{
  "subject": "GRB 160623A: Swift/UVOT Upper Limits",
  "eventId": "GRB 160623A",
  "bibcode": "2016GCN.19568....1B",
  "createdOn": 1466796712000,
  "circularId": 19568,
  "submitter": "Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>",
  "email": "a.breeveld@ucl.ac.uk",
  "body": "Alice Breeveld (UCL-MSSL) and A. Maselli (INAF-IASFPA)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 160623A\n40254 s after the LAT trigger (Vianello et al., GCN Circ. 19553).\nNo optical afterglow consistent with the XRT position (Mingo et al. GCN \nCirc. 19558) or the Mondy and RATIR position (Pozanenko et al. GCN Circ. \n19561; Butler et al. GCN Circ. 19567) is detected in the initial UVOT \nexposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial \nexposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nv                40657        51652         2859         >21.1\nu                40254        51253         2008         >21.5\n\nThe magnitudes in the table are not corrected for the Galactic \nextinction due to the reddening of E(B-V) = 1.35 in the direction of the \nburst (Schlegel et al. 1998)."
}