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

[vsnet-grb-info 40715] GRB251111A: 1.3m DFOT optical upper limit
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42651 SUBJECT: GRB251111A: 1.3m DFOT optical upper limit DATE: 25/11/12 16:45:38 GMT FROM: ANSHIKA GUPTA at ARIES <anshika05180(a)gmail.com> Anshika Gupta, Kumar Pranshu, Debolina Kar, Dhruv Jain, Pankaj Pawar and Kuntal Misra (ARIES) report: We observed the field of GRB251111A detected by SVOM (Cheng et al. 2025, GCN 42637), with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2025-11-11 at 15:37:41 UT, i.e., ~10.45 hours after the SVOM trigger. We have taken multiple frames with an exposure time of 300 s in the R filter. We stacked the images after the alignment. We could not detect the optical emission in our stacked image within the error box of SVOM/COLIBRÍ (López-Cámara et al. 2025, GCN 42638) & Swift-XRT (Campana et al. 2025, GCN 42648). We obtain the following 3-sigma upper limit in the stacked image: Date Start_UT T_start-T0 (hour) Filter Exp time (s) Magnitude =============================================================== 2025-11-11 15:37:41 ~10.45 R 300s*24 >23.2 The upper limit of the burst is consistent with López-Cámara et al. 2025 (GCN 42638); Wu et al. 2025 (GCN 42639); Zheng et al. 2025 (GCN 42640); Wu et al. 2025 (GCN 42641); Ma et al. 2025 (GCN 42647). The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue. View this GCN Circular online at https://gcn.nasa.gov/circulars/42651. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40714] LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42650 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate DATE: 25/11/12 15:55:25 GMT FROM: Alicia Calafat <alicia.calafat(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251112cm during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-11-12 15:18:45.362 UTC (GPS time: 1446995943.362). The candidate was found by the MBTA SSM [1] analysis pipeline. S251112cm is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.1e-09 Hz, or about one in 6 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251112cm The analysis which found this candidate used a template bank including sub-solar-mass components. The usual classification probabilities for BNS, NSBH, or BBH binaries versus Terrestrial noise are not calculated for this candidate. The probability of matter remaining outside the final compact object (HasRemnant) [2] is not estimated either. Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass between 1 and 3 solar masses (HasNS) is 8%. [2] The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The probability that the lighter compact object is below 1 solar mass (HasSSM) is >99%. The source chirp mass falls with highest probability in the bin (0.1, 0.87) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [3], distributed via GCN and SCiMMA notices about 57 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [3], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 1220 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 96 +/- 29 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [3] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42650. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40713] GRB 251106B: Glowbug gamma-ray detection of a likely short burst
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42649 SUBJECT: GRB 251106B: Glowbug gamma-ray detection of a likely short burst DATE: 25/11/12 15:46:47 GMT FROM: richard.s.woolf.civ(a)us.navy.mil R. Woolf, C.C. Cheung, 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 251106B, which was also detected by SVOM/GRM (GCN 42612) and Insight-HXMT/HE (GCN 42633). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-06 18:14:42.936 with a duration of 1.02 s and a total significance of about 7.3 sigma. The light curve comprises two primary peaks within 1-s duration. Note that data from ~T0 to T0+2.2s and ~T0+3s to T0+5.2s suffered from deadtime in various detectors. 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/42649. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40712] GRB 251111A: Swift-XRT afterglow detection
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42648 SUBJECT: GRB 251111A: Swift-XRT afterglow detection DATE: 25/11/12 10:51:12 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Campana (INAF-OAB), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of GRB 251111A. We searched for X-ray sources in 2.1 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 2.1 ks, obtained between T0+7.6 ks and T0+36.9 ks. An uncatalogued X-ray source is detected and is believed to be the afterglow. Using 305 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 32.36166, +5.22815 which is equivalent to: RA (J2000): 02h 09m 26.80s Dec(J2000): +05d 13' 41.3" with an uncertainty of 5.1 arcsec (radius, 90% confidence). The observed count rate was 2.5 (+1.2, -0.9)e-02 count/s at T0+7.7 ks, falling to 5.2 (+2.6, -1.9)e-03 at T0+33.8 ks, which indicates the X-ray source is fading. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/03000189. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00049. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42648. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40711] GRB 251111A: SVOM/VT optical observations with X-band data
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42647 SUBJECT: GRB 251111A: SVOM/VT optical observations with X-band data DATE: 25/11/12 07:32:30 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma, H. L. Li, L. P. Xin, 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 (NAOC), J. Palmerio (CEA), Y. H. Cheng (SWIFAR, YNU), B. T. Wang(YNAO) report on behalf of the SVOM/VT team. SVOM/VT performed an automatic slew on the burst GRB 251111A (sb25111101) triggered by SVOM/ECLAIRs (Cheng et al., GCN 42637). SVOM/VT began observing the field at 2025-11-11 06:01:57 UTC, 51.656 minutes after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With X-band data available, the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCN 42639; Zheng et al., GCN 42640; Wu et al., GCN 42641) was detected in VT_R band within XRT's error box (Evans et al., GCN 42645) and EP-FXT's error box (Cheng et al., GCN 42643) at the mid time of 1.34 hour, followed with a decay slope of -0.7. The measurements are: mid time (h) | exposure time (s) | band | mag (AB) -------------|-------------------|------|---------------- 1.34 | 28*50 | VT_R | 22.3+/-0.2 6.10 | 14*100 | VT_R | 23.5+/-0.3 Data analysis is on going. Our photometry was not corrected for Galactic extinction. 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/42647. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40710] SVOM GRB251111.42: Global MASTER-Net observations report
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42646 SUBJECT: SVOM GRB251111.42: Global MASTER-Net observations report DATE: 25/11/11 15:28:29 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-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the SVOM GRB251111.42 (trigger No 1762855221,21h 58m 08.11s , -32d 32m 58.9s, R=1) errorbox 17209 sec after notice time and 17236 sec after trigger time at 2025-11-11 14:47:37 UT, with upper limit up to 16.2 mag. Observations started at twilight. The observations began at zenith distance = 76 deg. The sun altitude is -10.6 deg. The galactic latitude b = -53 deg., longitude l = 14 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3038591 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 17327 | 2025-11-11 14:47:37 | MASTER-Kislovodsk | (21h 55m 21.98s , -32d 13m 40.7s) | C | 180 | 15.8 | 17327 | 2025-11-11 14:47:37 | MASTER-Kislovodsk | (22h 00m 17.67s , -32d 36m 56.7s) | C | 180 | 16.2 | 17468 | 2025-11-11 14:50:58 | MASTER-Kislovodsk | (22h 00m 08.74s , -32d 41m 52.6s) | C | 60 | 15.6 | 17468 | 2025-11-11 14:50:58 | MASTER-Kislovodsk | (22h 05m 05.54s , -33d 05m 13.1s) | C | 60 | 16.2 | 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/42646. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40709] GRB 251111A: Swift-XRT observations
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42645 SUBJECT: GRB 251111A: Swift-XRT observations DATE: 25/11/11 14:02:01 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source GRB 251111A, collecting 288 s of Photon Counting (PC) mode data between T0+7.4 ks and T0+7.8 ks after the trigger. We have detected 1 source. This has been automatically classified as an uncatalogued X-ray source. Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J020926.8+051342): ================================== RA (J2000.0): 32.3618 = 02 09 26.83 Dec (J2000.0): +5.2284 = +05 13 42.2 Error: 5.7 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 2.0 arcmin from the SVOM/ECLAIRs position. Mean rate: 0.0264 [+0.0127, -0.0096] ct s^-1 Mean flux: (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1 Peak rate: 0.0264 [+0.0127, -0.0096] ct s^-1 Peak flux: (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1 ECF: 2.73e-11 erg cm^-2 ct^-1 assuming NH=5.07e+20 cm^-2, gamma=2.63 determined from a spectral fit. XMM UL: 2.6e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. The XRT position is consistent the optical counterpart reported by the SVOM/COLIBRÍ (FM-GFT; López-Cámara et al., GCN Circ. 42638), LCO 1m (Wu et al., GCN Circ. 42639) and SVOM/VT (Wu et al., GCN 42641) telescopes, as well as the Einstein Probe FXT X-ray detection (Cheng et al. 42643). All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00049. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42645. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40708] SVOM GRB251111.22: Global MASTER-Net observations report
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42644 SUBJECT: SVOM GRB251111.22: Global MASTER-Net observations report DATE: 25/11/11 13:28:25 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-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the SVOM GRB251111.22 (trigger No 1762837816,02h 09m 30.79s , +05d 15m 24.1s, R=0.1259) errorbox 28018 sec after notice time and 28619 sec after trigger time at 2025-11-11 13:07:15 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 58 deg. The sun altitude is -34.8 deg. The galactic latitude b = -52 deg., longitude l = 157 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3038098 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 28650 | 2025-11-11 13:07:15 | MASTER- | (02h 09m 32.85s , +04d 36m 16.3s) | C | 60 | 19.8 | 28650 | 2025-11-11 13:07:15 | MASTER-Tunka | (02h 09m 14.02s , +04d 42m 25.1s) | C | 60 | 19.9 | 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/42644. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40707] GRB 251111A: EP-FXT counterpart detection
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42643 SUBJECT: GRB 251111A: EP-FXT counterpart detection DATE: 25/11/11 13:12:22 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.H. Cheng (SWIFAR,YNU), Z. M. Wang (BNU), Y. J. Zhang (THU), C. L. Guo, J. W. Hu, 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 251111A (SVOM/sb25111101, Cheng et al., GCN #42637) at 2025-11-11 06:06:55 (UTC), about 0.93 hours after the SVOM/ECLAIRs trigger, with an exposure time of 1939 s. One uncatalogued source is detected within the ECLAIRs error circle, and the source is spatially consistent with the counterpart reported in optical band (López-Cámara et al., GCN #42638; Wu et al., GCN #42639, Zheng et al., GCN #42640, Wu et al., GCN #42641). Preliminary analysis on this source is automatically conducted, and the details are listed as follows. Source 1 ：EPF_J020926.9+051342 RA (J2000): 32.362 Dec (J2000): 5.228 Flux: 1.24 x 10^-12 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 3.53 x 10^-13 erg/s/cm2 (1 sigma) The position uncertainty of the source is about 10 arcsec in radius (90% C.L. statistical and systematic). 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/42643. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40706] GRB 251013C: Chandra X-ray observations and jet break detection
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42642 SUBJECT: GRB 251013C: Chandra X-ray observations and jet break detection DATE: 25/11/11 10:50:45 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo(a)ucd.ie> A. Martin-Carrillo (UCD), B. P. Gompertz (Birmingham), D. B. Malesani (DAWN/NBI and Radboud), report on behalf of a larger collaboration: We observed the afterglow of GRB 251013C (Fermi GBM team, GCN 42221; Rakotondrainibe et al., GCN 42222) with the Chandra X-ray Observatory starting on 2025-11-09 at 03:09:42 UT (i.e., T0+27.396 d, observer frame), for a total of 40 ks exposure, in response to our DDT request (PI A. Martin-Carrillo, ObsID 31983). A faint X-ray source is detected at a location consistent with that of the afterglow (Palmerio et al., GCN 42223; Laskar et al., GCN 42243). Assuming a spectrum model consistent with the one measured by Swift/XRT (Evans et al., GCN 42232; https://www.swift.ac.uk/xrt_spectra/03000137/) we infer a flux in the 0.3-10 keV energy range of ~2.5e-15 erg s^-1 cm^-2. This late Chandra observation implies that the source has undergone significant steepening in its X-ray flux decay when compared with the earlier Swift/XRT and EP/FXT observations (Evans et al., GCN 42232; Wang et al., GCN 42247), suggesting a jet break sometime between 6 and 10 days since trigger in the observer frame. We thank the entire CXO team for the rapid evaluation and scheduling of our observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42642. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0