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TITLE:   GCN CIRCULAR
NUMBER:  6823
SUBJECT: GRB 070925: a long GRB detected by INTEGRAL
DATE:    07/09/25 17:26:59 GMT
FROM:    Sandro Mereghetti at IASF/CNR  <sandro@iasf-milano.inaf.it>

S.Mereghetti, A.Paizis (IASF-Milano), D.Gotz (CEA-Saclay), D.Petry, 
V.Beckmann, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) 
on behalf of the IBAS Localization Team report:

A  GRB lasting about 30 s has been detected by IBAS in IBIS/ISGRI 
data at 15:52:32 UT of September 25.
The coordinates (J2000)  are:

RA:  253.218 [degrees] 
DEC: -22.0355 [degrees]

with an uncertainty of 2 arcmin (90% c.l.).

The light curve is affected by gaps due to telemetry saturation. The peak 
flux in the 20-200 keV range is 2 ph/cmq/s (1-s integration time) and the 
fluence over the same energy range is larger than 2x10e-6 erg/cmq.

A plot of the light curve will be posted at

http://ibas.iasf-milano.inaf.it/IBAS_Results.html

This message can be cited.

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TITLE:   GCN CIRCULAR
NUMBER:  6826
SUBJECT: GRB070925: Swift-XRT Position
DATE:    07/09/26 15:00:58 GMT
FROM:    Loredana Vetere at PSU  <vetere@astro.psu.edu>

L. Vetere, J. L. Racusin (PSU) report on behalf of the Swift-XRT team:

We have analysed 2.5 ks of Swift XRT data for GRB 070925 (Mereghetti et al.,
GCN 6823) beginning 12 ks after the IBAS trigger. An uncatalogued X-ray source
is clearly detected at RA, Dec= 253.21700, -22.02856 degrees, which is
equivalent to:

RA (J2000) =  16h 52m 52.1s
Dec(J2000) = -22d 01' 41.0"

with an estimated uncertainty of 6.0 arcsec (radius, 90% containment
including boresight uncertainty). This is 8 arcsec from the IBAS
position (Mereghetti et al., GCN 6823) within its error circle. The
source has a count rate of 1.6e-2 +/- 0.3e-2 counts s-1. At present we
are unable to determine whether the source is fading, however
observations are ongoing.

This circular is an official product of the Swift-XRT team.

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TITLE:   GCN CIRCULAR
NUMBER:  6827
SUBJECT: GRB 070925: Gemini South Imaging
DATE:    07/09/26 20:32:08 GMT
FROM:    Hsiao-Wen Chen at U Chicago  <hchen@oddjob.uchicago.edu>

J.S. Bloom (UC Berkeley), D. A. Perley (UC Berkeley), H.-W. Chen (U 
Chicago), an d J.X. Prochaska (UCO/Lick) report on behalf of a larger 
collaboration:

"We observed the field of GRB 070925 (Mereghetti et al., GCN 6823) in
r-band with the Gemini South 8-m telescope for a total of 900 sec
starting at 2007-09-26 00:00:59 UT.  The stacked image has a mean seeing
of ~ 1.0 arcsec.  Within the XRT (Vetere et al. GCN 6826) there are two
apparent binary systems, both apparent in DSS imaging (mid-points
16:52:52.5, -22:01:41 and 16:52:52.1, -22:01:41). We detect no other
sources in the error circle to r~24.5.

This message may be cited. "

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TITLE:   GCN CIRCULAR
NUMBER:  6828
SUBJECT: GRB070925: Swift-XRT Afterglow confirmation
DATE:    07/09/27 16:48:43 GMT
FROM:    Loredana Vetere at PSU  <vetere@astro.psu.edu>

L. Vetere, C. Pagani (PSU) report on behalf of the Swift-XRT team:

Additional Swift-XRT observations have been performed of the possible
X-ray afterglow of GRB 070925 (Vetere et al., GCN 6826). The count rate
at T+72h is ~3e-3 counts/s. Between 1.3e4 and 1.4e5 seconds after the burst,
the source has faded following a power-law decay slope of alpha = 1.2 +/- 0.3,
confirming that it is, indeed, the afterglow.
If the burst keeps decaying at the current rate the predicted count rate at
T+96h is 5.6e-4 counts/s.

This circular is an official product of the Swift-XRT team.