{
  "createdOn": 1756054229966,
  "format": "text/plain",
  "bibcode": "2025GCN.41529....1O",
  "circularId": 41529,
  "submitter": "d.s.oneill@bham.ac.uk",
  "body": "D. O'Neill, A. Kumar, G. Ramsay, B. P. Gompertz, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares\n\nWe report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to the EP/WXT alerts 01709200706 and 01709200707. \nObservation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). \n\nTargeted observations of EP-WXT 01709200706 were taken at 2025-08-24 12:46:36 UT (+3.13h post trigger) and 2025-24-08 14:10:18 UT (+4.53h post trigger). We detect a single new source in difference imaging, consistent with the flaring star UCAC4 277-216984, as identified by Li et al. (GCN 41524). The star is saturated in our unsubtracted frames, meaning we cannot robustly determine the magnitude other than place lower limits of L>11.94 AB mag and L>12.11 AB mag at +3.13h and +4.53h post trigger, respectively.\n\nTargeted observations of EP-WXT 01709200707 were taken at 2025-08-24 12:54:10 UT (+0.22h post trigger) and 2025-08-24 14:02:40 UT (+1.36h post trigger). We identify a new source in differencing imaging consistent with UCAC4 268-197742  identified by Li et al. (GCN 41526). The star reaches a peak magnitude in our unsubtracted frames of L=14.31±0.01  and L=15.16±0.01 AB mag at +0.22h and +1.36h post trigger, respectively.\nImages were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations.\n\nGOTO (https://goto-observatory.org) is a network of telescopes that is\nprincipally funded by the STFC and operated at the Roque de los Muchachos\nObservatory on La Palma, Spain, and Siding Spring Observatory in NSW,\nAustralia, on behalf of a consortium including the University of Warwick,\nMonash University, Armagh Observatory & Planetarium, the University of\nLeicester, the University of Sheffield, the National Astronomical Research\nInstitute of Thailand (NARIT), the University of Turku, the University of\nPortsmouth, the University of Manchester and the Instituto de Astrofisica\nde Canarias (IAC).\n",
  "subject": "EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars",
  "submittedHow": "web"
}