E. Sonbas (NASA/GSFC/Adiyaman Univ.), S. D. Barthelmy (GSFC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf
of the Swift Team:
At 09:44:45 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130615A (trigger=558271). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 274.846, -68.166 which is
RA(J2000) = 18h 19m 23s
Dec(J2000) = -68d 09' 57"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). As is typical for image triggers, there is nothing
obvious in the real-time TDRSS light curve.
The XRT began observing the field at 09:47:39.3 UT, 174.1 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 274.82944, -68.16032 which
is equivalent to:
RA(J2000) = 18h 19m 19.07s
Dec(J2000) = -68d 09' 37.2"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 30 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. We
cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (8.27 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 3
(+2.62/-2.27) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 2.11e-09 erg cm^-2 s^-1 (0.2-10
UVOT took a finding chart exposure of 250 seconds with the U filter starting
179 seconds after the BAT trigger. No credible 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 19.2 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 corresponding to E(B-V) of
Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com).
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.)