{
  "bibcode": "2014GCN.17254....1S",
  "body": "L. P. Singer (NASA/GSFC), S. B. Cenko (NASA/GSFC), and M. M. Kasliwal\n(Carnegie Observatories/Princeton) report on behalf of the intermediate\nPalomar Transient Factory (iPTF) collaboration:\n\nFermi GBM detected GRB 141230A (Fermi trigger 441602665 / bn141230142) at\n2014-12-30 03:24:22.64. We searched for optical counterparts using the\nPalomar 48-inch Oschin telescope (P48), imaging 20 fields spanning an area\nof 147 deg2, covering about half of the 1-sigma statistical+systematic\nregion of the final Fermi GBM localization and part of the 2-sigma region.\nBased on the GBM localization, we estimate a 43% prior probability that\nthese fields contain the true location of the source.\n\nSifting through candidate variable sources using image subtraction and\nstandard iPTF vetting procedures, we detect the optical transient\niPTF14jko, at the coordinates:\n  RA(J2000)  =  4h 08m 41.48s (62.172836 deg)\n  Dec(J2000) = -6d 40' 36.0\"  (-6.676663 deg)\nNo source is detectable at this location in SDSS images. The last iPTF\nsurvey visit was on September 16. We report the following P48 photometry:\n  -104.7 day:   R > 20.12\n  +54.80 min:   R = 19.91 +/- 0.11\n  +129.9 min:   R = 19.75 +/- 0.14\nThe source does not appear to be fading at this time. Times are relative\nto the GBM trigger. Magnitudes are in the Mould R filter and in the AB\nsystem, calibrated with respect to point sources in SDSS as described in\nOfek et al. (2012, http://dx.doi.org/10.1086/664065).\n\nWe also detect the optical transient iPTF14jkn, at the coordinates:\n  RA(J2000)  =  3h 55m 02.59s (58.760779 deg)\n  Dec(J2000) = -6d 44' 04.2\"  (-6.734503 deg)\nWe note that this position is near the bright (r = 13.59 mag) star,\nSDSS J035501.84-064404.9. We report our P48 photometry:\n  -104.7 day:   R > 20.34\n  +98.02 min:   R = 19.60 +/- 0.10\nPoor seeing conditions may call into question the veracity of this optical\ntransient and the accuracy of its photometry.\n\nWe have submitted a Swift TOO for iPTF14jko. Further observations are\nencouraged to determine the nature of the source.\n\nThe diagram http://www.its.caltech.edu/~lsinger/iptf/Fermi441602665.pdf\nshows our P48 fields and the location of the optical transient candidates\nin relation to the Fermi GBM 1- and 2-sigma statistical+systematic\ncontours.",
  "circularId": 17254,
  "createdOn": 1419928083000,
  "email": "lsinger@caltech.edu",
  "subject": "GRB 141230A: iPTF Optical Observations and Candidate Afterglow iPTF14jko",
  "submitter": "Leo Singer at CIT/PTF  <lsinger@caltech.edu>",
  "eventId": "GRB 141230A"
}