{
  "bibcode": "2000GCN...712....1F",
  "body": "A. Fruchter (STScI), S. Thorsett (UCSB), R. Wijers (SUNY) report for the\nlarger HST GRB collaboration:\n\nPublic HST observations in the red (LP) STIS filter should shortly be\navailable of the host galaxy of GRB 990123.  We therefore report here\non the results of late-time imaging of the host by our group using the\nwide-band open (50CCD) filter.  The images described here can be found\nat http://www.stsci.edu/~fruchter/GRB , and will be submitted to a\njournal shortly.\n\nThe field of GRB 990123 was reobserved by HST with the STIS CCD in open\nfilter (50CCD) mode during two orbits on 7 February 2000, or 380 days\nafter the GRB.  The optical transient was no longer visible.   However\nwe have been able to use this image to further refine our earlier\nphotometry on the OT (Fruchter et al. 1999a,b).    We now find \na V magnitude for the OT of 25.4 +/- 0.1 on 8 February 1999 and\nV = 27.7 +/- 0.15  on 23 March 1999, implying that the late time\nlate-time light curve falls as t^{-1.7 +/- 0.1}.  This represents a\nbreak of about 0.65 from the power-law decay a couple of days after\noutburst, and thus is roughly consistent with the beaming model of\nMeszaros and Rees (1999).  However, this also agrees within the errors\nwith the power-law of the early time light curve reported by ROTSE, and\nthis may suggest a connection between the early and late-time\nemission.\n\nThe GRB is found to reside near the edge of the visible stellar field\nof the host, and is not superposed on a strong region of star-formation.\n\nReferences:\n\nAkerlof, C. et al, 1999, Nature, 398 400.\nFruchter, A. et al., 1999, Ap. J. (Letters), 519, L13.\nFruchter, A. et al., 1999, GCN 354.\nMeszaros, P. and Rees, M., 1998, MNRAS, 306L, 39.",
  "circularId": 712,
  "createdOn": 961210306000,
  "email": "fruchter@stsci.edu",
  "subject": "GRB 990123: Late-time HST/STIS 50CCD observations of the host",
  "submitter": "Andrew S. Fruchter at STScI  <fruchter@stsci.edu>",
  "eventId": "GRB 990123"
}