November 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 40782] GRB 251116D: Glowbug gamma-ray detection
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42718 SUBJECT: GRB 251116D: Glowbug gamma-ray detection DATE: 25/11/17 13:07:33 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 251116D, which was also detected by AstroSat/CZTI and Konus-Wind (GCN 42715). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-16 19:22:33.960 with a duration of 14.3 s and a total significance of about 60 sigma. The light curve comprises a primary peak at ~T0+2s, followed by a multi-peaked structure for the duration of the burst. The best-fit localization is RA, Decl. (J2000, deg) = 148.0, -37.6 with a radius of 3.7 deg (95% confidence), with a highly uncertain systematic uncertainty. 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/42718. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40781] EP251023a: Assy AZT-20 optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42717 SUBJECT: EP251023a: Assy AZT-20 optical observations DATE: 25/11/17 13:07:17 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), M. Krugov (FAI) report on behalf of IKI-GRB-FuN: We observed the field of the EP transient EP251023a (Wu et al., GCN 42388) in r' filter with the AZT-20 1.5m telescope of Assy-Turgen observatory starting on Oct., 23, 2025 (UT) 20:25:35, taking several exposures of 60 seconds. The optical counterpart (Wortley et al., GCN 42387; Li et al., GCN 42389; Liu et al., GCN 42391; Mandarakas et al., GCN 42400; Lipunov et al., GCN 42405; Selezneva et al., GCN 42406; Mohan et al., GCN 42411; Rakotondrainibe et al., GCN 42420; Rajabov et al., GCN 42422; Volnova et al., GCN 42468; Volnova et al., GCN 42716) is clearly detected in the stacked frame. The preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-10-23 20:25:35 0.76378 30*60 r' 20.22 0.06 22.2 The photometry is based on several nearby PS1 stars (AB-system) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42717. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40780] EP251023a: ISON/UAFO and AbAO optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42716 SUBJECT: EP251023a: ISON/UAFO and AbAO optical observations DATE: 25/11/17 12:54:12 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), A. Kochergin (UAFO), R. Ya. Inasaridze (AbAO) report on behalf of IKI-GRB-FuN: We observed the field of the EP transient EP251023a (Wu et al., GCN 42388) with the RC-500 (0.5m) telescope of UAFO/ISON-Ussuriysk observatory on Oct., 23, 2025 starting at (UT) 17:51:51, and the AS-32 0.7m telescope of the Abastumani Observatory (AbAO) on Oct., 24, 2025, starting at (UT) 22:53:36. Several 60-second exposures in R-filter were obtained during each observational epoch. The optical counterpart (Wortley et al., GCN 42387; Li et al., GCN 42389; Liu et al., GCN 42391; Mandarakas et al., GCN 42400; Lipunov et al., GCN 42405; Selezneva et al., GCN 42406; Mohan et al., GCN 42411; Rakotondrainibe et al., GCN 42420; Rajabov et al., GCN 42422; Volnova et al., GCN 42468) is clearly detected in the stacked UAFO image and is not detected in that of the AbAO. The preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL Site/Tel. (mid,days) (n*s) (3sigma) 2025-10-23 17:51:51 0.67889 100*60 R 19.97 0.22 20.9 UAFO/RC-500 2025-10-24 22:53:36 1.88138 40*60 R n/d n/d 20.5 AbAO/AS-32 The photometry is based on several nearby PS1 stars (Lupton's R-band transformation, Vega system) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42716. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40779] GRB 251116D: AstroSat CZTI detection
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42715 SUBJECT: GRB 251116D: AstroSat CZTI detection DATE: 25/11/17 10:04:03 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> Harsha K. H. (IUCAA), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), A. Goyal (IITB), A. Arya (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 251116D which was also detected by Konus Wind (IPN Notices). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-11-16 19:22:37.50 UTC. The measured peak count rate associated with the burst is 472 (+45, -48) counts/s above the background in the combined data of all quadrants, with a total of 2912 (+187, -203) counts. The local mean background count rate was 283 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 12.4 (+1.5, -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 showed multiple peaks of emission with the strongest peak at 2025-11-16 19:22:36.63 UTC. The measured peak count rate associated with the burst is 1074 (+80, -86) counts/s above the background in the combined data of all quadrants, with a total of 4561 (+353, -380) counts. The local mean background count rate was 1330 (+6, -7) counts/s. We measure a T90 of 12.0 (+1.0, -1.4) 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/42715. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40778] LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42714 SUBJECT: LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations DATE: 25/11/17 09:58:25 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. Y. Wu, J. W. Hu, Y. Liu (NAO, CAS), B. Zhang (HKU) on behalf of the Einstein Probe (EP) team: EP-FXT performed a series of follow-up observations of the LIGO/Virgo/KAGRA gravitational-wave event S251112cm (GCN 42650, GCN 42690), with 100 galaxy-targeted observations have been completed. These observations were conducted from 2025-11-12T15:38:36 to 2025-11-14T10:28:28 (UTC), with each pointing having an exposure of approximately 300 s. EP-FXT covered 88 deg2 (8.9% in probability) of the updated sky localization area (GCN 42690) We cross-matched all FXT detections from these pointings against the updated list of NED galaxies provided in GCN 42693, using a 100″ matching radius (for a galaxy at 100 Mpc this corresponds to an offset of ~50 kpc). Most matched sources have prior X-ray detections with FXT fluxes comparable to historical values. There are two weak sources without prior X-ray counterparts within the FXT error region. Their information is summarized below (RA/Dec in degrees with 10" error radius (90% C.L.); fluxes are the observed ones in 0.5–10 keV): Name | RA | Dec | Matched NED Galaxy | Sep. (arcsec) | Flux (erg/s/cm^2) | SNR ---------------------------------------------------------------------------------------------------------------------------- EPF_J234847.8-282639 | 357.1990 | -28.4442 | WISEA J234841.30-282641.1 | 85.2 | 7.4e-13| 6.6 EPF_J010845.7-463304 | 17.1904 | -46.5512 | SMDG J0108452-463428 | 83.8 | 1.4e-13| 4.2 In addition, FXT detected 8 sources with no prior X-ray detections, no matches to the NED galaxies and no obvious AGN or stellar counterparts within the FXT error regions. Their information is summarized below (RA/Dec in degrees with 10" error radius (90% C.L.); fluxes are the observed ones in 0.5–10 keV): Name | RA | Dec | Flux (erg/s/cm^2) | SNR ------------------------------------------------------------------------- EPF_J000245.6-341925 | 0.6899 | -34.3235 | 2.0e-13| 4.0 EPF_J020544.2-520424 | 31.4343 | -52.0734 | 1.7e-13| 4.1 EPF_J092041.9-081815 | 140.1746 | -8.3041 | 2.1e-13| 4.9 EPF_J093255.2-020027 | 143.2301 | -2.0076 | 4.3e-13| 3.5 EPF_J111043.0+362227 | 167.6792 | 36.3742 | 1.6e-13| 4.6 EPF_J113825.2+432218 | 174.6051 | 43.3716 | 7.3e-14| 5.4 EPF_J232328.1-114600 | 350.8670 | -11.7667 | 1.5e-13| 3.9 EPF_J234628.3-290057 | 356.6177 | -29.0158 | 7.9e-13| 4.5 Further FXT observations of these candidates will be conducted. 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/42714. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40777] The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42713 SUBJECT: The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations DATE: 25/11/17 09:56:34 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the EP-WXT trigger 01709247588 (Feng et al., GCN 42510) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in the R-filter starting Oct., 29, 2025, UT 16:48:48, and taking several frames with 120 s exposures. The Emission-line Star PM J04472+2038 likely associated with the transient is clearly detected and not saturated. Preliminary photometry and observational details are the following: Date UT start MJD Exp. Filter Star Err. UL (mid) (n*s) (3sigma) 2025-10-29 16:48:48 60977.71098 15*120 R 13.25 0.08 22.2 The photometry is based on several nearby USNO-B1.0 stars (R2-magnitudes) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. The star PM J04472+2038 is at least 0.4 mag brighter in our observations comparing to USNO-B1.0 and UCAC catalogues: UCAC R = 13.99 +/- 0.09, USNO-B1.0 R1 = 13.65, R2 = 14.07. This 0.4m brightness increase 5.5 hours after the EP-WXT trigger may confirm the connection between EP-WXT 01709247588 and the stellar flare. View this GCN Circular online at https://gcn.nasa.gov/circulars/42713. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40776] GRB 251116C: SVOM/VT optical upperlimit
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42712 SUBJECT: GRB 251116C: SVOM/VT optical upperlimit DATE: 25/11/17 09:39:51 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, Y. Xu, X. H. Han, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM) report on behalf of the SVOM/VT team. SVOM/VT performed an automatic slew on GRB 251116C (SVOM burst-id sb25111605, Pillas et al., GCN 42703). The observation started on 2025-11-16T17:04:52 UT (i.e. 1.1 hour post trigger) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources are detected in single or stacked images within ECL's error box (Pillas et al., GCN 42703) and the Swift/XRT source #1 and source #2's error box (https://www.swift.ac.uk/SVOM/SVOM_FIELD00051/) The 3 sigma limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 1.4 hour VT_B 23*50 sec >23.3 mag 1.4 hour VT_R 28*50 sec >23.4 mag Our result is consistent with the LCO's observation (Turpin et al., GCN 42705). 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/42712. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40775] GRB 251025B: further Mondy optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42711 SUBJECT: GRB 251025B: further Mondy optical observations DATE: 25/11/17 08:08:51 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We continued observations of the field of the GRB 251025B (Hussein et al., GCN 42437) in the R-filter with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) taking several frames with 120 s exposures on Oct. 27-29 and Nov. 1, 2025. The optical counterpart (Wu et al., GCN 42438; Gress et al., GCN 42439; Wu et al., GCN 42440; Beardmore et al., GCN 42445; Mohan et al., GCN 42447; Hernández Funget al., GCN 42450; Pereyra et al., GCN 42452; Li et al., GCN 42453; Mo et al., GCN 42459; Rakotondrainibe et al., GCN 42460; Rajabov et al., GCN 42466; Saccardi et al., GCN 42472; Freeberg et al., GCN 42474; Volnova et al., GCN 42475; Gupta et al., GCN 42500; Mohan et al., GCN 42503; Adami et al., GCN 42547) is clearly detected in the stacked frame of every epoch. Preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-20-27 15:53:18 2.08280 30*120 R 21.22 0.07 22.8 2025-10-28 16:11:51 3.11396 29*120 R 21.82 0.17 22.3 2025-10-29 15:14:24 4.03841 5*120 R 21.95 0.25 22.2 2025-11-01 15:12:37 7.07680 60*120 R 22.94 0.26 23.2 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/42711. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40774] GRB 251111A: Mondy optical upper limit
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42710 SUBJECT: GRB 251111A: Mondy optical upper limit DATE: 25/11/17 08:05:29 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the GRB 251111A (Cheng et al., GCN 42637) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in the R-filter starting Nov., 11, 2025, UT 16:26:22, and taking several frames with 120 s exposures. In the stacked frame we do not detect the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCNs 42639, 42641; Ma et al., GCN 42647). Preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-11-11 16:26:22 0.48686 25*120 R n/d n/d 22.1 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/42710. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40773] GRB 251116B: EP-FXT follow-up observation
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42709 SUBJECT: GRB 251116B: EP-FXT follow-up observation DATE: 25/11/17 03:44:02 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D.Y. Li, G. J. Yang, C. L. Guo (NAO, CAS), D. Z. Du (ZJU), R. X. Hu (WHU), Q. J. Huang(PMO, CAS), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 251116B (SVOM/sb25111604, Pillas et al., GCN #42702) at 2025-11-16 17:13:25 (UTC), about 1.7 hours after the SVOM/ECLAIRs trigger, with an exposure time of 5832s. Six uncataloged sources are detected within the ECLAIRs error circle. Preliminary analysis on these sources is automatically conducted, and the details are listed as follows. EPF_J011551.9-410700 RA (J2000): 18.9664 Dec (J2000): -41.1167 Flux: 5.54 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.68 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011518.5-405816 RA (J2000): 18.8272 Dec (J2000): -40.971 Flux: 1.35 x 10^-13 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 4.97 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011442.3-410511 RA (J2000): 18.6761 Dec (J2000): -41.0863 Flux: 4.54 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.58 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011604.1-410246 RA (J2000): 19.0172 Dec (J2000): -41.0461 Flux: 6.74 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.73 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011523.3-410250 RA (J2000): 18.8471 Dec (J2000): -41.0471 Flux: 6.72 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 2.29 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011535.7-410502 RA (J2000): 18.8988 Dec (J2000): -41.0839 Flux: 7.66 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.59x 10^-14 erg/s/cm2 (1 sigma) View this GCN Circular online at https://gcn.nasa.gov/circulars/42709. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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