{
  "body": "N.P.M. Kuin (UCL-MSSL) and B. Cenko (NASA/GSFC) report on behalf of the\nSwift/UVOT team:\n\nThe Swift/UVOT began observations of the field of GRB 251129A  16.8 ks\nafter the SVOM  trigger (Tan et al., GCN Circ. 42877). GRB251129A was\nalso  detected\nby the EP (Wu et al, GCN Circ. 16828).\nThe optical afterglow consistent with the  SVOM/COLIBRI position (Angulo et\nal. GCN Circ. 42880; Watson, GCN Circ. 42883)  is detected in the initial\nUVOT exposures.\n\nPreliminary 3-sigma upper limits using the UVOT photometric system  (Breeveld\net al. 2011, AIP Conf. Proc. 1358, 373) are::\n\nFilter   T_start(s)  T_stop(s)  Exp(s)     Mag\n\nwhite    16828         17147     315    19.63 +/- 0.07\nwhite    27564        28089     502    19.69 +/- 0.12\nwhite   111007       117142    1044    20.22 +/- 0.12\nwhite   227072       234439    2745    20.92 +/- 0.17\nu        16503                   16823           315          20.06  +/-\n0.30\n\nThe magnitudes in the table are not corrected for the Galactic extinction due\nto the reddening of E(B-V) = 0.025 in the direction of the burst (Schlegel\net al. 1998).\n",
  "subject": "GRB251129A/EP251129a: Swift UVOT detection",
  "circularId": 42959,
  "submitter": "Paul Kuin at MSSL <npkuin@gmail.com>",
  "bibcode": "2025GCN.42959....1K",
  "createdOn": 1764700274496,
  "eventId": "GRB 251129A",
  "submittedHow": "email"
}