Swift UVOT Detection of GRB 050318

M. Still, P.~W.~A. Roming, K.~O. Mason, A. Blustin, P. Boyd, A. Breeveld, P. Brown, M. De Pasquale, C. Gronwall, S.~T. Holland, S. Hunsberger, M. Ivanushkina, C. James, W. Landsman, K. McGowan, A. Morgan, T. Poole, S. Rosen, P. Schady, B. ZhangH. Krimm, T. Sakamoto, P. Giommi, M.~R. Goad, V. Mangano, K. Page, M. Perri, D.~N. Burrows, N. Gehrels, J. Nousek

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26 Citations (SciVal)


We present observations of GRB 050318 by the Ultraviolet/Optical Telescope (UVOT) on board the Swift observatory. The data are the first detections of a gamma-ray burst (GRB) afterglow decay by the UVOT instrument, launched specifically to open a new window on these transient sources. We showcase UVOT's ability to provide multicolor photometry and the advantages of combining UVOT data with simultaneous and contemporaneous observations from the high-energy detectors on the Swift spacecraft. Multiple filters covering 1800-6000 Å reveal a red source with a spectral slope steeper than the simultaneous X-ray continuum. Spectral fits indicate that the UVOT colors are consistent with dust extinction by systems at z = 1.2037 and 1.4436, redshifts where absorption systems have been preidentified. However, the data can be most easily reproduced with models containing a foreground system of neutral gas redshifted by z = 2.8 ± 0.3. For both of the above scenarios, spectral and decay slopes are, for the most part, consistent with fireball expansion into a uniform medium, provided a cooling break occurs between the energy ranges of the UVOT and Swift's X-ray instrumentation.
Original languageEnglish
Pages (from-to)1187-1191
Number of pages5
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 20 Dec 2005


  • Astrometry, Galaxies: Distances and Redshifts, Gamma Rays: Bursts, Shock Waves, X-rays: individual (GRB 050318), Astrophysics


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