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

[vsnet-grb-info 43273] Fermi-LAT Gamma-ray Observations of IceCube-260622A
by GCN Circulars 30 Jun '26

30 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45058 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-260622A DATE: 26/06/30 23:04:48 GMT FROM: Simone Garrappa at Weizmann Institute of Science <simone.garrappa(a)weizmann.ac.il> S. Garrappa (Weizmann Institute of Science), L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg), J. Valverde (Marquette University) and C. Bartolini (University of Trento, INFN Bari) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC260622A neutrino event (GCN 45018) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2026-06-22 at 15:41:54.81 UTC (T0) with J2000 position RA = 173.36 (+0.5, -0.52) deg, Decl. = 1.34 (+0.58, -0.58) deg, 90% PSF containment. No cataloged >100 MeV gamma-ray sources are located within the 90% IC260622A localization error (4FGL-DR4; The Fourth Fermi-LAT catalog Data Release 4, The Fermi-LAT collaboration 2023, arXiv:2307.12546). In the preliminary list of the upcoming 5FGL catalog (FL16Y, Ballet et al. 2026), we find the gamma-ray source FL16Y 1134.2+0051 within the neutrino 90% PSF containment, at 0.53 deg from the best-fit neutrino position. From a preliminary analysis of Fermi-LAT data integrated on 1 month before T0, the source is significantly detected (> 5 sigma) in gamma-rays. The source is detected with a flux F = (1 +/- 0.3)e-7 ph cm^-2 s^-1 and best-fit power-law index 2.9 +/- 0.2, statistical errors only. A tentative counterpart to FL16Y 1134.2+0051 is the flat-spectrum radio source CRATES J1133+0058 (Healey et al. 2007, ApJS 171 1 61), ~9 arcmin from the Fermi-LAT best-fit localization and within its 68% error. We note that the localization region of IceCube-260622A is very close to the ecliptic; therefore the aforementioned results could be partially contaminated by the emission from the Moon. Time intervals with the Sun in the region of interest have been excluded from the analysis. We searched for the existence of intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5sigma) new excess emission (> 100 MeV) within the IC260622A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC260622A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 2.2e-10 ph cm^-2 s^-1 for ~18-years (2008-08-04 / T0), <1.2e-08 (<8.4e-07) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. For this source the Fermi-LAT contact person is Simone Garrappa (simone.garrappa at weizmann.ac.il). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/45058. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43272] EP260628a: EP-FXT follow-up observation
by GCN Circulars 30 Jun '26

30 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45057 SUBJECT: EP260628a: EP-FXT follow-up observation DATE: 26/06/30 02:51:19 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> X. Mao (NAO, CAS), C. Y. Dai (NJU), H. N. Yang, C. C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of EP260628a (X. Mao et al., GCN 45054) starting at 2026-06-29T06:40:57 (UTC), approximately 13.5 hours after the WXT detection. With an exposure time of 1.5 ks, no significant X-ray source was detected within the 2.8 arcmin radius of the EP-WXT position. The derived 0.5-10 keV upper limit is about 3.7 x 10^(-13) erg cm^-2 s^-1. 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/45057. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43271] GRB 260629A: Fermi GBM Final Real-time Localization
by GCN Circulars 29 Jun '26

29 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45056 SUBJECT: GRB 260629A: Fermi GBM Final Real-time Localization DATE: 26/06/29 15:19:19 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 15:06:58 UT on 29 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260629A (trigger 804438423.955606 / 260629630). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 146.1, Dec = 70.6 (J2000 degrees, equivalent to J2000 09h 44m, 70d 35'), with a statistical uncertainty of 10.5 degrees. The angle from the Fermi LAT boresight is 49.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260629630/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260629630/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260629630/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45056. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43270] Fermi GRB 260628A: Global MASTER-Net observations report
by GCN Circulars 29 Jun '26

29 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45055 SUBJECT: Fermi GRB 260628A: Global MASTER-Net observations report DATE: 26/06/29 03:33:42 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), M. Segura, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAGH robotic telescope [1] located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the Fermi GRB 260628A ( Fermi GBM team, GCN 45053) errorbox 19512 sec after notice time and 19564 sec after trigger time at 2026-06-29 03:17:28 UT, with upper limit up to 15.9 mag. Observations started at twilight. The observations began at zenith distance = 81 deg. The sun altitude is -9.9 deg. The galactic latitude b = -26 deg., longitude l = 39 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3405318 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 19595 | 2026-06-29 03:17:28 | MASTER-OAGH | (19h 41m 35.39s , +00d 26m 15.1s) | C | 60 | 14.6 | 19821 | 2026-06-29 03:21:14 | MASTER-OAGH | (19h 41m 18.87s , -01d 27m 54.5s) | C | 60 | 15.0 | 19821 | 2026-06-29 03:21:14 | MASTER-OAGH | (19h 35m 27.78s , -00d 49m 53.7s) | C | 60 | 14.5 | 19901 | 2026-06-29 03:22:35 | MASTER-OAGH | (19h 43m 03.30s , +02d 19m 13.8s) | C | 60 | 15.4 | 20056 | 2026-06-29 03:25:10 | MASTER-OAGH | (19h 47m 54.90s , +02d 57m 54.9s) | C | 60 | 14.9 | 20056 | 2026-06-29 03:25:10 | MASTER-OAGH | (19h 53m 46.15s , +02d 19m 54.0s) | C | 60 | 15.4 | 20137 | 2026-06-29 03:26:30 | MASTER-OAGH | (19h 45m 51.59s , +04d 13m 03.3s) | C | 60 | 15.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/45055. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43269] EP260628a: EP-WXT detection of a fast X-ray transient
by GCN Circulars 29 Jun '26

29 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45054 SUBJECT: EP260628a: EP-WXT detection of a fast X-ray transient DATE: 26/06/29 03:22:43 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> X. Mao, H. N. Yang (NAO, CAS), C. Y. Dai(NJU), C. C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of a fast X-ray transient, designated EP260628a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient was identified in the telemetry data. The transient started at 2026-06-28T17:08:08 (UTC) and lasted for about 30s, with a peak flux of ~ 7 x 10^(-9) erg cm^-2 s^-1 in 0.5-4 keV. The position of the transient is R.A. = 312.9884 deg, Dec. = -34.3748 (J2000), with an uncertainty radius of 2.8 arcmin in radius (90% confidence level, including both statistical and systematic uncertainties). There are no known X-ray sources in the WXT error circle. The average WXT 0.5-4 keV spectrum can be fitted by an absorbed power-law model with a fixed Galactic hydrogen column density of 4.86×10^20 cm^-2 and a photon index of 0.67 (-0.52/+0.52). The derived average unabsorbed 0.5-4 keV flux is 1.87 (-0.54/+0.71) x 10^(-9) erg cm^-2 s^-1. The uncertainties are at the 90% confidence level for the above parameters. Follow-up observations by EP-FXT will be arranged. Launched on 2024 January 9, Einstein Probe is a space-based X-ray observatory designed to monitor the dynamic X-ray sky and perform rapid follow-up observations of newly discovered transients (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/45054. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43268] GRB 260628A: Fermi GBM Final Real-time Localization
by GCN Circulars 28 Jun '26

28 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45053 SUBJECT: GRB 260628A: Fermi GBM Final Real-time Localization DATE: 26/06/28 22:03:44 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 21:51:24 UT on 28 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260628A (trigger 804376289.020238 / 260628911). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 308.2, Dec = -6.9 (J2000 degrees, equivalent to J2000 20h 32m, -6d 54'), with a statistical uncertainty of 14.3 degrees. The angle from the Fermi LAT boresight is 63.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260628911/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260628911/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260628911/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45053. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43267] The EP-WXT trigger 01709272671 is likely a flaring star
by GCN Circulars 28 Jun '26

28 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45052 SUBJECT: The EP-WXT trigger 01709272671 is likely a flaring star DATE: 26/06/28 02:08:13 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. P. Chen (SYSU), K. J. Zhang, D. Zhu (YNU), Y. J. Yi (BNU), Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709272671 at the time of 2026-06-27T17:53:04 (UTC), is likely a stellar flare associated with RX J1942.2-2045. 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 4.8 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/45052. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43266] EP260626a: further Liverpool Telescope optical upper limits
by GCN Circulars 27 Jun '26

27 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45051 SUBJECT: EP260626a: further Liverpool Telescope optical upper limits DATE: 26/06/27 17:25:38 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 EP260626a (Chen et al., GCN 45047; Chen et al., GCN 45050) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 8x150s exposures in SDSS r and z filters, starting at 2026-06-27 01:59:23 UT, approximately 20.57 hours after EP trigger. The stacked exposures were subtracted from PanSTARRS reference imaging using custom PSF-matching image subtraction code utilising Swarp, SourceExtractor, and PSFex. We do not detect any new sources in the error EP/WXT region (Chen et al., GCN 45047), including at the position of the uncatalogued X-ray source reported by Chen et al. (GCN 45047), down to 3 sigma upper limits of r> 23.44 and z> 22.94. This is consistent with upper limits from Eyles-Ferris et al. (GCN 45048) and Magnani et al. (GCN 45049). 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/45051. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43265] EP260626a: EP-FXT follow-up observation
by GCN Circulars 27 Jun '26

27 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45050 SUBJECT: EP260626a: EP-FXT follow-up observation DATE: 26/06/27 15:28:42 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. P. Chen (SYSU), K. J. Zhang, D. Zhu (YNU), W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of EP260626a (J. P. Chen et al., GCN 45047) approximately 10.8 hours after the WXT detection, with an exposure time of 6.1 ks. An uncatalogued X-ray source was detected within the WXT error circle at R.A. = 277.4479, Dec. = 21.2498 (J2000), with a positional uncertainty of 10.0 arcsec (radius, 90% C.L. statistical and systematic). The FXT spectrum can be fitted with an absorbed powerlaw with a hydrogen column density fixed at the Galactic value of 2.04 x 10^21 cm^-2 and a photon index of 2.13 (+0.6, -0.6). The derived unabsorbed 0.5-10 keV flux is approximately 9.3 (+4.5, -2.1) x 10^-14 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. No optical counterpart has been detected (R. A. J. Eyles-Ferris et al., GCN 45048; Francesco Magnani et al., GCN 45049). 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/45050. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43264] EP260526a: COLIBRÍ optical upper limit
by GCN Circulars 27 Jun '26

27 Jun '26

TITLE: GCN CIRCULAR NUMBER: 45049 SUBJECT: EP260526a: COLIBRÍ optical upper limit DATE: 26/06/27 10:31:22 GMT FROM: F. Magnani at Aix-Marseille Université, CPPM/CNRS <francesco.magnani.work(a)gmail.com> Francesco Magnani (CPPM), Fredd Sánchez Álvarez (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), and Alan M. Watson (UNAM) report: We imaged the field of the EP 260526a (J.P. Chen et al., GCN Circ. 45047) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-06-27T07:56:30 to 09:19:26 UTC (from 26.5 to 27.9 hours after the trigger) and obtained 64 minutes of simultaneous exposure in the r, z filters. The data were reduced, coadded, and analysed with the COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source at the WXT source position (J.P. Chen et al., GCN Circ. 45047) down to the following 3-sigma limit: r > 23.87 z > 23.15 This upper limit is consistent with the one reported by R. A. J. Eyles-Ferris et al., GCN Circ. 45048. We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/45049. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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