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[vsnet-grb-info 38690] GRB 250609A: Fermi GBM Final Real-time Localization
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40652 SUBJECT: GRB 250609A: Fermi GBM Final Real-time Localization DATE: 25/06/09 08:57:49 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 SHORT GRB At 08:47:18 UT on 9 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250609A (trigger 771151643.61016 / 250609366). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 150.6, Dec = -8.4 (J2000 degrees, equivalent to J2000 10h 02m, -8d 24'), with a statistical uncertainty of 36.2 degrees. The angle from the Fermi LAT boresight is 81.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40652. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38689] GRB 250607A: SVOM/GRM observation of a long burst
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40651 SUBJECT: GRB 250607A: SVOM/GRM observation of a long burst DATE: 25/06/09 03:13:00 GMT FROM: wenlongzhang2018(a)163.com SVOM/GRM team: Wen-Long Zhang, Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Jean-Luc Atteia (IRAP) report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a long burst GRB 250607A (SVOM trigger reference: sb25060704) at 2025-06-07T14:00:56.000 UTC (T0), which is also detected by Fermi/GBM ( Fermi GBM team., GCN #40648). 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 12.60 +7.20/-5.40 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250607A.png In addition, the position of this burst, as determined by Fermi/GBM (RA = 243.84, Dec = -24.71 , GCN #40648), is located at about 53 degrees from the SVOM optical axis, and outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-5s to T0+5s is best fitted by a power law function. The power law index is -1.82+/-0.08. The event fluence (10-1000 keV) in this time interval is (1.37 +0.15/-0.15)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 point of contact for this burst is: Wen-Long Zhang (IHEP)(zhangwl(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/40651. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38688] EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
by GCN Circulars 08 Jun '25

08 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40650 SUBJECT: EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7 DATE: 25/06/08 09:27:31 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, S.-Y. Wu, A. J. Castro-Tirado, E. J. Fernandez-Garcia, M.D. Caballero-Garcia, S. Guziy, G. Garcia-Segura, R. Sanchez-Ramirez (IAA-CSIC), Y.-D. Hu (INAF-OAB), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), L. Hernandez-Garcia (Univ. de Valparaiso), M. Gritsevich (Univ. of Helsinki), S. Jeong (ADD, Daejeon), D. Hiriart (IA-UNAM, Ensenada), W. H. Lee (UNAM, Mexico DF), D.-R. Xiong (Yunnan Observatories of CAS), B.-B. Zhang (Nanjing Univ.) and A. Maury (Space, San Pedro de Atacama), on behalf of a larger collaboration, report: Following the detection of trigger 01709178244 by EP-WXT (Hu et al. GCN 40649), both the 0.6m robotic telescopes BOOTES-5/JGU robotic telescope at San Pedro Martir Observatory (Mexico) and BOOTES-7 at San Pedro de Atacama (Chile) responded to the alert on June 8, 5:00 UT (i.e. 1 min after notification and 6.5 min after the detection). Within the reported EP-FXT error circle we find the star Gaia DR3 6730332160799599744 decreasing 1.2 mag in brightness (g filter) and 0.8 mag (r filter) during a 120 min time interval, confirming the EP X-ray trigger due to a stellar flare. We thank the staff at San Pedro de Atacama Celestial Observations and San Pedro Martir Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/40650. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38687] The EP-WXT trigger 01709178244 is likely a flaring star
by GCN Circulars 08 Jun '25

08 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40649 SUBJECT: The EP-WXT trigger 01709178244 is likely a flaring star DATE: 25/06/08 05:41:59 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. F. Hu (PMO, CAS), Q. C. Liu (THU), B. B. Zhang (BNU), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709178244 at the time of 2025-06-08T04:53:30 (UTC), is likely a stellar flare associated with Gaia DR3 6730332160799599744. The estimated flux of the flare is around 1.6 x 10^-10 erg/s/cm^2 in 0.5-4 keV, corresponding to an X-ray luminosity of around 3.3 x 10^32 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/40649. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38686] GRB 250607A: Fermi GBM Final Localization
by GCN Circulars 07 Jun '25

07 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40648 SUBJECT: GRB 250607A: Fermi GBM Final Localization DATE: 25/06/07 15:22:38 GMT FROM: rhamburg(a)usra.edu The Fermi GBM team reports the detection of a likely LONG GRB. "At 14:00:55.64 UT on 07 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250607A (trigger 770997660/250607584). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 243.84, Dec = -24.71 (J2000 degrees, equivalent to J2000 16h 15m, -24d 42'), with a statistical uncertainty of 10.15 degrees. The angle from the Fermi LAT boresight is 90 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250607584/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250607584/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250607584/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/40648. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38685] EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
by GCN Circulars 07 Jun '25

07 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40647 SUBJECT: EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7 DATE: 25/06/07 11:28:27 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, S.-Y. Wu, A. J. Castro-Tirado, E. J. Fernandez-Garcia, M.D. Caballero-Garcia, S. Guziy, G. Garcia-Segura, R. Sanchez-Ramirez (IAA-CSIC), Y.-D. Hu (INAF-OAB), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), L. Hernandez-Garcia (Univ. de Valparaiso), M. Gritsevich (Univ. of Helsinki), D.-R. Xiong (Yunnan Observatories of CAS), B.-B. Zhang (Nanjing Univ.) and A. Maury (Space, San Pedro de Atacama), on behalf of a larger collaboration, report: Following the detection of trigger 01709178069 by EP-WXT (Hu et al. GCN 40646), both the 0.6m robotic telescopes BOOTES-6/DPRT 0.6m at Boyden Observatory in Maselspoort (South Africa) and BOOTES-7 at San Pedro de Atacama (Chile) responded to the alert on June 7, 23:45 UT (i.e. 2 min after notification and 7 min after the detection). Within the reported EP-FXT error circle we find the star UCAC4 204-077663 decreasing 0.25 mag in brightness (clear filter) during a 30 min time interval. Subsequent observations using the g filter and starting on June 8, 00:23 we find a decrease in 0.7 mag during a 2 hour time interval, confirming the EP X-ray trigger due to a stellar flare. We thank the staff at San Pedro de Atacama Celestial Observations and Boyden Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/40647. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38684] The EP-WXT trigger 01709178069 is likely a flaring star
by GCN Circulars 07 Jun '25

07 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40646 SUBJECT: The EP-WXT trigger 01709178069 is likely a flaring star DATE: 25/06/07 01:58:34 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. F. Hu, Y. Wang (PMO, CAS), H. Sun, W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709178069 at the time of 2025-06-06T23:38:19 (UTC), is likely a stellar flare associated with UCAC4 204-077663. The estimated flux of the flare is around 8 x 10^-11 erg/s/cm^2 in 0.5-4 keV, corresponding to an X-ray luminosity of around 1.1 x 10^32 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/40646. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38682] GRB 250605A: VT optical upper limit
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40645 SUBJECT: GRB 250605A: VT optical upper limit DATE: 25/06/06 15:40:20 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Z. H. Yao, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT conducted ToO follow-up observations of the GRB 250605A (Gupta et al., GCN 40633, Melandri et al., GCN 40644). The observation started on 2025-06-06T05:02:39 UT in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources are detected in single or stacked images within the Swift/XRT error box (Evans et al., GCN 40642) and the possible optical candidate reported by Gompertz et al. (GCN 40634). The 3 sigma limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 11.28 hour VT_B 59*70 sec >23.6 mag 11.28 hour VT_R 59*70 sec >23.6 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/40645. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38683] GRB 250605A: VT optical upper limit
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40645 SUBJECT: GRB 250605A: VT optical upper limit DATE: 25/06/06 15:40:20 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Z. H. Yao, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT conducted ToO follow-up observations of the GRB 250605A (Gupta et al., GCN 40633, Melandri et al., GCN 40644). The observation started on 2025-06-06T05:02:39 UT in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources are detected in single or stacked images within the Swift/XRT error box (Evans et al., GCN 40642) and the possible optical candidate reported by Gompertz et al. (GCN 40634). The 3 sigma limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 11.28 hour VT_B 59*70 sec >23.6 mag 11.28 hour VT_R 59*70 sec >23.6 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/40645. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38681] GRB 250605A: Swift-XRT refined Analysis
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40644 SUBJECT: GRB 250605A: Swift-XRT refined Analysis DATE: 25/06/06 11:02:50 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 7.0 ks of XRT data for GRB 250605A, from 90 s to 50.2 ks after the trigger. The data comprise 149 s in Windowed Timing (WT) mode (the first 6 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=4.36 (+0.19, -0.15). At T+164 s the decay flattens to an alpha of 3.19 (+0.29, -0.32) before breaking again at T+326 s to a final decay with index alpha=0.79 (+/-0.07). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.12 (+0.06, -0.05). The best-fitting absorption column is 2.59 (+0.20, -0.19) x 10^21 cm^-2, in excess of the Galactic value of 4.3 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.10 (+0.13, -0.12) and a best-fitting absorption column of 2.9 (+/-0.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.9 (+/-0.5) x 10^21 cm^-2 Galactic foreground: 4.3 x 10^20 cm^-2 Excess significance: 8.7 sigma Photon index: 2.10 (+0.13, -0.12) If the light curve continues to decay with a power-law decay index of 0.79, the count rate at T+24 hours will be 0.085 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x 10^-12 (4.7 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01321323. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40644. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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