Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

GCN Circular 6383

GRB 070508: Swift detection of an intense burst with an optical counterpart
2007-05-08T04:47:27Z (17 years ago)
Scott Barthelmy at NASA/GSFC <>
D. Grupe (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU),
G. Cusumano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD),
F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL),
J. L. Racusin (PSU), M. Stamatikos (NASA/ORAU) and L. Vetere (PSU)
report on behalf of the Swift Team:

At 04:18:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070508 (trigger=278854).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 312.783, -78.368 which is 
   RA(J2000)  =  20h 51m 08s
   Dec(J2000) = -78d 22' 04"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a complex multi-peaked
structure with a duration of at least 40 sec.  The peak count rate
was ~45000 counts/sec (15-350 keV), at ~15 sec after the trigger. 

The XRT began observing the field at 04:19:33 UT, 76 seconds after the
BAT trigger. XRT found a bright, uncatalogued X-ray source
located at RA, Dec 312.7959, -78.3850 which is
RA(J2000)  =  20h 51m 11.0s
Dec(J2000) = -78d 23' 06.0"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). 
This location is 62 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 1.6e-09 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 85 seconds after the BAT trigger. There is a candidate
afterglow in the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	20:51:11.81 = 312.7992
  DEC(J2000) = -78:23:04.9  = -78.3847
with a 1-sigma error radius of about 0.5 arc sec. This position is 2.6 arc sec. 
from the center of the XRT error circle. The estimated magnitude is 19.4 with a
1-sigma error of about 0.5 mag. No correction has been made for the expected
reddening of E(B-V) of 0.14.
Looking for U.S. government information and services? Visit