January 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 41519] EP260116a: Einstein Probe detection of an X-ray transient
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43424 SUBJECT: EP260116a: Einstein Probe detection of an X-ray transient DATE: 26/01/16 12:01:43 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> C. Wang, Z. X. Li, G. L. Huang, J. Y. Cao (IHEP), Y. H. Jiang (NJU), Z. X. Ling (NAOC) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260116a. A significant outburst is observed in the WXT light curve. The transient triggered EP-WXT (ID: 01709251336) at 2026-01-16T00:08:51 (UTC). The WXT position of the source is R.A. = 113.768 deg, DEC = 6.329 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The average WXT 0.5 - 4 keV spectrum can be fitted with an absorbed power law with a hydrogen column density of 7.65 x 10^20 cm^-2 and a photon index of 1.77. The derived average unabsorbed 0.5-4 keV flux is 7.16 x 10^-11 erg/s/cm^2. A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically with a 24-minute delay, starting at 2026-01-16 00:32:38 (UTC), by which time the outburst had already ended. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 113.7617 deg, DEC = 6.3244 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). The average FXT 0.5 - 10.0 keV spectra can also be fitted with an absorbed power law with the same hydrogen column density and a photon index of 1.98. The derived average unabsorbed 0.5-10.0 keV flux is 9.52 x 10^-14 erg/s/cm^2. 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/43424. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41518] GRB 260114A: VLT/HAWK-I near-infrared upper limits
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43423 SUBJECT: GRB 260114A: VLT/HAWK-I near-infrared upper limits DATE: 26/01/16 11:26:08 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> B. Schneider (LAM), D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), M. De Pasquale (Univ. Messina), H. Fausey (Baylor), B. P. Gompertz (Birmingham), A. J. Levan (Radboud and Warwick), R. Z. Li (Yunnan), A. Martin-Carrillo (UCD), G. Pugliese (API), A. Rossi (INAF-OAS), N. R. Tanvir (Leicester), A. L. Thakur (INAF-IAPS), S. D. Vergani (LUX-Paris Obs.) report on behalf of the Stargate collaboration: We observed the field of the short GRB 260114A (Eyles-Ferris et al., GCN 43396; Bissaldi, GCN 43400; Ren et al., GCN 43402; Wang et al., GCN 43404; Ridnaia et al., GCN 43413) using the ESO/VLT UT4 equipped with the HAWK-I instrument. Observations were carried out over two nights, with mean epochs Jan 15.06 and 16.05UT (13.8 and 37.6 hr after the trigger, respectively), both in the H band, with an exposure time of 30 min each. No new sources are detected consistent with the Swift/XRT position, except for two (possibly three) objects (Li et al., GCN 43398) visible in the Legacy survey, one of which is a galaxy at z = 0.524 (Yang et al., GCN 43410). Image subtraction between the two epochs was carried out with HOTPANTS (Becker et al. 2015). No source is detected in the difference image down to a limiting magnitude H > 24.2 (AB, 3-sigma). Our non-detection is consistent with the limits provided by Brivio et al. (GCN 43407) and Yang et al. (GCN 43414). We acknowledge excellent support from the observing staff at Paranal, in particular Thomas Rivinius, Julien Drevon, Camila de Sa Freitas, Rodrigo Romero. View this GCN Circular online at https://gcn.nasa.gov/circulars/43423. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41517] IceCube Alert 260115.73: Global MASTER-Net observations report
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43422 SUBJECT: IceCube Alert 260115.73: Global MASTER-Net observations report DATE: 26/01/15 20:13:29 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) started inspect of the IceCube Alert 260115.73 (trigger No 80302474,09h 45m 33.60s , +12d 16m 40.8s, R=1.18) errorbox 9252 sec after notice time and 9296 sec after trigger time at 2026-01-15 20:07:31 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 79 deg. The sun altitude is -24.5 deg. The galactic latitude b = 45 deg., longitude l = 223 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3103091 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9326 | 2026-01-15 20:07:31 | MASTER-SAAO | (09h 40m 55.07s , +12d 14m 34.0s) | C | 60 | 14.4 | 9326 | 2026-01-15 20:07:31 | MASTER-SAAO | (09h 39m 05.66s , +12d 30m 27.4s) | C | 60 | 17.9 | 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/43422. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41516] IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43421 SUBJECT: IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 26/01/15 20:05:03 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 26-01-15 at 17:32:35.71 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 2.0497 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/141917_80302474.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 26-01-15 Time: 17:32:35.71 UT RA: 145.77 (+2.29/-1.77 deg 90% PSF containment) J2000 Dec: 12.41 (+1.18/-0.91 deg 90% PSF containment) J2000 As announced in GCN Circular 43419 (https://gcn.nasa.gov/circulars/43419) the probability distribution of the true neutrino direction, allowing the extraction of precise 90% containment regions around the best-fit direction, is now available. The corresponding link (for this alert https://roc-2.icecube.wisc.edu/public/alerts/IceCube-260115A_skymap_probden…) is provided through the GCN schema distributed via Kafka. IceCube GCN notices for high-energy track alerts (Gold and Bronze) are now also distributed via Kafka and can be accessed through the Kafka topic 'gcn.notices.icecube.gold_bronze_track_alerts'. Further details will be available soon at https://gcn.nasa.gov/missions/icecube. Please note that the classical GCN stream will be deactivated in the near future. No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of this event. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu View this GCN Circular online at https://gcn.nasa.gov/circulars/43421. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41515] GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43420 SUBJECT: GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741) DATE: 26/01/15 19:22:56 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 at 17:46:45 on 15 Jan. 2026 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) = 112.0 deg Decl.(2000.0) = 7.9 deg The 1 sigma statistical error radius is 4.6 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB260115741/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB260115741/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB260115741/json View this GCN Circular online at https://gcn.nasa.gov/circulars/43420. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41514] IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43419 SUBJECT: IceCube: GCN Notices for high-energy track alerts now streamed via Kafka DATE: 26/01/15 19:01:43 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration announces that, starting on IceCube-260115A, IceCube’s real-time GCN Notices for high-energy track alerts (Gold and Bronze alerts) are being streamed via the GCN Kafka system, for both preliminary and revised reconstructions. During an initial transition period, IceCube alerts will be distributed simultaneously through both the classic GCN system (via AMON; https://gcn.gsfc.nasa.gov/amon_icecube_gold_bronze_events.html) and GCN over Kafka. This dual-distribution phase is intended to ensure continuity for existing subscribers while enabling the community to migrate to the new Kafka-based infrastructure. After this transition period, alert dissemination will fully switch to GCN Kafka; a further announcement will follow. The transition to GCN Kafka introduces important new features for IceCube alerts: 1. **Release of multi-order probability sky maps** For each revised alert reconstruction (Revision 1), IceCube now provides a multi-order probability map (MOC/HEALPix; https://gcn.nasa.gov/docs/sample/healpix) describing the directional probability distribution of the neutrino event. These maps were not available through the previous alert system and include both statistical and systematic uncertainties, with probability density expressed in units of 1/sr. 2. **Updated calculation of astrophysical probability and false-alarm rate** With GCN Kafka, the reported astrophysical probability (now denoted *p_astro*, previously referred to as *signalness*) and false-alarm rate (FAR) are recalculated using the revised best-fit event direction provided in the updated reconstruction (associated with the second GCN Notice). In the previous system, these quantities were reported using values from the preliminary reconstruction and were not updated after directional refinement. We encourage all users of IceCube real-time alerts to begin subscribing to the Kafka `topic = gcn.notices.icecube.gold_bronze_track_alerts` IceCube Gold/Bronze alerts now follow [this GCN schema structure](https://github.com/nasa-gcn/gcn-schema/blob/v6.1.0/gcn/notices/i…. Detailed documentation describing the alert distribution, schemas, and probability maps will be available soon at: https://gcn.nasa.gov/missions/icecube Questions regarding IceCube alerts may be directed to the IceCube Collaboration. The IceCube real-time alert point of contact can be reached at roc(a)icecube.wisc.edu. View this GCN Circular online at https://gcn.nasa.gov/circulars/43419. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41513] Fermi GRB 260115A: Global MASTER-Net observations report
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43418 SUBJECT: Fermi GRB 260115A: Global MASTER-Net observations report DATE: 26/01/15 18:45:39 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 Fermi GRB 260115A ( Fermi GBM team, GCN 43417) errorbox 45 sec after notice time and 77 sec after trigger time at 2026-01-15 17:48:03 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 59 deg. The sun altitude is -41.0 deg. MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 260115A errorbox 548 sec after notice time and 580 sec after trigger time at 2026-01-15 17:56:26 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 49 deg. The sun altitude is -59.1 deg. The galactic latitude b = 9 deg., longitude l = 214 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3103145 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 88 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 36m 40.06s , +03d 42m 42.1s) | C | 20 | 17.2 | 113 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 36m 40.06s , +03d 42m 42.1s) | C | 70 | 17.9 | Coadd 88 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 40m 49.00s , +03d 19m 43.0s) | C | 20 | 17.3 | 128 | 2026-01-15 17:48:44 | MASTER-Kislovodsk | (07h 36m 40.13s , +03d 42m 39.9s) | C | 20 | 17.3 | 128 | 2026-01-15 17:48:44 | MASTER-Kislovodsk | (07h 40m 49.04s , +03d 19m 39.7s) | C | 20 | 17.3 | 174 | 2026-01-15 17:49:24 | MASTER-Kislovodsk | (07h 36m 40.22s , +03d 42m 38.6s) | C | 30 | 17.5 | 174 | 2026-01-15 17:49:24 | MASTER-Kislovodsk | (07h 40m 49.10s , +03d 19m 38.3s) | C | 30 | 17.6 | 229 | 2026-01-15 17:50:15 | MASTER-Kislovodsk | (07h 36m 40.26s , +03d 42m 37.7s) | C | 40 | 17.7 | 289 | 2026-01-15 17:50:15 | MASTER-Kislovodsk | (07h 36m 40.26s , +03d 42m 37.7s) | C | 160 | 18.5 | Coadd 295 | 2026-01-15 17:51:15 | MASTER-Kislovodsk | (07h 36m 40.31s , +03d 42m 37.5s) | C | 50 | 17.8 | 295 | 2026-01-15 17:51:15 | MASTER-Kislovodsk | (07h 40m 49.19s , +03d 19m 36.6s) | C | 50 | 18.0 | 385 | 2026-01-15 17:52:36 | MASTER-Kislovodsk | (07h 36m 40.38s , +03d 42m 37.5s) | C | 70 | 18.0 | 391 | 2026-01-15 17:52:42 | MASTER-Kislovodsk | (07h 40m 49.30s , +03d 19m 36.9s) | C | 70 | 18.2 | 611 | 2026-01-15 17:56:26 | MASTER-Tunka | (07h 20m 16.73s , +03d 41m 02.8s) | C | 60 | 19.5 | 611 | 2026-01-15 17:56:26 | MASTER-Tunka | (07h 19m 45.70s , +03d 47m 07.0s) | C | 60 | 19.2 | 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/43418. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41512] GRB 260115A: Fermi GBM Final Real-time Localization
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43417 SUBJECT: GRB 260115A: Fermi GBM Final Real-time Localization DATE: 26/01/15 17:57:28 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 17:46:45 UT on 15 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260115A (trigger 790192010.88085 / 260115741). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.2, Dec = 3.3 (J2000 degrees, equivalent to J2000 07h 20m, 3d 17'), with a statistical uncertainty of 5.1 degrees. The angle from the Fermi LAT boresight is 83.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43417. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41511] GRB260114A: STEP/T80S optical limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43416 SUBJECT: GRB260114A: STEP/T80S optical limits DATE: 26/01/15 16:20:05 GMT FROM: André Santos at Centro Brasileiro de Pesquisas Físicas (CBPF) <andsouzasanttos(a)gmail.com> A. Santos (CBPF), C. R. Bom (CBPF), C. D. Kilpatrick (Northwestern), L. Santana-Silva (CBPF), P. Darc (CBPF/Northwestern), Gabriel Teixeira (CBPF/UCA), C. Mendes de Oliveira (IAG-USP) report on behalf of the STEP collaboration: We conducted optical follow up with the T80S 0.8-m robotic telescope with the S-PLUS Transient Extension Program (STEP; Santos et al., 2024, MNRAS, 529, 59) of the short gamma-ray burst GRB260114A discovered by the Fermi-GBM, Swift-BAT and XRT instruments (GCN 43395,43396). The T80S observations started on Jan 15 03:18:38 UT (~16 hours after the trigger). We obtained images totaling 1200s (6x200s) in i-band with the T80S camera centered at the position reported in the Swift-BAT and XRT report at R.A.=04:58:23.59 and Decl.=-08:00:51.6 (J2000). After subtracting a Pan-STARRS DR2 template image from the T80S coadded frame using photpipe (Rest et al., 2005, ApJ, 634, 1103), we do not detect any transient source in our difference image within the XRT error circle and derive a 3-sigma limiting magnitude of i > 22.4 mag. View this GCN Circular online at https://gcn.nasa.gov/circulars/43416. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41510] GRB 251222A: radio detection with the VLA
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43415 SUBJECT: GRB 251222A: radio detection with the VLA DATE: 26/01/15 15:16:45 GMT FROM: Stefano Giarratana at INAF-OAB <s.giarratana(a)ira.inaf.it> S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.), O. S. Salafia (INAF-OAB), L. Nava (INAF-OAB) At 03:47:54 UT on 2025 December 24 (T_mid = 1.48 days post-burst) the Karl G. Jansky VLA observed the field of GRB 251222A / EP251222B (Fermi GBM team, GCN 43186, 43222; SVOM team, GCN 43188, GCN 43202; Einstein Probe team, GCN 43201, 43215; Konus-Wind team, GCN 43214; GECAM team, GCN 43218) in three bands, with central frequencies of 6, 10 and 15 GHz. The standard 3C48 was used as bandpass and flux density calibrator, while J0501-0159 was used as phase calibrator. From a preliminary analysis, an unresolved radio source is detected at a position (J2000): RA: 05:08:46.775 +- 0.001 Dec: -07:12:48.80 +- 0.02 consistent with the X-ray (SVOM team, GCN 43188, 43202; Einstein Probe team, GCN 43201, 43215; Swift/XRT team, GCN 43213) and optical (SVOM team, GCN 43189, 43203, 43208; An et al., GCN 43194; Calapai et al., GCN 43195; Durbak et al., GCN 43197; Gupta et al., GCN 43207; GOTO collaboration, GCN 43209; Pérez-Fournon et al., GCN 43212; Gupta et al., GCN 43224; Globus et al., GCN 43225; IKI-GRB-FuN team, GCN 43226, 43230, 43273; GRANDMA collaboration, GCN 43229, 43237; Busmann et al., GCN 43233; Lee et al., GCN 43236; Mephisto Team, GCN 43250) position of the transient. The preliminary analysis yields the following results: ================================================================ T_mid Freq Peak r.m.s. Beam PA [days] [GHz] [uJy/b] [uJy/b] [arcsec^2] [deg] ================================================================ 1.48 6 71 7 1.29x0.91 -22 1.48 10 208 8 0.75x0.58 -16 1.48 15 241 8 0.56x0.38 -28 ================================================================ No source is detected with a >3sigma confidence level at the aforementioned position in the VLASS. However, the r.m.s. noise level of the survey at the GRB location is approximately 150 uJy/b. We would like to thank the staff of the VLA for approving, executing, and processing the observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. These observations were carried out as part of project SF181027, approved in the framework of the Fermi - NRAO joint program agreement. View this GCN Circular online at https://gcn.nasa.gov/circulars/43415. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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