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[vsnet-grb-info 42415] GRB 260414A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Apr '26

14 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44293 SUBJECT: GRB 260414A: Fermi GBM Final Real-time Localization DATE: 26/04/14 06:42:26 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 06:31:55 UT on 14 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260414A (trigger 797841120.53845 / 260414272). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 17.0, Dec = 39.8 (J2000 degrees, equivalent to J2000 01h 07m, 39d 47'), with a statistical uncertainty of 6.0 degrees. The angle from the Fermi LAT boresight is 48.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260414272/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260414272/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260414272/… View this GCN Circular online at https://gcn.nasa.gov/circulars/44293. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42414] The EP-WXT trigger 01709260122 is likely a flaring star
by GCN Circulars 14 Apr '26

14 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44292 SUBJECT: The EP-WXT trigger 01709260122 is likely a flaring star DATE: 26/04/14 06:10:11 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> K. R. Ni (CCNU), Q. C. Liu (THU), D. Y. Li and H. W. Pan (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709260122 at the time of 2026-04-14T05:13:09, is likely a stellar flare associated with RX J1553.0+4457. The estimated flux of the flare is around 1.26e-9 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 2.05e32 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/44292. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42413] Fermi GRB 260413A: Global MASTER-Net observations report
by GCN Circulars 14 Apr '26

14 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44291 SUBJECT: Fermi GRB 260413A: Global MASTER-Net observations report DATE: 26/04/14 00:15:57 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), C.Francile, 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 260413A ( Fermi GBM team, GCN 44289) errorbox 36329 sec after notice time and 36340 sec after trigger time at 2026-04-13 23:49:17 UT, with upper limit up to 20.7 mag. The observations began at zenith distance = 45 deg. The sun altitude is -20.6 deg. The galactic latitude b = -31 deg., longitude l = 273 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3250278 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 36400 | 2026-04-13 23:49:17 | MASTER-OAFA | (05h 00m 14.08s , -47d 04m 31.9s) | C | 120 | 20.6 | 36536 | 2026-04-13 23:51:33 | MASTER-OAFA | (05h 00m 10.91s , -47d 02m 46.4s) | C | 120 | 20.7 | 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/44291. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42412] GRB 260410A: Glowbug gamma-ray detection of a short burst
by GCN Circulars 13 Apr '26

13 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44290 SUBJECT: GRB 260410A: Glowbug gamma-ray detection of a short burst DATE: 26/04/13 21:49:59 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 260410A, which was detected by Fermi/GBM (GCN 44252, 44258), Fermi/LAT (GCN 44253), CALET (GCN 44283), Konus-Wind (GCN 44286), and Insight-HXMT/HE (GCN 44287). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-04-10 07:03:55.848 with a duration of 0.38 s and a total significance of about 46 sigma. The light curve comprises a single peak at ~T0+0.2s. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/44290. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42411] GRB 260413A: Fermi GBM Final Real-time Localization
by GCN Circulars 13 Apr '26

13 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44289 SUBJECT: GRB 260413A: Fermi GBM Final Real-time Localization DATE: 26/04/13 13:54:18 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 13:43:37 UT on 13 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260413A (trigger 797780622.310696 / 260413572). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 87.0, Dec = -64.0 (J2000 degrees, equivalent to J2000 05h 47m, -64d 00'), with a statistical uncertainty of 26.0 degrees. The angle from the Fermi LAT boresight is 15.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260413572/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260413572/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260413572/… View this GCN Circular online at https://gcn.nasa.gov/circulars/44289. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42410] GRB 260410B: Insight-HXMT/HE detection
by GCN Circulars 13 Apr '26

13 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44288 SUBJECT: GRB 260410B: Insight-HXMT/HE detection DATE: 26/04/13 13:29:15 GMT FROM: zhangjinpeng(a)ihep.ac.cn Jin-Peng Zhang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2026-04-10T12:22:26.900 (T0), Insight-HXMT/HE detected GRB 260410B, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #44255) and SVOM/GRM (Chen-Wei Wang et al., GCN #44257). The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 0.2 +/- 0.04 s. Insight-HXMT/HE detected a total of 1102 counts from this burst. The Insight-HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb260410B.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://hxmten.ihep.ac.cn View this GCN Circular online at https://gcn.nasa.gov/circulars/44288. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42409] GRB 260410A: Insight-HXMT/HE detection
by GCN Circulars 13 Apr '26

13 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44287 SUBJECT: GRB 260410A: Insight-HXMT/HE detection DATE: 26/04/13 12:54:41 GMT FROM: zhangjinpeng(a)ihep.ac.cn Jin-Peng Zhang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2026-04-10T07:03:56.950 (T0), Insight-HXMT/HE detected GRB 260410A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #44252; Hamburg et al., GCN #44258) and Fermi/LAT (Holzmann Airasca et al., GCN #44253). The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 0.6 +0.5/-0.3 s. Insight-HXMT/HE detected a total of 1462 counts from this burst. The Insight-HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb260410A.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the low gain mode with the energy range of about 300-3000 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://hxmten.ihep.ac.cn View this GCN Circular online at https://gcn.nasa.gov/circulars/44287. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42408] Konus-Wind detection of GRB 260410A (short/hard)
by GCN Circulars 13 Apr '26

13 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44286 SUBJECT: Konus-Wind detection of GRB 260410A (short/hard) DATE: 26/04/13 11:52:18 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The short-duration GRB 260410A (Fermi-GBM detection: Fermi GBM team, GCN Circ. 44252, Hamburg et al., GCN Circ. 44258; Fermi-LAT detection: Holzmann Airasca et al., GCN Circ. 44253; CALET-GBM detection: Ricciarini et al., GCN Circ. 44283) triggered Konus-Wind at T0=25436.09 s UT (07:03:56.090). The burst light curve shows a multipeaked structure, which starts at ~T0-0.1 s and has a total duration of ~0.3 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260410_T25436/ As observed by Konus-Wind, the burst had a fluence of 3.36(-0.54,+0.53)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.054 s, of 2.53(-0.69,+0.68)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.192 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.06(-0.34,+0.62), the high energy photon index beta = -2.06(-0.51,+0.28), the peak energy Ep = 784(-283,+341) keV (chi2 = 21/27 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/44286. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42407] GRB 260411B: GECAM-B observation of a long burst
by GCN Circulars 13 Apr '26

13 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44285 SUBJECT: GRB 260411B: GECAM-B observation of a long burst DATE: 26/04/13 10:33:45 GMT FROM: xueyuan zao <zaoxueyuan(a)gmail.com> Xue-Yuan Zao, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 260411B, at 2026-04-11T08:04:42.550 UTC, which is also detected by Fermi/GBM (Fermi GBM team, GCN #44262 and #44266), SVOM/GRM (Chen-Wei Wang et al., GCN #44268) and Feimi/LAT (F. Longo et al., GCN#44277). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of two emission episodes with a total duration (T90) of 18.8 +3.8/-2.0 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260411B.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/44285. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42406] EP260321a: SVOM/VT optical observations and color changes around peak
by GCN Circulars 13 Apr '26

13 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44284 SUBJECT: EP260321a: SVOM/VT optical observations and color changes around peak DATE: 26/04/13 10:24:49 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, Y. N. Ma, C. Wu, L. P. Xin, Y. L. Qiu, 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, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team. SVOM/VT performed several ToO observations of EP260321a triggered by Einstein Probe (Huang et al., GCN 44068) in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously from 2026-03-21 (Ma et al., GCN 44074), 2026-03-23, 2026-03-26, 2026-03-28, 2026-04-01, 2026-04-04, 2026-04-07, 2026-04-10 and 2026-04-12. The optical counterpart (Lee et al., GCN 44070; Tanvir et al., GCN 44082; Moran et al., GCN 44083, Ahumada et al., GCN 44084, Liu et al., GCN 44087; Sankar et al. GCN 44089; de Ugarte Postigo et al., GCN 44091; Xu et al., GCN 44092; Pankov et al. GCN 44103; Corcoran et al., GCN 44105; Rastinejad et al., GCN 44107; Gao et al., GCN 44110; He et al., GCN 44117; Zhang et al., GCN 44171) showed a rise to a peak after trigger in both channels, followed by a decline. The peak in VT_B was at approximately 10.7 days post trigger. The preliminary measurements are in the AB magnitude and are not corrected for Galactic extinction: Mid time | Band | Exposure Time | Brightness 1.906 hr VT_B 53*50 sec 19.70+/-0.05 mag 1.906 hr VT_R 53*50 sec 19.98+/-0.06 mag 19.75 d VT_B 17*50 sec 17.48+/-0.03 mag 19.75 d VT_R 17*50 sec 17.21+/-0.02 mag One should be cautious that the brightness mentioned above may be contaminated by the host. 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/44284. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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