSAT-2 is available here: https://vzlusat2.konkoly.hu/static/share/GRB250206A_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/39451. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37462] EP250223a: REM NIR upper limit
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39450 SUBJECT: EP250223a: REM NIR upper limit DATE: 25/02/24 11:40:05 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of EP250223a (Lian et al., GCN 39429; Wang et al., GCN 39448), also detected by Swift/XRT (Kennea et al., GCN 39437) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the J, H, and K bands, started on 2025 February 24 at 01:29:31 UT (i.e. 10.4 hr after the burst), and lasted for about 1 hour. From preliminary inspection, we do not find any counterpart at the position of the reported optical afterglow (Hauptmann et al., GCN 39436; Levan et al., GCN 39438; Wu et al., GCN 39439; Pérez-Fournon et al., GCN 39440; Izzo & Malesani, GCN 39441; Xin et al., GCN 39445; Guo et al., GCN 39447; An et al., GCN 39449) down to the following 3sigma limit: H > 17.6 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 10.85 hours after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/39450. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37461] EP250223a: TRT optical afterglow observation
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39449 SUBJECT: EP250223a: TRT optical afterglow observation DATE: 25/02/24 11:34:23 GMT FROM: sqjiang at NAOC <sqjiang(a)bao.ac.cn> J. An, S.Q. Jiang, N.C. Sun (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), Z. Fan, W.X. Li, Y.N. Wang, D. Xu (NAOC) report on behalf of a large collaboration: We observed the field of EP250223a detected by EP (Lian et al., GCN 39429; Wang et al., GCN 39448), and observed by Swift/XRT (Kennea et al., GCN 39437), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Cerro Tololo Inter-American Observatory, Chile. Observations started at 00:37:15.66 UTC on 2025-02-24, i.e., 9.544 hrs after the EP trigger, and a series of 200 s frames were obtained in B, V, R and I bands. The optical afterglow (Wu et al., GCN 39439; Guo et al., GCN 39447; Izzo et al., GCN 39441; Xin et al., GCN 39445; Pérez-Fournon et al., GCN 39440; Hauptmann et al., GCN 39436; Levan et al., GCN 39438) is clearly detected in our stacked images with: | T (mid) - T0 (hours)| band | mag | error | | 9.816 | B | 21.32 | 0.14 | | 9.996 | V | 20.17 | 0.07 | | 10.176 | R | 19.86 | 0.07 | | 10.356 | I | 19.41 | 0.12 | calibrated with Panstarrs-DR2 stars in the field and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39449. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37460] EP250223a: refined analysis of the EP-WXT and FXT observations
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39448 SUBJECT: EP250223a: refined analysis of the EP-WXT and FXT observations DATE: 25/02/24 10:08:07 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. Wang (PMO, CAS), T. Y. Lian, W. J. Zhang (NAOC, CAS), X. Tian (GXU), R. Z. Li(YNAO, CAS), H. W. Pan (NAOC, CAS) report on behalf of the Einstein Probe team: The X-ray transient EP250223a triggered the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Lian et al., GCN 39429), and followed by the Swift XRT (Kennea et al., GCN 39437) and several optical telescopes (Levan et al., GCN 39436, Wu et al., GCN 39439, Pérez-Fournon et al., GCN 39440, Izzo et al., GCN 39441, Xin et al., GCN 39445) at the redshift of 2.756 (Levan et al., GCN 39438). The refined analysis of the WXT data shows that the event started at 2025-02-23T15:02:05.66 (UTC) and lasted for 140 s with the peak flux of 2 x 10^(-9) erg/s/cm^2, before the observation was interrupted by the autonomous follow-up observation. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic equivalent hydrogen column density of 1.36 x 10^21 cm^-2 and a photon index of 2.1 (-/+0.6). The derived average unabsorbed 0.5-4 keV flux is 4.4 (-1.1/+1.4) x 10^(-10) erg/s/cm^2. The autonomous observation by the Follow-up X-ray Telescope (FXT) was performed about two minutes later. The on-ground analysis shows that an uncatalogued source was detected at R.A. = 98.2748, DEC = -22.4443 (J2000) with an uncertainty of about 10 arcsec (radius, 90% C.L. statistical and systematic). The average FXT 0.5-10 keV spectrum can be fitted with an absorbed power law with a Galactic equivalent hydrogen column density of 1.36 x 10^21 cm^-2 and a photon index of 1.97 (-/+0.05). The derived average unabsorbed 0.5-10 keV flux is 2.5 (-/+0.1) x 10^(-11) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. Further follow-up observations with EP-FXT have been scheduled. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/39448. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37459] EP250223a: 1.6m Mephisto and 50cm array observations
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39447 SUBJECT: EP250223a: 1.6m Mephisto and 50cm array observations DATE: 25/02/24 10:02:52 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Helong Guo, Guowang Du, Yu Pan, Xinlei Chen, Brajesh Kumar, Xiaotong Chen, Yiheng Xie, Yuan Fang, Xingzhu Zou, Yuanpei Yang, Jinghua Zhang, Dezi Liu, Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team: The field of EP250223a detected by EP Team (Lian et al., GCN 39429) was observed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) and 50cm array facilities of Yunnan University located at Lijiang Observatory. Simultaneous uvgr band images with different exposure times were acquired with Mephisto starting from 15:20:12 2025-02-23 UT (~15.6 minutes after the trigger) and with 50cm array in iz bands starting from 15:49:08 2025-02-23 UT (~44.5 minutes after the trigger). The afterglow candidate (Lipunov et al., GCN 39434; Hauptmann et al., GCN 39436; Kennea et al., GCN 39437; Levan et al., GCN 39438; Wu et al., GCN 39439; Pérez-Fournon et al., GCN 39440; Izzo et al., GCN 39441; Xin et al., GCN 39445) is clearly detected in each v, g, r band and in the stacked u band images taken with Mephisto. The candidate is also visible in the stacked i band image of 50 cm array but not in the stacked z band. The preliminary magnitudes and 3-sigma upper limit are below: 1.6m Mephisto Start_Time(UT) | Band | Exp(s) | Mag/LimMag(AB) --------------------|------|--------|---------------- 2025-02-23T16:00:53 | u | 300*3 | 20.97 +/- 0.29 2025-02-23T15:25:14 | v | 180 | 19.93 +/- 0.22 2025-02-23T15:20:12 | g | 10 | 18.11 +/- 0.12 2025-02-23T15:25:14 | r | 50 | 18.17 +/- 0.07 50CM array Start_Time(UT) | Band | Exp(s) | Mag/LimMag(AB) --------------------|------|--------|--------------- 2025-02-23T15:49:08 | i | 300*3 | 18.89 +/- 0.11 2025-02-23T15:49:08 | z | 300*3 | >18.81 ------------------------------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m 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. The 50cm array consists of two 50cm telescopes for wide-field surveys and also serves as the supporting facility for monitoring the Mephisto detected targets. ------------------------------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/39447. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37458] GRB 250221A: TNOT detection of the optical counterpart
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39446 SUBJECT: GRB 250221A: TNOT detection of the optical counterpart DATE: 25/02/24 09:24:45 GMT FROM: Xiaofeng Wang at Tsinghua University <wang_xf(a)mail.tsinghua.edu.cn> A. Iskandar（XAO), H.-C. Zhu (THU)，X.-F. Wang, and L.-T. Wang (XAO) report the optical detection of the afterglow of GRB 250221A (Francile et al., GCN 39395; Caputo et al., GCN 39396; Watson et al., GCN 39397; Melandri et al., GCN 39406; Shilling et al., GCN 39409; Guo et al., GCN 39412; Muenter et al., GCN 39417; Palmerio et al., GCN 39418; Pankov et al., GCNs 39422,39424,39426,39427; Ghosh et al., GCN 39425). We obtained the r-band images (~2.40 days after the burst) with the 80~cm Tsinghua-Nanshan Optical Telescope (TNOT) located at Nanshan Station of Xinjiang Astronomy Observatory, starting on 2025-02-23 (UT) 13:05:49. The afterglow is clearly detected on the stacked images, with the following magnitude: r = 20.46 +- 0.17 mag (MJD =60698.5457) The above photometric result is calibrated against the Pan-STARRS catalog without a correction for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39446. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37457] EP250223a: SVOM/VT optical observation
by GCN Circulars 24 Feb '25

24 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39445 SUBJECT: EP250223a: SVOM/VT optical observation DATE: 25/02/24 07:51:36 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> L.P. Xin, Y.L. Qiu(NAOC), Y. Wang(PMO),H.L. Li, C. Wu, Z.H. Yao, Y. N. Ma, X.H. Han, H.B. Cai, J. Wang, Y. Xu, J.Y. Wei(NAOC), J. T. Palmerio(CEA/Irfu) report on behalf of the SVOM team: The SVOM/VT conducted a ToO follow-up observations of the EP250223a (Lian et al., GCN 39429) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. The afterglow(Benjamin et al., GCN 39436) was clearly detected within the errorbox of EP/FXT (Lian et al., GCN 39429) in VT_R and VT_B images. The afterglow was fading during our observations and the brightness was estimated to be 19.21+/-0.05 mag in AB magnitude in VT_R, and 20.11+/-0.05 mag in AB magnitude in VT_B, at the mid time of 3.7 hours post the burst. 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/39445. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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