{
  "bibcode": "2014GCN.16080....1F",
  "body": "W. Fong (Harvard), S. Ehlert (MIT), D. Osip (LCO/OCIW), B. Rackham\n(Arizona), M. McDonald (MIT), and E. Berger (Harvard) report:\n\n\"We observed the location of the short-duration GRB 140402A, detected by\nFermi/LAT (Bissaldi et al., GCN 16069), Fermi/GBM (Jenke et al., GCN 16070)\nand Swift/BAT (Cummings et al., GCN 16071) with the Inamori Magellan Areal\nCamera and Spectrograph (IMACS) mounted on the Magellan/Baade 6.5-m\ntelescope to cover the full refined BAT position (Cummings et al., GCN\n16073). We obtained 3x300-sec r-band observations on 2014 Apr 03.22 UT\n(1.21 days post-burst) in 0.7\" seeing at an airmass of 1.2. To check for\nthe presence of a fading optical source, we re-observed the field\n(3x300-sec) on 2014 Apr 04.35 UT, 2.33 days post-burst and 1.12 days after\nthe first set of observations. Digital image subtraction of the two epochs\nusing the ISIS software package reveals no residuals in or around the\nBAT-refined position. Therefore, calibrated to SDSS DR9 sources in the same\nfield, we place a 3-sigma limit of r>25.0 mag on the optical afterglow of\nGRB 140402A at 1.21 days after the burst.\"",
  "circularId": 16080,
  "createdOn": 1396632401000,
  "email": "wfong@cfa.harvard.edu",
  "subject": "GRB 140402A: Deep limit on the optical afterglow from Magellan observations",
  "submitter": "Wen-fai Fong at CFA  <wfong@cfa.harvard.edu>",
  "eventId": "GRB 140402A"
}