Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 9210

Subject
GRB090423 - Swift/UVOT upper limits.
Date
2009-04-23T17:06:23Z (15 years ago)
From
Massimiliano de Pasquale at MSSL-UCL <mdp@mssl.ucl.ac.uk>
M. De Pasquale (MSSL/UCL) and H. Krimm (GSFC/GWU) report on
behalf of the Swift UVOT team:

The Swift/UVOT took the first settled exposure of GRB 090423 starting 
77 s after the BAT trigger (Krimm, et al., 2009, GCN Circ. 9198) in the 
white filter. We do not find any new source, at the enhanced position of 
the XRT afterglow (Evans, et al. 2009, GCN Circ. 9205) nor at the
position of the K band candidate found by UKIRT (Tanvir,
et al. 2009, GCN Circ. 9206). No source is detected even when all
the images of all filters are summed. The 3-sigma upper limits for
detecting a source in the white and u band first exposures, and
subsequent co-added images in all filters are:

Filter           T_start   T_stop   Exp(s)      Mag
----------------------------------------------------------
white               77      227     147         >20.7
u                   290     540     246         >20.0

v                  619      6162    413         >19.6
b                  545      5497    413         >20.2
u                  290      5342    462         >20.4
uvw1               668      6503    344         >20.1
uvm2               644      6367    413         >20.1
uvw2               594      5958    412         >20.5
white               77      5752    560         >21.3
---------------------------------------------------------

The quoted upper limits have not been corrected for the expected
modest Galactic extinction along the line of sight corresponding to a
reddening of E_{B-V} = 0.03 mag (Schlegel, et al., 1998, ApJS, 500,
525).  All photometry is on the UVOT photometry system described in
Poole et al. (2008, MNRAS, 383, 627).
Looking for U.S. government information and services? Visit USA.gov