{
  "bibcode": "2014GCN.16451....1D",
  "body": "V. D'Elia (ASDC), F. E. Marshall (NASA/GSFC), L. Izzo (URoma/ICRA) &  \nD. Malesani (DARK/NBI) report on behalf of the Swift team:\n\nFollowing the report of a potential optical afterglow iPTF14cyb  \n(Bhalerao et al., GCN Circ. 16442) to the Fermi/GBM-detected burst GRB  \n140623A (von Kienlin, GCN Circ. 16450), Swift began a follow-up  \nobservation of the iPTF field.\n\nWe have analyzed all the 3.0 ks of XRT data for GRB 140623A,  from  \n38.7 ks to 49.6 ks after the Fermi/GBM trigger. The data are entirely  \nin Photon Counting (PC) mode. An X-ray source is detected at a  \nposition consistent with the candidate optical afterglow (Bhalerao et  \nal., GCN Circ. 16442) within the Fermi/GBM error circle.\n\nUsing 1153 s of PC mode data and 1 UVOT images, we find an enhanced  \nXRT position (using the XRT-UVOT alignment and matching UVOT field  \nsources to the USNO-B1 catalogue): RA, Dec = 225.47927, +81.19049  \nwhich is equivalent to:\n\nRA (J2000): 15h 01m 55.02s\nDec(J2000): +81d 11' 25.7\"\n\nwith an uncertainty of 5.8 arcsec (radius, 90% confidence). This  \nposition is 5.0 arcsec from the the optical counterpart iPTF14cyb, and  \nconsistent with it. We cannot determine at the present time whether  \nthe source is fading.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00020388.\n\nThe Swift/UVOT began settled observations of the field of GRB 140423A  \n38708 s after the GBM trigger. No optical afterglow consistent with  \nthe optical position (Bhalerao et al. GCN Circ. 16442) is detected in  \nthe initial UVOT exposures. Preliminary 3-sigma upper limits using the  \nUVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358,  \n373) are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nu                38708        44173          925         >22.0\nwhite            38926        44863          851         >21.9\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.037 in the direction of the burst\n(Schlegel et al. 1998).\n\nThis circular is an official product of the Swift team.",
  "circularId": 16451,
  "createdOn": 1403623275000,
  "email": "delia@asdc.asi.it",
  "subject": "GRB 140623A: Swift-XRT and UVOT observations",
  "submitter": "Valerio D'Elia at ASDC  <delia@asdc.asi.it>",
  "eventId": "GRB 140623A"
}