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[vsnet-grb-info 41610] GRB 260125B: Fermi GBM Final Real-time Localization
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43511 SUBJECT: GRB 260125B: Fermi GBM Final Real-time Localization DATE: 26/01/25 10:36:26 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 10:25:45 UT on 25 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260125B (trigger 791029550.226442 / 260125435). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 77.1, Dec = 17.6 (J2000 degrees, equivalent to J2000 05h 08m, 17d 36'), with a statistical uncertainty of 11.6 degrees. The angle from the Fermi LAT boresight is 28.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43511. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41609] GRB 260125A: Fermi GBM Final Real-time Localization
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43510 SUBJECT: GRB 260125A: Fermi GBM Final Real-time Localization DATE: 26/01/25 07:47:31 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 07:36:58 UT on 25 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260125A (trigger 791019423.079276 / 260125317). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 148.7, Dec = -2.9 (J2000 degrees, equivalent to J2000 09h 54m, -2d 53'), with a statistical uncertainty of 8.9 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/bn260125317/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125317/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125317/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43510. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41608] GRB 260114A: SVOM/VT optical upper limits
by GCN Circulars 24 Jan '26

24 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43509 SUBJECT: GRB 260114A: SVOM/VT optical upper limits DATE: 26/01/25 04:16:37 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma (NAOC), R. Z. Li (YNAO), L. P. Xin, H. L. Li, Z. H. Yao, Y. L. Qiu, C. Wu, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei, D. H. Zhao (NAOC), J. Palmerio (CEA), B. T. Wang (YNAO), Y. H. Cheng (YNU) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of GRB 260114A detected by Swift/BAT, Fermi/GBM, SVOM/GRM, GECAM-B, Konus-Wind and Insight-HXMT/HE (Fermi GBM Team, GCN 43395; Eyles-Ferris et al., GCN 43396; Bissaldi, GCN 43400; Ren et al., GCN 43402; Wang et al., GCN 43404; Beardmore et al., GCN 43412; Ridnaia et al., GCN 43413; Ren et al., GCN 43503). SVOM/VT began observing the field at 2026-01-14 14:47:02 UTC, 3.11 hours after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. We performed the second observation as a template on January 19th. After performing image subtraction of our stacked images against the second observation, no uncataloged candidate was detected within the error box provided by Swift/XRT position (Beardmore et al., GCN 43412) or the optical counterpart previously reported by GMG (Li et al., GCN Circ. 43398) and the Mondy observatory (Volnova et al., GCN Circ. 43401). The three sigma limits are: mid-time | exposure time | band | upper limit (AB) ----------|-----------------|-------|----------------- 4.241 h | 69*70 sec | VT_B | > 23.8 mag 4.251 h | 67*70 sec | VT_R | > 23.5 mag Our results are consistent with MASTER (Lipunov et al., GCN Circ. 43403), NOT (Corcoran et al., GCN Circ. 43406), TNG (Brivio et al., GCN Circ. 43407), COLIBRÍ (Angulo et al., GCN 43408), MITSuME (Takahashi et al., GCN 43409), VLT (Yang et al., GCN 43414; Schneider et al ., GCN 43423) and Swift/UVOT (Siegel & Eyles-Ferris, GCN 43473). 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/43509. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41607] GRB 260120A: AstroSat CZTI detection
by GCN Circulars 24 Jan '26

24 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43508 SUBJECT: GRB 260120A: AstroSat CZTI detection DATE: 26/01/24 11:33:06 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> Harsha K. H. (IUCAA), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), A. Arya (IITB), A. Goyal (IITB), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260120A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 43467), and GECAM-B (Guo et al., GCN Circ. 43505). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-01-20 04:01:55.50 UTC. The measured peak count rate associated with the burst is 264 (+132, -24) counts/s above the background in the combined data of three quadrants (out of four), with a total of 345 (+83, -77) counts. The local mean background count rate was 189 (+3, -7) counts/s. Using cumulative rates, we measure a T90 of 3.1 (+1.1, -0.8) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-01-20 04:01:54.79 UTC. The measured peak count rate associated with the burst is 246 (+62, -64) counts/s above the background in the combined data of all quadrants, with a total of 625 (+185, -199) counts. The local mean background count rate was 1120 (+5, -6) counts/s. We measure a T90 of 4.2 (+1.3, -1.5) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/43508. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41606] GRB 260122B: Swift-BAT refined analysis
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43507 SUBJECT: GRB 260122B: Swift-BAT refined analysis DATE: 26/01/24 00:54:15 GMT FROM: Amy <yarleen(a)gmail.com> D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), A. Mei (INAF-OAB), M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 260122B (trigger #1443066) (Mei et al., GCN Circ. 43502). The ground analysis confirms that this event is indeed a GRB and not due to background fluctuations (Mei et al., GCN Circ. 43502). The BAT ground-calculated position is RA, Dec = 336.096, -59.176 deg which is RA(J2000) = 22h 24m 22.9s Dec(J2000) = -59d 10' 32.1" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 57%. The mask-weighted light curve shows a single-pulse structure that starts ~T-1 s, peaks at ~T+9 s, and ends at ~T+20 s. T90 (15-350 keV) is 16.59 +- 3.89 sec (estimated error including systematics). The time-averaged spectrum from T+0.23 to T+19.51 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.34 +- 0.17. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+8.46 sec in the 15-150 keV band is 1.6 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1443066 View this GCN Circular online at https://gcn.nasa.gov/circulars/43507. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41605] GRB 260120B: SVOM/GRM observation
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43506 SUBJECT: GRB 260120B: SVOM/GRM observation DATE: 26/01/23 15:57:20 GMT FROM: renyz16607(a)163.com SVOM/GRM team: Yang-Zhao Ren, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot(IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by GRB 260120B at 2026-01-20T18:00:26.200 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #43477) and Swift/BAT (Ferro et al., GCN #43479). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a pulse with a T90 of 8.5 +5.0/-3.5 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260120B.png In addition, the position of this burst, as determined by Swift/BAT (RA = 284.666, Dec = 61.912, GCN #43479), is located at about 89 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0 to T0+5 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.16 +0.16/-0.18 and the cutoff energy, parameterized as Epeak, is 307 +106/-62 keV. The event fluence (10-1000 keV) in this time interval is (3.78 +0.32/-0.33)E-06 erg/cm^2. The localization of GRB 260120B in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260120B_amati.png 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: Yang-Zhao Ren (IHEP)(renyz(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/43506. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41604] GRB 260120A: GECAM-B observation
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43505 SUBJECT: GRB 260120A: GECAM-B observation DATE: 26/01/23 15:39:23 GMT FROM: guohx(a)ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 260120A, at 2026-01-20T04:01:55.800 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43467). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 2.3 +1.1/-0.7 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260120A.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/43505. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41603] GRB 260120B: AstroSat CZTI detection
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43504 SUBJECT: GRB 260120B: AstroSat CZTI detection DATE: 26/01/23 12:52:45 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Goyal (IITB), A. Arya (IITB), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260120B which was also detected by Swift BAT (M. Ferro et. ala, GCN Circ. 43479), Fermi GBM (Fermi GBM Team, GCN Circ. 43477), Swift XRT (Goad et al., GCN Circ. 43484), and SVOM/C-GFT (Wu et al., GCN Circ. 43483). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-01-20 18:00:23.85 UTC. The measured peak count rate associated with the burst is 312 (+129, -23) counts/s above the background in the combined data of three quadrants (out of four), with a total of 622 (+153, -176) counts. The local mean background count rate was 174 (+4, -6) counts/s. Using cumulative rates, we measure a T90 of 5.0 (+1.5, -1.5) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-01-20 18:00:22.68 UTC. The measured peak count rate associated with the burst is 333 (+65, -44) counts/s above the background in the combined data of all quadrants, with a total of 1026 (+266, -251) counts. The local mean background count rate was 1065 (+7, -9) counts/s. We measure a T90 of 4.3 (+1.6, -1.8) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/43504. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41602] GRB 260114A: Insight-HXMT/HE detection
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43503 SUBJECT: GRB 260114A: Insight-HXMT/HE detection DATE: 26/01/23 11:58:54 GMT FROM: renyz16607(a)163.com Yang-Zhao Ren, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team: At 2026-01-14T11:40:26.300 (T0), Insight-HXMT/HE detected a short burst, GRB 260114A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #43395), Swift/BAT (Eyles-Ferris et al., GCN #43396), GECAM-B (Ren et al., GCN #43402), SVOM/GRM (Wang et al., GCN #43404), and Konus-Wind (Ridnaia et al., GCN #43413). The Insight-HXMT/HE light curve mainly consists of multi-pulses with T90 of 0.28 +0.02/-0.02 s. The 1s peak rate, measured from T0-0.09 s, is 3104 cnts/sec. Insight-HXMT/HE detected a total of 3038 counts from this burst. The Insight-HXMT /HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb260114A.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://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/43503. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41601] GRB 260122B: Swift detection of a burst
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43502 SUBJECT: GRB 260122B: Swift detection of a burst DATE: 26/01/22 23:49:28 GMT FROM: Mike Siegel at PSU/Swift MOC <siegel(a)swift.psu.edu> A. Mei (INAF-OAB), R. Brivio (INAF-OAB), R. Gupta (NASA GSFC), A. Y. Lien (U Tampa) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 23:13:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260122B (trigger=1443066). Swift did not slew immediately to the burst due to observing constraint. The BAT on-board calculated location is RA, Dec 336.079, -59.167 which is RA(J2000) = 22h 24m 19s Dec(J2000) = -59d 10' 02" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 15 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. We note that the burst occurred during the high background interval near the SAA. Therefore, at this moment we cannot completely rule out the possibility that the event is due to background fluctuation. However, given that the image significance is 9.35 sigma, we believe this is likely a real burst. Further ground data is required to determine the nature of the burst. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 2026 February 16. There will thus be no XRT or UVOT data for this trigger. Burst Advocate for this burst is A. Mei (alessio.mei AT inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43502. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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