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[vsnet-grb-info 43606] EP260806a: WFST optical observations
by GCN Circulars 15 Aug '26

15 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45385 SUBJECT: EP260806a: WFST optical observations DATE: 26/08/15 07:23:12 GMT FROM: ylhua(a)pmo.ac.cn Yan-Long Hua, Jin-Jun Geng, Tian-Rui Sun, Ye Li, Yi-Fang Liang, Yuan-Tai Yang, Ji-An Jiang, Zhi-Ping Jin and Xue-Feng Wu report on behalf of the WFST team: Following the detection of EP260806a by Einstein Probe (Li et al., GCN 45299), we performed follow-up observations using the Wide Field Survey Telescope (WFST Collaboration; arXiv:2306.07590) at the Lenghu Astronomical Observation Base in Qinghai Province, China. Observations in the g-band began at 2026-08-14T15:55:51 UTC, approximately 184.89 hours after the trigger. The optical candidate reported by LCO (Ducoin et al., GCN 45300) and COLIBRÍ (Antonio et al., GCN 45306) was detected as the optical counterpart. We performed image subtraction on the stacked images using PanSTARS templates and detected the optical counterpart (He et al., GCN 45300; de Ugarte Postigo et al., GCN 45302) in both bands. No other sources are detected within the EP/FXT error region (Li et al., GCN 45299). The preliminary measurements are given in AB magnitudes and are not corrected for Galactic extinction: g = 18.312 ± 0.008 (AB) We thank the WFST staff for supporting these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/45385. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43605] The EP-WXT trigger 01709280562 is likely a flaring star
by GCN Circulars 15 Aug '26

15 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45384 SUBJECT: The EP-WXT trigger 01709280562 is likely a flaring star DATE: 26/08/15 01:32:54 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.-H. I. Yin (HKU), Z.-C. Zou (NJU), J. H. Wu (GZHU), Y. Q. Zhao (PRIC, USTC), Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709280562 at the time of 2026-08-14T19:52:10, is likely a stellar flare associated with UPM J0042-5444. The estimated flux of the flare is around 1.0 x 10^-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 2.3 x 10^31 erg/s. 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/45384. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43604] GRB 260808B: Liverpool Telescope further optical observations
by GCN Circulars 14 Aug '26

14 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45380 SUBJECT: GRB 260808B: Liverpool Telescope further optical observations DATE: 26/08/14 11:46:15 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek, D. A. Perley (LJMU), report: We observed the field of GRB 260808B (Bouchet et al., GCN 45316) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 8x120s exposures in SDSS griz filters, starting at 2026-08-13 01:30:02 UT, approximately 4.5 days after SVOM/ECLAIRS trigger. We detect a source in the stacked images, with the photometry given below, at the counterpart position reported by Turpin et al. (GCN 45318), Li et al. (GCN 45320), also observed by Wang et al. (GCN 45322), Adami et al. (GCN 45323), Saccardi et al. (GCN 45328), Schneider et al. (GCN 45329), Bochenek et al., (GCN 45330), with re-brightening reported by Li et al. (GCN 45359) and Guelfand et al. (GCN 45364). MJD (mid) T_mid-T_0 Filter Mag. (AB) 61265.06782 4.47 d g 22.19 ± 0.09 61265.08202 4.48 d r 21.77 ± 0.06 The photometry is in the AB magnitude system, was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/45380. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43603] EP260812b: Optical upper limit with Kinder
by GCN Circulars 14 Aug '26

14 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45383 SUBJECT: EP260812b: Optical upper limit with Kinder DATE: 26/08/14 14:33:12 GMT FROM: Janet Chen at National Central University <janetstars(a)gmail.com> Y.-H. Lee, A. Aryan, T.-W. Chen, C.-S. Lin (all NCU), A. K. H. Kong (NTHU), S. J. Smartt, J. Gillanders (both Oxford), S. Yang(HNAS), A. Sankar.K, K. N.-T. Ho, A. Dutta, M.-H. Lee, Y.-C. Pan, C.-C. Ngeow, C.-H. Lai, H.-C. Lin, H.-Y. Hsiao, W.-J. Hou, J.-K. Guo (all NCU), Z. N. Wang, D. C. Qiang, L. L. Fan (all HNAS), Y. J. Yang (NYUAD), H.-W. Lin (UMich), K. W. Smith, H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, C. Angus, A. Aamer (all QUB), T. Moore (STScI), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP260812b (Li et al., GCN 45368) using the 1m LOT at the Lulin observatory, as part of the Kinder collaboration (Chen et al. 2025, ApJ, 983, 86, doi:10.3847/1538-4357/adb428). The first LOT epoch of observations in r-band started at 18:18 UTC on the 13th of August 2026 (MJD 61265.7625), 18.71 hr after the EP-WXT detection. We utilized the astroalign (Beroiz et al. 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al. 2022, ApJ, 935, 167) packages to align and stack the individual frames. In the stacked image, we did not detect the optical counterpart reported by Malesani et al., (GCN 45367); Ma et al., (GCN 45370); Gill et al., (GCN 45371); Starling et al., (GCN 45374) and Eyles-Ferris et al., (GCN 45026). Moreover, we further used AutoPhOT to perform PSF photometry. The details of the observations and the measured 3-sigma upper limit (in the AB system) are as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass LOT | r | 61265.7625 | 18.71 | 300 * 6 | >22.4 | 1".2 | 2.08 Given the reported r-band magnitude of ~21.6 mag (Gill et al., GCN 45371) for observations starting at +4.55 hr post-EP-WXT detection, our observed limit is consistent. The presented magnitudes are calibrated using the field stars from the Pan-STARRS1 catalogue. The reported magnitude is not corrected for an expected galactic extinction of A_r = 0.15 mag, in the direction of the transient (Schlafly & Finkbeiner 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission are presented in Aryan et al. 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69. View this GCN Circular online at https://gcn.nasa.gov/circulars/45383. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43602] The EP-WXT trigger 01709279838 is likely a flaring star
by GCN Circulars 14 Aug '26

14 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45382 SUBJECT: The EP-WXT trigger 01709279838 is likely a flaring star DATE: 26/08/14 13:20:54 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> R.-Z. Li (YNAO), G. L. Huang (IHEP) and Y. Liu (NAOC) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709279838 at the time of 2026-08-14T12:49:35, is likely a stellar flare associated with PM J22403-4931 (Double or Multiple Star). The estimated flux of the flare is around 1.6 x 10^-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 2.7 x 10^30 erg/s. 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/45382. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43601] GRB 260805D: SVOM/GRM detection of a possible magnetar burst
by GCN Circulars 14 Aug '26

14 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45381 SUBJECT: GRB 260805D: SVOM/GRM detection of a possible magnetar burst DATE: 26/08/14 12:01:56 GMT FROM: zhangjinpeng(a)ihep.ac.cn SVOM/GRM team: Jin-Peng Zhang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Hui Yang (IRAP) Report on behalf of the SVOM team: SVOM/GRM detected GRB 260805D during the routine ground search at 2026-08-05T14:52:21.700 (T0), which is also detected by Fermi/GBM (TrigNum 807634346). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst mainly consists of two pulses with a T90 of 0.10 +0.03/-0.01 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn/gcn/2026/svgrb260805D.png In addition, the position of this burst, according to Fermi/GBM localization (RA = 284.2, Dec = -32.2, err = 34.7 degs), is located at about 68.9 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. Triangulation between SVOM/GRM and Fermi/GBM (3 sigma): https://www.bursthub.cn/gcn/2026/svgrb260805D_triangulation.png Considering the short duration and soft spectrum of this burst, and location consistent with several magnetars, it is likely a magnetar 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Jin-Peng Zhang (IHEP) (zhangjinpeng(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/45381. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43600] GRB 260808B: Liverpool Telescope further optical observations
by GCN Circulars 14 Aug '26

14 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45380 SUBJECT: GRB 260808B: Liverpool Telescope further optical observations DATE: 26/08/14 11:46:15 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek, D. A. Perley (LJMU), report: We observed the field of GRB 260808B (Bouchet et al., GCN 45316) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 8x120s exposures in SDSS griz filters, starting at 2026-08-13 01:30:02 UT, approximately 4.5 days after SVOM/ECLAIRS trigger. We detect a source in the stacked images, with the photometry given below, at the counterpart position reported by Turpin et al. (GCN 45318), Li et al. (GCN 45320), also observed by Wang et al. (GCN 45322), Adami et al. (GCN 45323), Saccardi et al. (GCN 45328), Schneider et al. (GCN 45329), Bochenek et al., (GCN 45330), with re-brightening reported by Li et al. (GCN 45359) and Guelfand et al. (GCN 45364). MJD (mid) T_mid-T_0 Filter Mag. (AB) 61265.06782 4.47 d g 22.19 ± 0.09 61265.08202 11.37 d r 21.77 ± 0.06 The photometry is in the AB magnitude system, was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/45380. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43599] GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
by GCN Circulars 13 Aug '26

13 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45379 SUBJECT: GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295 DATE: 26/08/13 20:00:32 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> A. de Ugarte Postigo (LAM), D. B. Malesani (DAWN/NBI and Radboud), S. Geier (GTC), M. A. Aloy (UV), C. C. Thoene (AbAO), J. P. U. Fynbo (DAWN/NBI), L. Galbany (IEEC-CSIC), L. Izzo (INAF/OACN and DARK/NBI), G. Lombardi (GTC), A. Martin-Carrillo (UCD), N. A. Rakotondrainibe (LAM), B. Schneider (LAM), N. R. Tanvir (Univ. Leicester), A. Cabrera-Lavers (GTC), A. M. Garcia Rodriguez (GTC) report: We observed the optical counterpart (Turpin et al., GCN 45318; Li et al., GCN 45320), recently reported to be brightening (Li et al., GCN 45359; Guelfand et al., GCN 45364) of GRB 260808B (Bouchet et al., GCN 45316; Brunet et al., GCN 45333) using the Gran Telescopio Canarias (GTC) equipped with the OSIRIS+ instrument. In a 30-s acquisition image (beginning on 2026-08-13 at 02:07:19 UT, that is 4.49 days after trigger), the optical afterglow is well detected with a magnitude of 21.70 +- 0.10 (AB), calibrated against nearby Pan-STARRS objects, and not corrected for Galactic extinction. Our measurement confirms the rebrightening (Li et al., GCN 45359; Guelfand et al., GCN 45364). A total of 3 spectra of 1200 s were secured, starting on 2025-08-13 at 02:10:52 UT (mid time 4.51 days after trigger), using grism R1000B. Continuum is visible over the wavelength range 3620-7800 AA. A number of metal absorption features are detected, which we interpret as due to Fe II, Mg II and Mg I, all at a common redshift z = 1.295, which we suggest to be the redshift of GRB 260808B. This work has used the GRBspec database at http://grbspec.eu (de Ugarte Postigo et al. 2014, doi:10.1117/12.2055774). View this GCN Circular online at https://gcn.nasa.gov/circulars/45379. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43598] GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
by GCN Circulars 13 Aug '26

13 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45378 SUBJECT: GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803) DATE: 26/08/13 19:45:08 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 808341387 at 19:16:22 on 13 Aug. 2026 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 240.3 deg Decl.(2000.0) = -61.7 deg The 1 sigma statistical error radius is 3.0 deg. We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB260813803/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB260813803/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB260813803/json View this GCN Circular online at https://gcn.nasa.gov/circulars/45378. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43597] GRB 260813A: Fermi GBM Final Real-time Localization
by GCN Circulars 13 Aug '26

13 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45377 SUBJECT: GRB 260813A: Fermi GBM Final Real-time Localization DATE: 26/08/13 19:26:57 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 19:16:22 UT on 13 Aug 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260813A (trigger 808341387.08523 / 260813803). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 231.4, Dec = -57.8 (J2000 degrees, equivalent to J2000 15h 25m, -57d 47'), with a statistical uncertainty of 2.5 degrees. The angle from the Fermi LAT boresight is 46.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260813803/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260813803/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260813803/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45377. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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