{
  "bibcode": "2013GCN.15637....1C",
  "body": "R. Chornock, W. Fong, and E. Berger (Harvard) report:\n\nWe observed the field of GRB 131229A (Page et al., GCN 15627) using LDSS3 on the \n6.5 m Magellan Clay telescope starting 21 minutes after the BAT trigger. Initial \nr' and i' images in 0.8\" seeing revealed no clear counterpart, consistent with \nthe upper limits reported by other groups (Perley, GCN 15628; Zheng et al., GCN \n15629; Perley et al., GCN 15630; Graham et al., GCN 15636; de Pasquale et al., \nGCN 15633). We then obtained a sequence of 7x180s z'-band images starting at \nt=+34 min after the trigger. The sources labeled A and B by Perley et al. (GCN \n15628) are visible outside of the enhanced XRT error circle (Evans et al., GCN \n15631). However, a stack of our images reveals no sources within the enhanced \nXRT error circle. We set a 3-sigma upper limit of z'>24.3 mag (AB) at a midpoint \nof t=+49 minutes.",
  "circularId": 15637,
  "createdOn": 1388386864000,
  "email": "rchornock@cfa.harvard.edu",
  "subject": "GRB 131229A: Magellan upper limit",
  "submitter": "Ryan Chornock at Harvard  <rchornock@cfa.harvard.edu>",
  "eventId": "GRB 131229A"
}