{
  "bibcode": "2012GCN.13084....1F",
  "body": "W. Fong, E. Berger, N. Sanders (Harvard), K. Cooksey, A. Zangari (MIT) and\nN. Morrell (LCO) report:\n\n\"We observed the location of the short-duration GRB 120229A (GCN 12997)\nwith the Low Dispersion Survey Spectrograph 3 (LDSS3) mounted on the\nMagellan/Clay 6.5-meter telescope. We obtained 3x180-sec\nr-band observations on 2012 March 01.01 UT (9.6 hours post-burst) at\nhigh airmass in mediocre seeing conditions (1.3\"). To check for the\npresence of a fading optical source, we re-observed the field (6x180-sec)\non 2012 March 02.01 UT (33.6 hours post-burst and 24.0 hours after\nthe first observations) at similar airmass. Digital image subtraction\nof the two epochs using the ISIS software package reveals no\nresiduals within the BAT-refined position (GCN 12998). Therefore,\ncalculating the zeropoint from a standard star field at similar\nairmass based on several stars, we place a 3-sigma limit of r>22.4 mag on\nthe optical afterglow of GRB 120229A at 9.6 hours after the burst.\"",
  "circularId": 13084,
  "createdOn": 1332337279000,
  "email": "wfong@cfa.harvard.edu",
  "subject": "GRB 120229A: Magellan observations and limit on an optical afterglow",
  "submitter": "Wen-fai Fong at CFA  <wfong@cfa.harvard.edu>",
  "eventId": "GRB 120229A"
}