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[vsnet-grb-info 42419] GRB 260414A: Glowbug gamma-ray detection
by GCN Circulars 14 Apr '26

14 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44297 SUBJECT: GRB 260414A: Glowbug gamma-ray detection DATE: 26/04/14 23:14:50 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 260414A, which was detected by Fermi/GBM (GCN 44293). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-04-14 06:31:55.248 with a duration of 21.5 s and a total significance of about 21 sigma. The detection occurred during a time of high background as Glowbug was entering the northern radiation belt. The brightest peaks in the light curve are at ~T0+3.5s and ~T0+12.5s. 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/44297. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42418] EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
by GCN Circulars 14 Apr '26

14 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44296 SUBJECT: EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope DATE: 26/04/14 17:44:51 GMT FROM: Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197(a)gmail.com> V. Karambelkar, K. De (Columbia University), G. Mo (Carnegie/Caltech), S. Ibrahim, D. Schiminovich (Columbia University) We observed the field of the fast X-ray transient EP260409a (Jiang et al. 2026, GCN 44240) using the MDM InfraRed Astronomy inGaas Explorer (MIRAGE) instrument on the MDM 1.3m telescope in the near-infrared J and Hs bands. Observations were carried out starting at UTC 2026-04-09T03:10:30 in the J-band and 2026-04-09T03:40:58 in the H-band, approximately three hours after the EP trigger. The exposures lasted for a total of 16 minutes in the J-band and 32 minutes in the H-band. We do not detect the counterpart reported by Quirola-Vasquez et al., GCN 44264 to 5-sigma limits of J >~ 19.5 mag (AB) Hs >~ 19.8 mag (AB) MIRAGE is a new YJHs-band near-infrared imager for the MDM 1.3m telescope. We thank the MDM Observatory staff for supporting the observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/44296. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42417] EP260321a: CMO SAI J,K observations
by GCN Circulars 14 Apr '26

14 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44295 SUBJECT: EP260321a: CMO SAI J,K observations DATE: 26/04/14 11:27:29 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A.A. Volnova (IKI), A.M. Tatarnikov (SAI MSU), S.G. Zheltoukhov (SAI MSU), A.S. Pozanenko (IKI), N.S. Pankov (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the fast X-Ray transient EP260321a (Huang et al., GCNs 44068, 44075) at z = 0.0343 (Tanvir et al., GCN 44082) with SAI-2.5 (2.5m) telescope of the Caucasian Mountain Observatory of Sternberg Astronomical Institute (CMO SAI), equipped with the IR camera ASTRONIRCAM. The observations in the J and K filters were carried out on 2026-04-02, and in J filter on 2026-04-07. The Supernova reported previously (Lee et al., GCN 44070; Ma et al., GCN 44074; Aguilar-Ruiz et al., GCN 44076; Liang et al., GCN 44079; Aryan et al., GCN 44081; 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; Li et al., GCN 44284) is clearly detected in stacked frames. Preliminary photometry and observational details are the following: Date UT_start t-T0 Exp. Filter Obj. Err. UL Site/Telescope (mid,days) (n*s) (3sigma) 2026-04-02 21:11:47 12.36569 6*96 J 16.76 0.04 20.5 CMO SAI/SAI-2.5 2026-04-02 20:58:27 12.35698 20*29 K 16.50 0.06 19.1 CMO SAI/SAI-2.5 2026-04-07 17:53:10 17.23089 11*96 J 16.45 0.04 21.1 CMO SAI/SAI-2.5 The photometry is based on several nearby stars from the 2MASS-PSC and is not corrected for the Galactic extinction. The supernova continues to rise in the J-band and is most likely near the maximum of the SN light curve. View this GCN Circular online at https://gcn.nasa.gov/circulars/44295. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42416] GRB 260412A: Insight-HXMT/HE detection
by GCN Circulars 14 Apr '26

14 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44294 SUBJECT: GRB 260412A: Insight-HXMT/HE detection DATE: 26/04/14 07:29:11 GMT FROM: Xinghao Luo at IHEP <2952704891(a)qq.com> Xing-Hao Luo, Chen-Wei Wang, Chao Zheng, Cheng-Kui Li and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2026-04-12T06:13:46.169 (T0), Insight-HXMT/HE detected the burst GRB 260412A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #44275), SVOM/ECLAIRs(Ziqi Wang et.al., GCN#44276) and GECAM-B(Xing-Hao Luo.et.al., GCN#44281). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 40 +4/-6 s. The 1s peak rate, measured from T0+23 s, is 1028 cnts/sec. Insight-HXMT/HE detected a total of 9203 counts from this burst. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb260412A.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/44294. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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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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