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[vsnet-grb-info 40786] LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42722 SUBJECT: LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results DATE: 25/11/17 15:38:01 GMT FROM: Zhengyan Liu at USTC <ustclzy(a)mail.ustc.edu.cn> Z. Y. Liu, W. Zhao, J.-A. Jiang, Z. L. Xu, D. Z. Meng, M. X. Cai, T. G. Wang, X. Kong, Z. G. Dai, L. L. Fan (USTC), Z. P. Jin, Y. Z. Fan (PMO) report on behalf of the WFST Collaboration: Following the detection of the sub-solar mass merger candidate S251112cm (the LIGO-Virgo-Kagra Collaboration, GCN 42650), we conducted follow-up observations focused on the northern region of the initial bayestar skymap (GCN 42650) using the newly deployed 2.5-meter Wide Field Survey Telescope (WFST Collaboration; Wang et al., 2023) at the Lenghu Astronomical Observation Base (Qinghai province, China). Observations began at UTC 2025-11-13T11:29:36, corresponding to ~20.2 hours after the merger event (UTC 2025-11-12T15:18:45). The follow-ups lasted for three nights until UTC 2025-11-15T23:16:16. We observed in WFST g, r, and i bands with exposure times of 45-90 seconds. A total area of about 727.4 square degrees of the 90% skymap (GCN 42650) was observed, covering ~64% of the event localization. Additionally, ~7.5% skymap was covered in 30s g- and r-band exposures through the WFST wide-field survey (WFS) 6.35 hours after the merger event. The follow-up observation data were processed using the WFST pipeline. For images localized in WFS, image subtraction was performed using the WFST stacking images taken berfore the event as templates. The search for the counterpart of S251112cm was performed mainly through visual inspection based on the locations of nearby galaxies, considering the distance estimate of 93 +/- 27 Mpc (redshift ~ 0.02; the LIGO-Virgo-Kagra Collaboration, GCN 42690) and the uncertainty of the potential electromagnetic counterpart. All extragalactic transient candidates detected by WFST during follow-ups were reported to the IAU Transient Name Server (TNS). After excluding sources with pre-merger detections reported in TNS, only one candidate was found to be located near a galaxy with spectroscopic redshift below 0.045: AT2025aebp was first detected at 60992.93 (+1.3 days post-merger) with 21.5 +/- 0.1 mag in r-band, and the spectroscopic redshift of its possible host galaxy SDSS J103703.20+231142.2 is 0.043. Additionally, we report three other sources without pre-merger detections. These sources have possible host galaxies with SDSS DR16 photometric redshift (Csabai et al., 2007; Ahumada et al., 2019) less than 0.1: | AT Name | MJD | RA | Dec | Filter | Mag | Host | photoZ | |------------|-----------|----------|----------|--------|----------|--------------------------|------------| | AT2025aebk | 60992.86 | 156.5043 | 24.9277 | g | 21.8 ± 0.1 | SDSS J102601.47+245542.1 | 0.06 ± 0.02 | | AT2025aebl | 60992.92 | 152.3554 | 18.2025 | r | 21.4 ± 0.1 | SDSS J100925.32+181207.3 | 0.09 ± 0.03 | | AT2025aebq | 60992.94 | 172.3128 | 36.6438 | r | 21.4 ± 0.1 | SDSS J112914.78+363832.0 | 0.09 ± 0.03 | We also checked the aforementioned candidates reported through TNS and GCN Circulars (GCN 42658, GCN 42666, GCN 42677, GCN 42691, GCN 42707). Ten public sources were detected in our difference images. Difference photometric results are listed as follows: | AT Name | MJD | RA | Dec | Filter | Mag | |------------|-----------|----------|----------|--------|------------| | AT2025adjd | 60992.96 | 190.8110 | 56.8036 | r | 21.31 ± 0.04 | | AT2025adie | 60992.83 | 185.3958 | 56.5862 | g | 21.7 ± 0.1 | | AT2025adhu | 60992.83 | 181.8041 | 55.6536 | g | 21.4 ± 0.1 | | AT2025adtj | 60990.94 | 172.5489 | 38.6207 | r | 19.64 ± 0.03 | | AT2025adia | 60992.85 | 169.5689 | 35.9858 | g | 21.6 ± 0.1 | | AT2025adln | 60989.89 | 168.0373 | 30.42659 | g | 21.2 ± 0.2 | | AT2025adlk | 60989.93 | 159.2667 | 19.30616 | g | 20.1 ± 0.1 | | AT2025adic | 60989.89 | 169.5444 | 41.0946 | g | 21.8 ± 0.2 | | AT2025adtq | 60990.94 | 175.6142 | 34.0085 | r | 21.2 ± 0.1 | | AT2025adtk | 60990.93 | 174.3825 | 31.3606 | r | 18.98 ± 0.02 | We thank the WFST staff for supporting these observations. Subsequent WFST observations and a systematic search for potential transients are ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/42722. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40785] GRB 251116C: Swift-XRT observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42721 SUBJECT: GRB 251116C: Swift-XRT observations DATE: 25/11/17 15:30:14 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 251116C, collecting 1.7 ks of Photon Counting (PC) mode data between T0+10 ks and T0+26 ks after the trigger. We have detected 2 sources. These have been automatically classified as follows: * 0 likely counterparts * 0 candidate counterparts * 2 uncatalogued X-ray sources * 0 known X-ray sources Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J222122.5-102045): ================================== RA (J2000.0): 335.3441 = 22 21 22.58 Dec (J2000.0): -10.3459 = -10 20 45.2 Error: 6.9 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 6.1 arcmin from the SVOM/ECLAIRs position. Mean rate: (7.3 [+3.1, -2.5])e-3 ct s^-1 Mean flux: (4.4 [+1.9, -1.5])e-13 erg cm^-2 s^-1 Peak rate: (7.3 [+3.1, -2.5])e-3 ct s^-1 Peak flux: (4.4 [+1.9, -1.5])e-13 erg cm^-2 s^-1 ECF: 6.06e-11 erg cm^-2 ct^-1 assuming NH=4.81e+20 cm^-2, gamma=0.94 determined from a spectral fit. XMM UL: 4.1e-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. There is 1 2MASS object within the source's 3-sigma error radius. Source 2 (SWIFT J222052.1-102849): ================================== RA (J2000.0): 335.2172 = 22 20 52.13 Dec (J2000.0): -10.4803 = -10 28 49.1 Error: 5.8 (arcsec, radius, 90% confidence). Detect flag: POOR Distance: 5.1 arcmin from the SVOM/ECLAIRs position. Mean rate: (-1.0 +/- -1.0)e0 ct s^-1 Mean flux: (-4.3 +/- -4.3)e-11 erg cm^-2 s^-1 Peak rate: (2.4 [+1.9, -1.3])e-3 ct s^-1 Peak flux: (1.03 [+0.80, -0.57])e-13 erg cm^-2 s^-1 XMM UL: 4.7e-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. 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_FIELD00051. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42721. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40784] LIGO/Virgo/KAGRA S251116en: Updated Sky localization
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42720 SUBJECT: LIGO/Virgo/KAGRA S251116en: Updated Sky localization DATE: 25/11/17 14:29:45 GMT FROM: Colm Talbot at Princeton University <talbotcolm(a)gmail.com> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S251116en (GCN Circular 42708). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251116en For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 792 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1928 +/- 496 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] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42720. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40783] GRB 251117A: Fermi GBM Final Localization Correction
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42719 SUBJECT: GRB 251117A: Fermi GBM Final Localization Correction DATE: 25/11/17 13:55:50 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> The Fermi GBM team reports the detection of a likely SHORT GRB. At 12:19:52.14 UT on 17 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251117A (trigger 785074797/251117514). This trigger was initially classified as Below horizon by the flight software, but is in fact due to a GRB. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 335.05, Dec = 5.01 (J2000 degrees, equivalent to J2000 22h 20m, +05d 00'), with a statistical uncertainty of 4.40 degrees. The angle from the Fermi LAT boresight is 52 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42719. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[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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