July 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 43371] GRB 260706A: ATCA detection of possible radio counterpart
by GCN Circulars 14 Jul '26

14 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45156 SUBJECT: GRB 260706A: ATCA detection of possible radio counterpart DATE: 26/07/14 14:39:13 GMT FROM: James Leung at U. Toronto / HUJI <jamesk.leung(a)utoronto.ca> J. K. Leung (U. Toronto/HUJI), G. E. Anderson (CSIRO), S. Chastain (TTU), L. Rhodes (TSI/McGill), A. Gulati (U. Sydney), A. J. van der Horst (GWU) on behalf of the PanRadio GRB collaboration We performed observations of GRB 260706A, which was detected by SVOM/ECLAIRs (Alaux et al., GCN 45089) and Fermi/GBM (Fermi GBM team, GCN 45088; Trigg et al., GCN 45093), using the Australia Telescope Compact Array (ATCA) from 14:30 - 23:00 UT on 11 July 2026 (~5.1 days post-burst) using the 4cm (4-12 GHz) receiver. Our observations were centred on the position of the uncatalogued X-ray source found in EP-FXT follow-up observations (Liang et al., GCN45097; Pillas et al., GCN 45114). In our preliminary analysis, we detect a radio source at ~0.2 mJy at 8 GHz with a spectral index of ~1.5 indicating that the radio counterpart is likely to be self-absorbed at this epoch. We measured the position of the radio source to be: RA (J2000)=2:15:15.4 DEC (J2000)=-49:09:02.7 with a positional uncertainty radius of ~0.5". No previous radio source was detected at this position in the Rapid ASKAP Continuum Survey (RACS; McConnell et al., PASA, 37, e048). The radio source is ~2.7" away from the reported position of the EP-FXT uncatalogued X-ray source position (Liang et al., GCN45097), but is consistent within its ~10" positional uncertainty radius. It is the only radio source detected above the 5-sigma = 30 microJy/beam within the SVOM/ECLAIRs error circle (Alaux et al., GCN 45089). We therefore suggest this source is possibly the radio counterpart to GRB 260706A. Further observations are planned. We thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO. View this GCN Circular online at https://gcn.nasa.gov/circulars/45156. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43370] GRB 260705A: ATCA radio observations
by GCN Circulars 14 Jul '26

14 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45155 SUBJECT: GRB 260705A: ATCA radio observations DATE: 26/07/14 14:38:03 GMT FROM: James Leung at U. Toronto / HUJI <jamesk.leung(a)utoronto.ca> J. K. Leung (U. Toronto/HUJI), G. E. Anderson (CSIRO), S. Chastain (TTU), L. Rhodes (TSI/McGill), A. Gulati (U. Sydney), A. J. van der Horst (GWU) on behalf of the PanRadio GRB collaboration We performed observations of GRB 260705A, which was detected by SVOM/ECLAIRs (Saccardi et al., GCN 45079) and Fermi/GBM (Hamburg, GCN 45080), using the Australia Telescope Compact Array (ATCA) from 14:30 - 23:00 UT on 11 July 2026 (~6.3 days post-burst) using the 4cm (4-12 GHz) receiver. Our observations were centred on the position of the candidate optical counterpart detected by SOAR and Gemini-South telescopes (Freeburn et al., GCN 45105). In our preliminary analysis, we do not detect any radio source with a position consistent with the candidate optical counterpart. The rms noise of the observation at 8 GHz was 8 microJy/beam. However, we find multiple radio sources within the SVOM/ECLAIRs error circle (Saccardi et al., GCN 45079) that were not detected in the Rapid ASKAP Continuum Survey (RACS; McConnell et al., PASA, 37, e048) and will continue to monitor these sources. In regards to the possible association with GRB 260705B (Freeburn et al., GCN 45105), we note that the separation between the reported positions for GRB 260705A (Saccardi et al., GCN 45079) and GRB 260705B (Fermi GBM Team, GCN 45081) is ~11 deg; with the uncertainties on the positions being 7.06 arcmin and 3.0 deg, respectively; the positions of these GRBs are not statistically consistent. Further observations are planned. We thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO. View this GCN Circular online at https://gcn.nasa.gov/circulars/45155. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43369] GRB 260714A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Jul '26

14 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45154 SUBJECT: GRB 260714A: Fermi GBM Final Real-time Localization DATE: 26/07/14 14:28:21 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 14:16:56 UT on 14 Jul 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260714A (trigger 805731421.523672 / 260714595). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 59.3, Dec = 14.1 (J2000 degrees, equivalent to J2000 03h 57m, 14d 05'), with a statistical uncertainty of 3.5 degrees. The angle from the Fermi LAT boresight is 67.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260714595/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260714595/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260714595/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45154. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43368] EP260713a: Einstein Probe detection of an X-ray transient
by GCN Circulars 14 Jul '26

14 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45153 SUBJECT: EP260713a: Einstein Probe detection of an X-ray transient DATE: 26/07/14 11:17:03 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> X. H. Tang (THU), M. J. Liu (NAO, CAS), Y. L. Hua (PMO, CAS), W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient designated EP260713a by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient was detected at 2026-07-13T15:25:54 (UTC) at R.A. = 283.210 deg, DEC = -13.129 deg (J2000) with an uncertainty of 2.4 arcmin in radius (90% C.L. statistical and systematic). Preliminary analysis shows that the WXT spectrum can be fitted by an absorbed blackbody spectrum with NH = 0.8(-0.7/+1.8)e22 cm-2 and a temperature of 0.12(-0.07/+0.21) keV. The derived 0.5-4 keV flux is 6.9(-1.2/+2.9)e-12 erg/s/cm^2. The uncertainties are given at the 90% confidence level for the above parameters. An observation on this X-ray transient was performed by the Follow-up X-ray Telescope (FXT) on board EP at 2026-07-14T07:01:57 (UTC), which detected an uncatalogued X-ray source at R.A. = 283.2049, DEC = -13.1132 deg (J2000, with an uncertainty of about 20 arcsec), consistent with the position of the WXT transient within the uncertainties. Further information will be updated when the telemetry data are received. 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/45153. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43367] GRB 260619A: SVOM/VT continuous optical observations
by GCN Circulars 13 Jul '26

13 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45152 SUBJECT: GRB 260619A: SVOM/VT continuous optical observations DATE: 26/07/14 03:36:48 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC) and J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team. SVOM/VT performed several ToO observations for GRB 260619A detected by Fermi-LAT (sb26061901, Goto et al., GCN 44985；Dagnoneau et al., GCN 45041). The latest observation started at 2026-07-10T06:53:45 UTC, about 21.196 d post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. The optical candidate (Ducoin et al., GCN 44999; Li et al., GCN 45003; He et al., GCN 45008; Malesani et al., GCN 45015) shows significant fading of approximately 1 magnitude in VT_B in the latest observation compared with earlier ones (Li et al., GCN 45003), while remaining stable in VT_R. The following measurements are in the AB magnitude and are not corrected for Galactic extinction: Mid time | Band | Exposure Time | Brightness 21.24 d VT_B 64*70 s 23.9 +/- 0.3 mag 21.24 d VT_R 63*70 s 22.4 +/- 0.2 mag 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/45152. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43366] GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
by GCN Circulars 13 Jul '26

13 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45151 SUBJECT: GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening DATE: 26/07/14 02:57:05 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC) and J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation for GRB 260618B detected by Fermi-LAT (Gupta et al., GCN 44983), Fermi-GBM (Fermi GBM team, GCN 44979; Veres et al., GCN 45010) and Konus-Wind (Ridnaia et al., GCN 45038). The latest observation started at 2026-07-10T09:59:57 UTC, about 21.71 d post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. The optical candidate (Li et al., GCN 45001; Shi et al., GCN 45014) became fainter in both channels and redder relative to earlier observations (Li et al., GCN 45001). The following measurements are in the AB magnitude and are not corrected for Galactic extinction: Mid time | Band | Exposure Time | Brightness 21.73 d VT_B 37*70 s 22.3 +/- 0.2 mag 21.73 d VT_R 34*70 s 21.6 +/- 0.1 mag 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/45151. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43365] GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
by GCN Circulars 13 Jul '26

13 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45150 SUBJECT: GRB 260708A: slowly decaying X-ray emission observed by EP/FXT DATE: 26/07/14 02:48:42 GMT FROM: Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi(a)ynao.ac.cn> R.-Z. Li (YNAO, CAS), J. Mao (YNAO, CAS), S. Antier (IJCLAB), M. Pillas (IAP), D. Turpin (CEA/Irfu), O. Pyshna (Caltech) report on behalf of a larger collaboration: We report two EP/FXT Target of Opportunity (ToO) observations of the Fermi long GRB 260708A (Fermi/GBM Team, GCN 45115; Fermi/LAT, Holzmann Airasca et al., GCN 45117; GECAM-B, Ren et al., GCN 45126; Glowbug, Cheung et al., GCN 45130). The first EP/FXT follow-up observation started at 2026-07-11T01:06:38 (UTC), approximately 2.62 days after the Fermi/GBM trigger, with a total exposure time of 2.7 ks. EP/FXT detected an uncatalogued X-ray source at the following coordinates (J2000): R.A., Decl. = 225.6537, -43.8844 with a localization uncertainty of 10 arcsec radius (90% confidence level, including both statistical and systematic uncertainties). The X-ray position is consistent with that of AT 2026stf reported by MASTER (Shilova et al., GCN 45123). The average 0.5-10 keV EP/FXT spectrum can be fitted by an absorbed power law with a Galactic hydrogen column density of (0.36 +/- 0.12) x 10^22 cm^-2 and a photon index of 2.25 +/- 0.32. The derived average unabsorbed 0.5-10 keV flux is (1.31 +/- 0.13) x 10^-12 erg cm^-2 s^-1. The second EP/FXT follow-up observation started at 2026-07-13T12:09:39 (UTC), approximately 5.08 days after the Fermi/GBM trigger, with a total exposure time of 6 ks. On-ground analysis of the EP/FXT data again detected an uncatalogued X-ray source consistent with the source detected in the first observation. The average 0.5-10 keV EP/FXT spectrum can be fitted by an absorbed power law with a Galactic hydrogen column density of (0.40 +/- 0.5) x 10^22 cm^-2 and a photon index of 2.36 +/- 0.38. The derived average unabsorbed 0.5-10 keV flux is (5.46 +/- 0.68) x 10^-13 erg cm^-2 s^-1. The temporal decay index of X-ray emission between the two observations is 1.32 +/- 0.24. Given the slow temporal evolution observed in both the optical band (Shilova et al., GCN 45123; Freeberg et al., GCN 45127; Shi et al., GCN 45140; Sheng et al., GCN 45147) and the X-ray band, optical spectroscopy is strongly encouraged to determine the classification of the source. All quoted uncertainties correspond to the 1-sigma confidence level. 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/45150. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43364] EP260623a: KAIT optical observations
by GCN Circulars 13 Jul '26

13 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45149 SUBJECT: EP260623a: KAIT optical observations DATE: 26/07/13 17:04:57 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of EP260623a (Wang et al., GCN 45020, 45035; Svinkin et al., GCN 45046) at 5.85 hours after the burst, and again at 1.34 days after the burst. A set of clear (roughly R) filter images were obtained. We clearly detected the optical afterglow (Li et al., GCN 45021; Izzo et al., GCN 45022; Angulo et al., GCN 45024; Brivio et al., GCN 45025; Jiang et al., GCN 45026; Li et al., GCN 45027; Jelinek et al., GCN 45029; Lee et al., GCN 45030; Saikia et al., GCN 45034; Bochenek & Perley, GCN 45040; Busmann et al., GCN 45042; Brivio et al., GCN 45045) in our coadd images. We measure its brightness decayed from 18.8 +/- 0.1 mag (Vega) to 22.2 +/- 0.2 mag with a power-law decay index of ~2.0. View this GCN Circular online at https://gcn.nasa.gov/circulars/45149. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43363] EP260711a: EP-FXT follow-up observation
by GCN Circulars 13 Jul '26

13 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45148 SUBJECT: EP260711a: EP-FXT follow-up observation DATE: 26/07/13 14:15:55 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.Wu (NJU), G. Y. Zhao (SYSU), Z.-Y. Jian (THU), and H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: We performed a follow-up observation of EP260711a (GCN 45139) with EP-FXT. The observation started at 2026-07-12 07:29:45 (UTC), about 22 hr after the EP-WXT detection, with a total exposure time of around 4.4 ks. No bright X-ray source was found in one FXT module observation. A weak uncatalogued source, with SNR of 3.2, was found within the WXT error circle after stacking the FXT A and FXT B data. The position of the source is at R.A., Dec. = 213.2229, -58.8956 deg (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The average unabsorbed flux is around 3 x 10^(-14) erg/s/cm^2 in the 0.5-10 keV energy band. It is still unclear if the FXT detection is associated with EP260711a. 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/45148. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43362] GRB 260708A: GRANDMA Optical Observations
by GCN Circulars 13 Jul '26

13 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45147 SUBJECT: GRB 260708A: GRANDMA Optical Observations DATE: 26/07/13 14:05:35 GMT FROM: Xinyue Sheng at Queens University Belfast <xysheng.astro(a)gmail.com> X. Sheng (QUB), D. Turpin (CEA/Irfu), O. Pyshna (Caltech), R. Strausbaugh (EIU), A. Iskandarova (ShAO), S. Rahimli (Sumgayit State Uni), V. Morozov (KU Leuven), S. Antier (IJCLAB), A. Simon (TShNU of Kyiv), L. Wyrzykowski (Uni. Warsaw/NCBJ), J. Hambsch (VVS, GEOS, BAV), M. Freeberg (KNC), R. Hellot (KNC), A. Klotz (IRAP), E. Jehin (ULiège), M. Ferrais (ULiège), Rui-Zhi (YNAO), J. Mao (YNAO) on behalf of on GRANDMA collaboration: We observed the field of the Fermi Long GRB 260708A (Fermi GBM team, GCN 45115; Fermi/LAT, Holzmann Airasca et al., GCN45117,; GECAM-B, Ren et al., GCN45126; Glowbug, Cheung et al., GCN 45130). The observations started at 14:30:42 UTC on the 9 of July 2026, 1.18 days post the Fermi Trigger. We detected the optical afterglow candidate, reported by MASTER (Shilova et al, GCN 45123), in several epochs, using the 60cm telescope at les Makes Observatory, the LCO 0.4m telescope at the SAA Observatory, the TRAPPIST-South telescope at la SIlla Observatory, and Kilonova Catcher. However, we observed after template substraction a softer decay than usual for the GRBs. A subset of the photometry corrected for Galactic extinction is reported in the public ACME service Skyportal/ICARE https://skyportal-icare.ijclab.in2p3.fr/source/GRB-260708A. To access, one simply needs to create an account using your ORCID id. The data were reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the Sloan filters were calibrated using the PanSTARRS DR1 catalog. Images obtained with the Johnson-Cousins filters were calibrated using the Gaia DR3 Synphot catalog. Our results are consistent across GRANDMA but not totally with LCO (GCN 45140). Further template taken at later time are needed. The observations are performed under the P7 campaign of GRANDMA to monitor SVOM alerts and LSST alerts from explosive fast transients filtered by BOOM/Babamul and FINK. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) View this GCN Circular online at https://gcn.nasa.gov/circulars/45147. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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