{
  "body": "A. Saccardi (CEA/Irfu), B. Schneider (LAM), J. An (NAOC), D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), S. D. Vergani (LUX-Paris Obs.), A. J. Levan (Radboud and Warwick), N. R. Tanvir (U. Leicester), A. L. Thakur (INAF/IAPS), report on behalf of the Stargate collaboration:\n\nIn light of the early optical upper limits reported by Li et al. (GCN 45539), we observed the field of the SVOM GRB 260909A (Saccardi et al., GCN 45534; Wang et al., GCN 45538) using the ESO VLT UT1 (Antu) equipped with the FORS2 imager and the ESO VLT UT4 (Keyen) equipped with the HAWK-I near-infrared imager.\n\nWe obtained a multi-filter observation in the z-band and in the near-infrared YJHK bands.\nA preliminary analysis reveals no new sources consistent with the EP/FXT position (Mao et al., GCN 45543), down to the following 3-sigma limiting magnitudes (calibrated against Pan-STARRS and 2MASS for the optical and near-infrared bands, respectively):\n\n| Band | Mid time (UT) | T-T0 (hr) | Exposure time (min) | Instrument  | Magnitude (AB) |\n| - | -------------- | ------ | -- | ---------- | ------ |\n| z | 2026 Sep 10.21 | 17.65  | 20 | VLT/FORS2  | > 24.3 |\n| Y | 2026 Sep 10.19 | 17.35  | 10 | VLT/HAWK-I | > 23.9 |\n| J | 2026 Sep 10.20 | 17.56  |  8 | VLT/HAWK-I | > 23.6 |\n| H | 2026 Sep 10.21 | 17.76  |  8 | VLT/HAWK-I | > 23.1 |\n\nThe K-band integration was curtailed, and analysis of the frames obtained is ongoing.\n\nWe acknowledge the excellent support from the observing staff in Paranal.\n",
  "circularId": 45545,
  "eventId": "GRB 260909A",
  "submittedHow": "web",
  "bibcode": "2026GCN.45545....1S",
  "createdOn": 1789028623192,
  "eventType": [
    "GRB",
    "Optical Transient"
  ],
  "format": "text/markdown",
  "submitter": "Andrea Saccardi at CEA/Irfu <andrea.saccardi@cea.fr>",
  "subject": "GRB 260909A: VLT optical and near-infrared upper limits"
}