[vsnet-grb-info 15998] Swift detection of 4U 1700+24 (= V* V934 Her)

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17280
SUBJECT: Swift detection of 4U 1700+24 (= V* V934 Her)
DATE:    15/01/04 16:08:43 GMT
FROM:    David Burrows at PSU/Swift  <burrows at astro.psu.edu>

D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC),
M.E. Gropp (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 15:39:06 UT, the Swift Burst Alert Telescope (BAT) triggered and
located 4U 1700+24 (= V934 Her) (trigger=623434).  Swift slewed 
immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 256.627, +23.962 which is 
   RA(J2000) = 17h 06m 30s
   Dec(J2000) = +23d 57' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). As is usual with an image trigger, the available
BAT light curve shows no significant structure. 

The XRT began observing the field at 15:45:46.6 UT, 399.7 seconds after
the BAT trigger. XRT found a bright X-ray source located at RA, Dec
256.6423, 23.9712 which is equivalent to:
   RA(J2000)  = +17h 06m 34.15s
   Dec(J2000) = +23d 58' 16.3"
with an uncertainty of 5.2 arcseconds (radius, 90% containment). This
location is 60 arcseconds from the BAT onboard position, within the BAT
error circle. This position is 5.5 arcseconds from a known X-ray
source: 1SXPS J170634.5+235816, which is coincident with V* V934 Her. 
This source is in the Swift XRT 1SXPS catalogue 
with a mean 0.3-10 keV count-rate of 0.3810 +/- 0.0067 ct/sec; 
see http://www.swift.ac.uk/1SXPS/1SXPSJ170634.5%2B235816 for
details of these previous observations. 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 1.90e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 411 seconds after the BAT trigger. The 2.7'x2.7' sub-image only
shows the bright (V=7.6) known source V* V934 Her. 

This symbiotic star has been seen by Swift multiple times in the past 
few months (e.g. Kennea et al., GCN 17173; Krimm et al. ATel 6482) in
an escalating series of peaks.  The BAT lightcurve can be seen at

http://swift.gsfc.nasa.gov/results/transients/weak/4U1700p24/