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[vsnet-grb-info 40745] LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42681 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources DATE: 25/11/14 15:15:33 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> K.L. Page (U. Leicester), P.A. Evans (U. Leicester), J.A. Kennea (PSU), A. Tohuvavohu (Cosmic Frontier Labs), S.B. Cenko (NASA/GSFC), R.A.J. Eyles-Ferris (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL), S. Campana (INAF-OAB), J.J. Delaunay (PSU), M. De Pasquale (University of Messina), S. Dichiara (PSU), P. D’Avanzo (INAF-OAB), A. D’Aì (INAF-IASFPA) , V. D’Elia (ASI-SSDC & INAF-OAR), C. Gronwall (PSU), D. Hartmann (Clemson University), N. Klingler (NASA-GSFC / UMBC / CRESST II), N.P.M. Kuin (UCL-MSSL), S. Laha (NASA/GSFC), S.R. Oates (U. Birmingham), J.P. Osborne (U. Leicester), P. O’Brien (U. Leicester), M.J. Page (UCL-MSSL), G. Raman (PSU) S. Ronchini (PSU), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (U Tor Vergata, INAF) report on behalf of the Swift team: Swift has carried out 105 observations of the LVK error region for the GW trigger S251112cm convolved with the 2MPZ catalogue (Bilicki et al. 2014, ApJS, 210, 9), using the 'BAYESTAR' (version BAYESTAR.fits.gz) GW localisation map. As this is a 3D skymap, galaxy distances were taken into account in selecting which ones to observe. The observations currently span from 7.6 ks to 117 ks after the LVK trigger, and the XRT has covered 12.7 deg^2 on the sky (corrected for overlaps). This covers 1.3% of the probability in the 'BAYESTAR' (version BAYESTAR.fits.gz) skymap, and 20% after convolving with the 2MPZ galaxy catalogue, as described by Evans et al. (2016, MNRAS, 462, 1591). We have detected 20 X-ray sources. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at https://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 7 sources of rank 3 * 13 sources of rank 4 RANK 3 sources ============== These are uncatalogued X-ray sources, however they are not brighter than previous upper limits, so do not stand out as likely counterparts to the GW trigger. | Source ID | RA | Dec | Err90 | Detection Flag | | S251112cm_X1 | 11 09 55.90 | +36 08 20.7 | 8.0" | POOR | | S251112cm_X38 | 23 47 03.18 | -28 07 08.2 | 9.5" | POOR | | S251112cm_X53 | 11 08 18.65 | +36 11 04.6 | 8.1" | POOR | | S251112cm_X72 | 12 22 09.27 | +55 52 20.4 | 5.9" | GOOD | | S251112cm_X73 | 01 08 29.26 | -46 59 48.1 | 8.9" | POOR | | S251112cm_X78 | 23 48 35.23 | -28 14 05.5 | 9.8" | POOR | | S251112cm_X79 | 23 48 06.04 | -28 04 35.1 | 12.3" | POOR | RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. | Source ID | RA | Dec | Err90 | Detection Flag | | S251112cm_X2 | 11 12 06.93 | +35 27 45.6 | 6.8" | GOOD | | S251112cm_X3 | 09 20 46.26 | -08 03 21.4 | 5.5" | GOOD | | S251112cm_X5 | 23 51 37.99 | -28 18 18.1 | 7.6" | POOR | | S251112cm_X50 | 11 37 24.49 | +47 27 44.7 | 7.4" | GOOD | | S251112cm_X51 | 01 08 20.79 | -47 07 36.3 | 7.4" | POOR | | S251112cm_X52 | 01 07 42.60 | -46 54 24.5 | 6.1" | GOOD | | S251112cm_X67 | 11 11 04.66 | +35 13 59.3 | 6.9" | GOOD | | S251112cm_X68 | 22 44 47.97 | -00 06 17.5 | 8.8" | GOOD | | S251112cm_X69 | 02 36 19.70 | -54 51 50.8 | 5.8" | GOOD | | S251112cm_X70 | 13 06 57.05 | +59 58 48.1 | 10.7" | REASONABLE | | S251112cm_X71 | 12 23 00.00 | +55 40 04.4 | 5.1" | GOOD | | S251112cm_X87 | 11 12 01.25 | +37 58 26.3 | 6.1" | GOOD | | S251112cm_X88 | 11 04 27.52 | +38 12 36.6 | 3.5" | GOOD | 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 automated analysis, including details of the sources listed above, are online at https://www.swift.ac.uk/LVC/S251112cm This circular is an official product of the Swift XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42681. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40744] IPN triangulation of GRB 251108C
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42680 SUBJECT: IPN triangulation of GRB 251108C DATE: 25/11/14 13:10:56 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, E. Burns on behalf of the IPN, G. Waratkar, J.Joshi, V. Bhalerao, D. Bhattacharya, A. Arya, and S. Vadawale, on behalf of the Astrosat-CZTI team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 251108C (AstroSat-CZTI detection: Salunke et al., GCN 42664) was detected by Konus-Wind, AstroSat (CZTI), and Mars-Odyssey (HEND), at about 83275 s UT (23:07:55). We have triangulated it to a preliminary, 3 sigma error box whose area is 2.13 sq. deg, and its maximum dimension is 40 deg (the minimum one is 5 arcmin). The Sun distance was ~155 deg. This localization may be improved. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB251108_T83283/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/42680. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40743] The EP-WXT trigger 01709248221 is likely a flaring star
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42679 SUBJECT: The EP-WXT trigger 01709248221 is likely a flaring star DATE: 25/11/14 12:33:49 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Z. H. Yang, Q. C. Zhao, Z. X. Li, G. L. Huang, J. Y. Cao (IHEP), J. P. Chen (SYSU), Y. J. Yi (BNU), H. Q. Cheng, H. Sun (NAO, CAS), on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709248221 at the time of 2025-11-14T11:16:43, is likely a stellar flare associated with EM* LkCa 4. The estimated flux of the flare is around 8e-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 1.6e+32 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/42679. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40742] Fermi GRB 251114A: Global MASTER-Net observations report
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42678 SUBJECT: Fermi GRB 251114A: Global MASTER-Net observations report DATE: 25/11/14 03:15:50 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 251114A ( Fermi GBM team, GCN 42676) errorbox 101 sec after notice time and 138 sec after trigger time at 2025-11-14 01:15:30 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 60 deg. The sun altitude is -24.0 deg. The galactic latitude b = -22 deg., longitude l = 57 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3041842 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 154 | 2025-11-14 01:15:30 | MASTER-OAFA | (20h 55m 15.88s , +05d 45m 40.4s) | C | 30 | 19.5 | 190 | 2025-11-14 01:16:06 | MASTER-OAFA | (20h 55m 15.85s , +05d 45m 40.8s) | C | 30 | 19.6 | 231 | 2025-11-14 01:16:41 | MASTER-OAFA | (20h 55m 15.85s , +05d 45m 41.1s) | C | 40 | 19.7 | 282 | 2025-11-14 01:17:28 | MASTER-OAFA | (20h 55m 15.83s , +05d 45m 41.5s) | C | 50 | 19.8 | 343 | 2025-11-14 01:18:24 | MASTER-OAFA | (20h 55m 15.83s , +05d 45m 42.1s) | C | 60 | 19.9 | 648 | 2025-11-14 01:22:59 | MASTER-OAFA | (20h 52m 07.43s , +09d 10m 19.0s) | C | 120 | 19.9 | 784 | 2025-11-14 01:25:05 | MASTER-OAFA | (20h 52m 07.40s , +09d 10m 19.6s) | C | 140 | 20.0 | 947 | 2025-11-14 01:27:33 | MASTER-OAFA | (20h 52m 07.36s , +09d 10m 20.0s) | C | 170 | 20.0 | 1068 | 2025-11-14 01:30:29 | MASTER-OAFA | (20h 52m 07.34s , +09d 10m 20.1s) | C | 60 | 19.6 | 1134 | 2025-11-14 01:31:35 | MASTER-OAFA | (20h 52m 07.33s , +09d 10m 20.0s) | C | 60 | 19.6 | 1200 | 2025-11-14 01:32:41 | MASTER-OAFA | (20h 52m 07.32s , +09d 10m 20.4s) | C | 60 | 19.5 | 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/42678. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40741] LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42677 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility DATE: 25/11/14 02:20:19 GMT FROM: Shreya Anand <shreyasahasram08(a)gmail.com> S. Anand (Stanford), R. Stein (UMD), X. J. Hall (CMU), V. Swain (IIT-B), A. Saikia (IIT-B), T. Mohan (IIT-B), V. Bhalerao (IIT-B), D. Cook (Caltech/IPAC), A. Singh (SU), M. M. Kasliwal (Caltech), E. C. Bellm (UW), M. Coughlin (UMN), T. du Laz (Caltech), V. Karambelkar (Columbia), G. Waratkar (Caltech), I. Andreoni (UNC), A. Palmese (CMU) report, on behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: We observed the localization region of the LVK sub-solar mass candidate S251112cm (GCN 42650) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-11-12 09:21 UTC, approximately 18 hours after merger, covering 38.3% of the probability within the 90% credible region of the LVK skymap in g- and r-bands. This estimate accounts for chip gaps. Each exposure was 300s with a median r-band depth of 21.14 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019), removing candidates with history of variability prior to the merger time. Because of the nature of the GW trigger as a sub-solar mass merger candidate, we do not exclude any candidates that may be consistent with being young stripped envelope supernovae (SESNe). Disk fragmentation or core fissioning in SESNe may lead to the formation of subsolar mass neutron stars (Metzger et al. 2024, Kasliwal et al. 2025). After filtering, 8 transient candidates remain, all within the 95.0% localization of the skymap. Candidates marked as FAR have redshifts from Legacy Survey or from SDSS (shown below). Redshift lower limits come from Legacy Survey (l95; a conservative lower limit on the photometric redshift). We list the 8 candidates found in the table below: | ZTF Name | RA (deg) | DEC (deg) | MJD | Filt | Mag | MagErr | Redshift | Note | | ------------- | ---------- | --------- | -------- | ---- | ----- | ------ | --------------------------------------- | ---------------------------------------- | | ZTF25aceekrn* | 180.101460 | 49.047764 | 60992.43 | g | 21.04 | 0.22 | photo-z=0.14 (LS); photo-z=0.189 (SDSS) | FAR | | ZTF25aceekwp | 181.804049 | 55.653636 | 60992.44 | g | 21.23 | 0.20 | photo-z>0.24 (LS) | FAR | | ZTF25aceelgz | 190.811137 | 57.328886 | 60992.47 | g | 21.15 | 0.13 | spec-z=0.476 (SDSS) | AGN-like; w1-w2=0.97 | | ZTF25aceelbm | 169.544486 | 41.094776 | 60992.41 | g | 21.20 | 0.23 | photo-z=0.21 (LS); photo-z=0.24 (SDSS) | FAR | | ZTF25aceemla | 185.395941 | 56.586289 | 60992.46 | r | 21.25 | 0.23 | photo-z>0.28 (LS) | FAR | | ZTF25aceekzz | 169.076786 | 39.863435 | 60992.41 | g | 21.32 | 0.26 | photo-z=0.528 (LS) | AGN-like; ZTF pre-detections; w1-w2=1.13 | | ZTF25aceelmh | 184.916369 | 57.167778 | 60992.47 | g | 21.61 | 0.22 | photo-z>0.41 (LS); photo-z=0.42 (SDSS) | FAR | | ZTF25aceempu | 169.569004 | 35.985827 | 60992.49 | r | 21.60 | 0.21 | photo-z>0.23 (LS) | FAR | *ZTF25aceekrn (AT 2025adht) was previously reported by the TROVE team (GCN 42675) with a photo-z=0.11 +/- 0.07 (nominally consistent with the LVK distance posterior). A spectrum can help resolve this discrepancy. None of the other candidates reported here warrant additional follow-up. All candidates have been reported to the Transient Name Server, and some are pending assignment of a TNS name. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan; Operations are conducted by Caltech's Optical Observatory (COO) and Caltech/IPAC. GROWTH acknowledges the generous support of the NSF under PIRE Grant No 1545949. Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). The GROWTH India Telescope (GIT, Kumar et al., 2022) is set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. Its operations are partially supported by funding from the IIT Bombay alumni batch of 1994. The Fritz and SkyPortal projects acknowledge the generous support of The Gordon and Betty Moore Foundation. View this GCN Circular online at https://gcn.nasa.gov/circulars/42677. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40740] GRB 251114A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42676 SUBJECT: GRB 251114A: Fermi GBM Final Real-time Localization DATE: 25/11/14 01:23:52 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 01:13:11 UT on 14 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251114A (trigger 784775596.257482 / 251114051). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 312.9, Dec = 9.0 (J2000 degrees, equivalent to J2000 20h 51m, 9d 00'), with a statistical uncertainty of 4.2 degrees. The angle from the Fermi LAT boresight is 82.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114051/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114051/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114051/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42676. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40739] LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42675 SUBJECT: LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates DATE: 25/11/13 22:30:11 GMT FROM: Noah Franz at University of Arizona/Steward Observatory <noahfranz13(a)gmail.com> N. Franz (U. Arizona), N. Vieira (Northwestern), C. D. Kilpatrick (Northwestern), D. J. Sand (U. Arizona), B. Subrayan (U. Arizona), G. Hosseinzadeh (UC San Diego), M. Shrestha (Monash U), K. D. Alexander (U. Arizona), W. Fong (Northwestern), report on behalf of the TROVE collaboration: We analyzed candidate counterparts to the LIGO/Virgo/KAGRA (LVK) gravitational wave event S251112cm (GCN 42650) using the Multi-messenger Tool for Rapid Object Vetting and Examination (TROVE). We searched within the 95th percentile localization region for candidate optical counterparts in host galaxies at the approximate luminosity distance of S251112cm. We further crossmatch to minor planet and point source catalogs and rule out sources that do not appear photometrically similar to kilonova light curves. For additional details, see the vetting procedures described in N. Franz, et al., 2025, arXiv:2510.17104. Below, we report all candidates that remain viable after running our vetting procedure using publicly available information on all publicly reported sources, to date, on the Transient Name Server (TNS). We include their TNS identifier, coordinates, cumulative probability at the coordinate location in the latest LVK map, most likely host redshift, most recent magnitude, and the initial reporting group. Candidates are ranked using a scoring procedure designed to identify kilonova counterparts to GW events (N. Franz, et al., 2025, arXiv:2510.17104). The reported candidates are not clearly identified as kilonovae, but we note that the progenitor system of S251112cm is poorly constrained given the exceptional attributes of the event as reported by LIGO: a probability of the system containing a neutron star < 8%, probability of containing a sub-solar mass object >99%, and a chirp mass in the range 0.1 to 0.87 solar masses. | TNS Name | RA [HMS] | Dec [DMS] | Localization Probability Contour | Most likely Host-z | Most recent public magnitude | Discovery Survey | Comments | | ------- | ------ | ------- | ------- | ------- | ------- | ------- | ------- | | AT2025adht | 12:00:24.350 |+49:02:51.95 | 0.83 | 0.11 +/- 0.07 (photo-z) | g=21.4 +/- 0.2 | ZTF | | | AT2025adgp | 01:47:46.202 | -51:49:25.52 | 0.20 | 0.06 +/- 0.02 (photo-z) | o=19.1 +/- 0.05 | BlackGEM | ATLAS pre-detection ~6 hours before S251112cm. This candidate was initially presented in GCN42663 and the ATLAS pre-detections were noted in GCN 42666. | | AT2025adhf | 02:43:44.411 | -55:19:06.44 | 0.15 | 0.11 +/- 0.02 (photo-z) | o=19.22 +/- 0.05 | ATLAS | ATLAS pre-detections in the ~week leading up to S251112cm. | | AT2025adhs | 04:12:56.396 | -54:11:46.41 | 0.09 | 0.04 (spec-z) | o=20.71 +/- 0.22 | BlackGEM | | We encourage additional follow up of these candidates to determine whether they remain viable counterparts to S251112cm. We note that there are 10 other transients reported to the TNS in the 95% localization region that we rule out for other reasons (e.g., excessive pre-detections, incorrect host distance as compared to S251112cm, etc.): AT2025adhj, AT2025addc, AT2025adhr, AT2025adhu, AT2025adhg, AT2025addb, AT2025adhh, AT2025adda, AT2025adhe, AT2025adgq. View this GCN Circular online at https://gcn.nasa.gov/circulars/42675. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40738] LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42674 SUBJECT: LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region DATE: 25/11/13 20:12:23 GMT FROM: Julius Gassert at Ludwig-Maximilians-Universität München <julius.gassert(a)campus.lmu.de> Julius Gassert (CMU/LMU), Malte Busmann (LMU), Xander J. Hall (CMU), Brendan O’Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report: We observed a sample of 19 DESI galaxies, ranked by 3D position and brightness following the methodology laid out in Hall et al. (2025), in the sky localization region of gravitational wave event S251112cm (GCN 42650) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J bands simultaneously. Observations started at 2025-11-12T17:43 (UT). Typical three-sigma limits for point sources are r, i ~ 21, and the field of view is 7’x7’. We do not identify any candidate GW counterpart in difference imaging with respect to Legacy Survey and PS1 data. The coordinates of the observed targets are listed below. | R.A. | dec | |---|---| | 164.426910134 | 37.65453732955 | | 165.5240393492 | 38.78722513647 | | 167.4811243685 | 36.94655132258 | | 173.5605908567 | 49.0431665104 | | 182.4385674509 | 56.52359456357 | | 182.8894005861 | 57.73745323273 | | 186.0084874694 | 58.38519262405 | | 196.9032263873 | 60.15719529696 | | 197.1937364898 | 62.27166824173 | | 250.834423606 | 70.63254712505 | | 341.1015299287 | -0.162034769873 | | 341.5808358893 | 3.210042314846 | | 343.2053071078 | 1.201113639068 | | 344.2120066199 | -8.967554297055 | | 344.5092848207 | -3.76968999454 | | 345.0369565289 | -12.80783236183 | | 346.7423345683 | -9.286127524436 | | 347.1867614296 | -12.63952485965 | | 349.7190055484 | -10.25928200595 | We thank Christoph Ries from the Wendelstein Observatory staff for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42674. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40737] Fermi GRB 251113A: Global MASTER-Net observations report
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42673 SUBJECT: Fermi GRB 251113A: Global MASTER-Net observations report DATE: 25/11/13 18:46:05 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 251113A ( Fermi GBM team, GCN 42671) errorbox 3189 sec after notice time and 3223 sec after trigger time at 2025-11-13 18:31:13 UT, with upper limit up to 18.9 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -15.3 deg. The galactic latitude b = -35 deg., longitude l = 179 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3041542 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3254 | 2025-11-13 18:31:13 | MASTER-SAAO | (03h 38m 31.68s , +07d 50m 32.6s) | C | 60 | 18.0 | 3314 | 2025-11-13 18:31:13 | MASTER-SAAO | (03h 38m 31.68s , +07d 50m 32.6s) | C | 180 | 18.8 | Coadd 3254 | 2025-11-13 18:31:13 | MASTER-SAAO | (03h 36m 49.82s , +08d 06m 25.7s) | C | 60 | 17.6 | 3345 | 2025-11-13 18:32:45 | MASTER-SAAO | (03h 38m 31.92s , +07d 48m 57.6s) | C | 60 | 18.2 | 3345 | 2025-11-13 18:32:45 | MASTER-SAAO | (03h 36m 50.05s , +08d 04m 49.4s) | C | 60 | 17.7 | 3438 | 2025-11-13 18:34:17 | MASTER-SAAO | (03h 38m 35.46s , +07d 50m 09.7s) | C | 60 | 18.2 | 3438 | 2025-11-13 18:34:18 | MASTER-SAAO | (03h 36m 53.59s , +08d 06m 00.6s) | C | 60 | 17.8 | 3560 | 2025-11-13 18:35:50 | MASTER-SAAO | (03h 38m 30.08s , +07d 49m 40.0s) | C | 120 | 18.8 | 3560 | 2025-11-13 18:35:50 | MASTER-SAAO | (03h 36m 48.15s , +08d 05m 30.5s) | C | 120 | 18.2 | 3713 | 2025-11-13 18:38:23 | MASTER-SAAO | (03h 38m 29.14s , +07d 50m 41.1s) | C | 120 | 18.9 | 3713 | 2025-11-13 18:38:23 | MASTER-SAAO | (03h 36m 47.11s , +08d 06m 30.9s) | C | 120 | 18.5 | 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/42673. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40736] GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42672 SUBJECT: GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734) DATE: 25/11/13 18:19:45 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 784748255 at 17:37:30 on 13 Nov. 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 52.6 deg Decl.(2000.0) = 10.4 deg The 1 sigma statistical error radius is 1.6 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB251113734/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251113734/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251113734/json View this GCN Circular online at https://gcn.nasa.gov/circulars/42672. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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