[vsnet-grb-info 14804] GRB 140419A: Swift detection of a burst with optical afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16118
SUBJECT: GRB 140419A: Swift detection of a burst with optical afterglow
DATE:    14/04/19 04:21:34 GMT
FROM:    Caryl Gronwall at PSU/Swift-UVOT  <caryl at astro.psu.edu>

F. E. Marshall (NASA/GSFC), J. R. Cummings (NASA/UMBC),
C. Gronwall (PSU), J. A. Kennea (PSU), A. Maselli (INAF-IASFPA),
T. Sakamoto (AGU), M. H. Siegel (PSU) and T. N. Ukwatta (MSU) report
on behalf of the Swift Team:

At 04:06:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140419A (trigger=596426).  Swift slewed immediately to the 
burst.  The BAT on-board calculated location is 
RA, Dec 126.999, +46.221 which is 
   RA(J2000) = 08h 28m 00s
   Dec(J2000) = +46d 13' 15"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 80 sec.  The peak count rate
was ~5611 counts/sec (15-350 keV), at ~52 sec after the trigger. 

The XRT began observing the field at 04:08:17.5 UT, 86.5 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 126.9909, 46.2416 which is equivalent to:
   RA(J2000)  = +08h 27m 57.82s
   Dec(J2000) = +46d 14' 29.8"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 76 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 5.09e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 96 seconds after the BAT trigger. A bright
uncatalogued source is  identified in the 2.7'x2.7' sub-image near the
position of the XRT afterglow. However, a more precise position is
unavailable at this time. The approximate  magnitude in the White
filter is 16.1.  No correction has been made  for the expected
extinction corresponding to E(B-V) of 0.03. 

Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)