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

[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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[vsnet-grb-info 41509] GRB 260114A: VLT/HAWK-I near-infrared upper limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43414 SUBJECT: GRB 260114A: VLT/HAWK-I near-infrared upper limits DATE: 26/01/15 14:29:46 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata <yyang(a)roma2.infn.it> Yu-Han Yang, Muskan Yadav, Massine El Kabir, Niccolò Passaleva, Eleonora Troja, and Hira Waseem (U Rome) report: We observed the field of GRB 260114A, detected by Swift (Eyles-Ferris et al., GCN 43396), Fermi (Fermi GBM Team, GCN 43395; E. Bissaldi et al. GCN 43400), GECAM-B (Ren et al., GCN 43402) and SVOM/GBM (SVOM/GRM team, GCN 43404) and Konus-Wind (Ridnaia et al., GCN 43413) with the HAWKI imager on the ESO VLT UT4 (Yepun). Observations began 14.2 hours after the trigger and were carried out in the J and Ks filters at an average airmass of 1.0. Within the XRT source position (Beardmore et al., GCN 43412) several catalogued objects are visible in our images, however no obvious counterpart is detected down to a 3-sigma limit Ks>24 AB mag, calibrated using nearby stars in the 2MASS Catalog (Skrutskie et al. 2006). Additional observations to assess variability are planned. We thank the staff at the VLT for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/43414. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41508] Konus-Wind detection of GRB 260114A
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43413 SUBJECT: Konus-Wind detection of GRB 260114A DATE: 26/01/15 12:44:01 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The short-duration GRB 260114A (Fermi-GBM detection: Fermi GBM Team, GCN 43395; Bissaldi, GCN 43400; Swift-BAT detection: Eyles-Ferris et al., GCN 43396; GECAM-B observation: Ren et al., GCN 43402; SVOM/GRM observation: Wang et al., GCN 43404) triggered Konus-Wind at T0=42030.729 s UT (11:40:30.729). The burst light curve shows a single pulse which starts at ~T0 s and has a total duration of ~0.3 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260114_T42030/ As observed by Konus-Wind, the burst had a fluence of 5.12(-0.25,+0.25)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.024 s, of 2.76(-0.33,+0.33)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = 0.56(-0.15,+0.16) and Ep = 502(-25,+26) keV (chi2 = 36/34 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.4 (chi2 = 36/33 dof). Assuming the redshift z=0.524 (Yang et al., GCN 43410) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 3.86(-0.19,+0.19)x10^51 erg, the peak luminosity L_iso is 3.17(-0.38,+0.38)x10^52 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is 765(-38,+40) keV. With the obtained estimates, the position of GRB 260114A in both Eiso-Ep,z and Liso-Ep,z planes is consistent with short-hard (Type I) GRB population, see http://www.ioffe.ru/LEA/GRBs/GRB260114_T42030/GRB260114A_rest_frame.pdf All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/43413. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41507] GRB 260114A: Swift-XRT refined Analysis
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43412 SUBJECT: GRB 260114A: Swift-XRT refined Analysis DATE: 26/01/15 11:55:38 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), S. Lanava (PSU), J.P. Osborne (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 4.9 ks of XRT data for GRB 260114A, from 107 s to 33.3 ks after the trigger. The data comprise 9 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 74.59789, -8.01441 which is equivalent to: RA (J2000): 04h 58m 23.49s Dec(J2000): -08d 00' 51.9" with an uncertainty of 3.2 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=2.9 (NaN, NaN). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.7 (+0.8, -0.6). The best-fitting absorption column is 4.9 (+8.1, -3.9) x 10^21 cm^-2, in excess of the Galactic value of 5.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.9 x 10^-11 (6.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.9 (+8.1, -3.9) x 10^21 cm^-2 Galactic foreground: 5.7 x 10^20 cm^-2 Excess significance: 1.9 sigma Photon index: 1.7 (+0.8, -0.6) If the light curve continues to decay with a power-law decay index of 2.9, the count rate at T+24 hours will be 1.2 x 10^-8 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.9 x 10^-19 (8.2 x 10^-19) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01440319. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43412. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41506] GRB 260114A: 6 GHz VLA observations
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43411 SUBJECT: GRB 260114A: 6 GHz VLA observations DATE: 26/01/15 11:11:29 GMT FROM: Roberto Ricci at INAF-IRA <ricci(a)ira.inaf.it> R. Ricci, M. Yadav, E. Troja (U Rome) report: We observed the short-duration GRB 260114A detected by Fermi-GBM (Fermi team GCN 43395), Swift/BAT (Eyles-Ferris et al. GCN 43396), GECAM-B (Ren et al., GCN 43402) and SVOM/GBM (SVOM/GRM team, GCN 43404) with Very Large Array in C-band at the centre frequency of 6 GHz with a bandwidth of 4 GHz on Jan 15th 2025, 15.5 hours after the burst. After reducing the data using the CASA version v6.6.1 with standard procedures no source was detected inside the Swift/XRT error circle (Eyles-Ferris et al., GCN 43396) down to a 3-sigma flux density upper limit of about 30 microJy/beam. We thank the VLA staff for promptly executing the observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/43411. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41505] GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43410 SUBJECT: GRB 260114A: VLT/X-shooter redshift of the putative host galaxy DATE: 26/01/15 09:07:12 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata <yyang(a)roma2.infn.it> Yu-Han Yang (U Rome), Eleonora Troja (U Rome), and Rosa Becerra (UNAM) report: We observed the field of GRB 260114A, detected by Swift (Eyles-Ferris et al., GCN 43396), Fermi (Fermi GBM Team, GCN 43395; E. Bissaldi et al. GCN 43400), GECAM-B (Ren et al., GCN 43402) and SVOM/GBM (SVOM/GRM team, GCN 43404), with the X-Shooter spectrograph on the ESO VLT UT3 (Melipal). Observations started at 13.8 hours after the GRB trigger, with a total exposure time of 4 × 600 s at an average airmass of ~1.1. In the acquisition image no new uncatalogued source is detected. Several extended sources, also reported in the DESI Legacy Survey, are visible within the XRT error circle. For the brightest object with r~21.1 AB mag we derive a chance alignment of P_cc ~ 4%. Based on a preliminary analysis, we identify multiple emission features corresponding to Hα, Hβ, and the [O II] doublet with a common redshift of z~0.524. We thank the staff at the VLT, especially T. Rivinius and L. Sbordone, for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/43410. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41504] GRB 260114A : MITSuME Akeno optical upper limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43409 SUBJECT: GRB 260114A : MITSuME Akeno optical upper limits DATE: 26/01/15 06:59:47 GMT FROM: Ichiro Takahashi at Science Tokyo <itakahashi(a)hp.phys.titech.ac.jp> I. Takahashi, M. Sasada, H. Hagio, A. Ochi, Y. Kubo, R. Kato, H. Seki, S. Joshima, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration: We observed the field of GRB 260114A detected by Fermi (Fermi GBM team, GCN 43395) and Swift (Eyles-Ferris et al., GCN 43396) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. The observation started at 2026-01-14 11:41:18 UT (52 seconds after the trigger). We stacked the images taken under good conditions. We did not detect any obvious point sources within the Swift/XRT error region (Eyles-Ferris et al., GCN 43396). We obtained the 5-sigma limits of the stacked images as follows: T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits ------------------------------------------------------------------------------------------------ 228 | 2026-01-14 11:44:14 | 140 | g'>17.5, Rc>17.5, Ic>17.2 4089 | 2026-01-14 12:48:35 | 4260 | g'>19.8, Rc>19.9, Ic>19.5 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the trigger T-EXP: Total exposure time We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire) View this GCN Circular online at https://gcn.nasa.gov/circulars/43409. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41503] GRB 260114A: COLIBRÍ optical upper limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43408 SUBJECT: GRB 260114A: COLIBRÍ optical upper limits DATE: 26/01/15 04:42:41 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo(a)astro.unam.mx> Camila Angulo (UNAM), Jean-Grégoire Ducoin (CPPM), Rosa L. Becerra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the Swift GRB 260114A (Eyles-Ferris et al., GCN Circ. 43396), also detected by Fermi (Fermi GBM Team, GCN Circ. 43395; E. Bissaldi et al. GCN Circ. 43400), GECAM-B (Ren et al., GCN Circ. 43402), SVOM/GBM (SVOM/GRM team, GCN Circ. 43404), using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-15 02:01 to 03:22 UTC (from 14.3 to 15.7 hours after the trigger) and obtained 63 minutes of simultaneous exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ ASU pipeline and analysed with STDWeb (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. After performing image subtraction of our stacked images against Legacy Survey (Dey et al. 2019) using STDWeb (Karpov 2025), we do not detect any new source at the XRT source position (Eyles-Ferris et al., GCN Circ. 43396) or the optical counterpart previously reported by GMG (Li et al., GCN Circ. 43398) and the Mondy observatory (Volnova et al., GCN Circ. 43401) down to the following 3-sigma limits: r > 24.1, z > 22.7. These upper limits are consistent with later reports from MASTER (Lipunov et al., GCN Circ. 43403), NOT (Corcoran et al., GCN Circ. 43406) and TNG (Brivio et al., GCN Circ. 43407). We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/43408. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41502] GRB 260114A: TNG NIR upper limit
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43407 SUBJECT: GRB 260114A: TNG NIR upper limit DATE: 26/01/15 01:04:21 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, P. D'Avanzo (INAF-OAB), D. B. Malesani (DAWN/NBI & Radboud Univ.), L. Izzo (INAF-OACn), A. Melandri (INAF-OAR), M. Pedani (INAF-TNG) report on behalf of the CIBO collaboration: We observed the field of GRB 260114A detected by Fermi/GBM (Fermi GBM team, GCN 43395), Swift/BAT (Eyles-Ferris et al., GCN 43396), GECAM-B (Ren et al., GCN 43402), and SVOM/GRM (Wang et al., GCN 43404) with the Italian 3.6m TNG telescope, located in the Canary Islands (Spain), equipped with the near-infrared camera NICS in imaging mode. A series of images were obtained with the H filter on 2026-01-14 at a mid-time of about 10.0 hours after the burst. The optical counterpart reported by Li et al. (GCN 43398) and Volnova et al. (GCN 43401) is not detected within the Swift/XRT error circle. We obtain a 3-sigma limiting magnitude of H > 20.6 (Vega; calibrated against the 2MASS catalogue). View this GCN Circular online at https://gcn.nasa.gov/circulars/43407. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41501] GRB 260114A: NOT optical observations
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43406 SUBJECT: GRB 260114A: NOT optical observations DATE: 26/01/14 21:40:44 GMT FROM: Gregory Corcoran at University College Dublin <gregory.corcoran(a)ucdconnect.ie> G. Corcoran (UCD), A. Martin-Carrillo (UCD), A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), K. Valeckas (NOT & NBI) report on behalf of a larger collaboration: We observed the field of GRB 260114A detected by Fermi/GBM (Fermi GBM team, GCN 43395), Swift/BAT (Eyles-Ferris et al., GCN 43396), GECAM-B (Ren et al., GCN 43402), and SVOM/GRM (Wang et al., GCN 43404) with the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Our observations consisted of 8 x 300 s exposures in SDSS-r and 5 x 200 s in SDSS-z, starting on Jan 14 2026 at 19:32:39 UT (7.87 hr after the trigger). After performing image subtraction against Legacy Survey using PyZOGY on the stacked images, we do not detect the optical counterpart reported by Li et al. (GCN 43398) and Volnova et al. (GCN 43401) within the Swift/XRT uncertainty region. We obtain the following 3 sigma upper limits in AB magnitudes: r > 24.0 (mid-time of 8.66 hr after the trigger) z > 22.2 (mid-time of 8.30 hr after the trigger) calibrated against nearby stars from the Pan-STARRS catalog, and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43406. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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