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 10625

Subject
GRB 100418A: Swift/UVOT Observations
Date
2010-04-19T21:54:40Z (14 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@astro.psu.edu>
M. H. Siegel (PSU) and F. Marshall (NASA/GSFC) report on behalf
of the Swift/UVOT team.

The Swift/UVOT began settled observations of the field of GRB
100418A 87s after the BAT trigger (Marshall et al., GCN Circ. 10612).
Data summed from the first and second orbits reveals the source
reported by Marshall et al.  The source shows no fading between
the first and second orbits within the photometric uncertainties.
The photometry is consistent with a constant source with a white
magnitude of 20.48+-0.13.  This likely represents the GRB host
galaxy reported by Malesani (GCN Circ. 10621) and not the
afterglow reported by Filgas et al. (GCN Circ. 10617), Updike
et al. (GCN Circ. 10619) and Antonelli et al. (GCN Circ. 10620).
The UVOT position of the source is:

     RA(J2000.0) =  17:05:26.96  =  256.36278 (deg)
    Dec(J2000.0) = +11:27:41.9   =  +11.46167 (deg)

with a 90% confidence interval of 0."67.

The 3-sigma upper limits for the finding chart (fc) and
summed exposures from the first and second orbits are reported
below:

FILTER     T_start(s)  T_stop    Exposure     Mag/3UL
========================================================
white fc      87        237        147        20.62+-0.29
white         89       1548        390        20.58+-0.20
white       6143       6343        196        20.32+-0.20
v            628       6754        491        >19.90
b            554       6138        294        20.61+-.44
u            299       7348        697        20.47+-0.41
uvw1         678       7164        491        20.47+-0.42
uvm2         653       6959        491        20.09+-0.32
uvw2         604       6548        308        20.73+-0.54
=======================================================

The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.07 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric
system described in Poole et al. (2008, MNRAS, 383, 627).
Looking for U.S. government information and services? Visit USA.gov