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GCN Circular 6302

GRB 070419: Swift detection of a burst
2007-04-19T10:30:53Z (17 years ago)
David Palmer at LANL <>
M. Stamatikos (NASA/ORAU), D. N. Burrows (PSU), S. Campana (INAF-OAB),
G. Cusumano (INAF-IASFPA), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
C. Guidorzi (Univ Bicocca&INAF-OAB), V. La Parola (INAF-IASFPA),
W. B. Landsman (NASA/GSFC), V. Mangano (INAF-IASFPA),
C. B. Markwardt (GSFC/UMD), P. T. O'Brien (U Leicester),
D. M. Palmer (LANL), A. M. Parsons (GSFC),
P. Romano (Univ. Bicocca & INAF-OAB), B. Sbarufatti (INAF-IASFPA),
G. Stratta (ASDC), S. D. Vergani (DIAS-DCU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:

At 09:59:26 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070419 (trigger=276205).  Swift slewed immediately to 
the burst.  The BAT on-board calculated location is 
RA, Dec 182.714, +39.908 which is 
   RA(J2000) = 12h 10m 51s
   Dec(J2000) = +39d 54' 30"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve suggests emission from
T-10 to T+20 with a peak count rate of ~500 counts/sec (15-350 keV), 
at ~4 sec after the trigger.  However, as for most image triggers, 
the TDRSS light curve data is noisy and we will require the Malindi 
pass data for a more definitive analysis. 

The XRT began observing the field at 10:01:18 UT, 113 seconds after
the BAT trigger. XRT found a bright, fading and uncatalogued X-ray
source. The on ground calculated position is RA, Dec 182.7462,
+39.9245 which is   
  RA(J2000) = 12h 10m 59.1s   
  Dec(J2000) =39d 55' 28.2" 
with an uncertainty of 7.0 arcseconds (radius, 90%
containment). The given uncertainty takes into account the presence
of a nearby CCD bad column.   This location is 110 arcseconds from
the BAT on-board position, within the BAT error circle. The initial
flux in the 2.5s image was 3.7e-09 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 400 seconds with the V filter
starting 115 seconds after the BAT trigger. No afterglow candidate
has been found in the initial data products. The 2.7'x2.7' sub-image
covers 100% of the XRT error circle. The typical 3-sigma upper limit
has been about 18.5 mag. The 8'x8' region for the list of sources
generated on-board covers 100% of the XRT error circle. The list of
sources is typically complete to about 18.0 mag. No correction has been made
for the expected extinction of about 0.1 magnitudes. We note there is
a 7th magnitude star 3 arcminutes from the XRT position.
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