XRF 090702

A. Meshcheryakov (IKI), I. Khamitov (TUG), R. Burenin, M. Pavlinsky,
R. Sunyaev (IKI), Z. Eker (TUG), U. Kiziloglu (METU),  
E. Gogus (Sabanci Uni.), I. Bikmaev, N. Sakhibullin (KSU/AST)

report:

We observed the field of XRF 090702 detected with IBIS/INTEGRAL (Paizis
et al., GC N 9603;) with Russian-Turkish 1.5-m telescope (RTT150,
Bakirlitepe, TUBITAK National Observatory, Turkey), starting at 02 Jul,
18:54 UT, i.e. 8.2h  after the burst.

We made 2x600s exposures in SDSS r filter. In the combined image we do
not detect any sources inside the XRT/SWIFT error circle (Sbarufatti &
Mangano, GCN 9604
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 ). Using SDSS catalog for photometric calibration, we
estimate 3-sigma upper limit for any optical counterpart as  m_r > 22.4.

Sbarufatti B., Mangano V. (INAF-IASFPA) report on behalf of the Swift  
Team:

We have analyzed the Swift-XRT data of XRF 090702 (Paizis, et al., GCN  
Circ. 9603
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 ) comprising 6 ks in Photon Counting (PC) mode from T+16.5  
ks to T+25.4 ks.

The best position for the X-ray afterglow is the XRT UVOT-enhanced  
position:
RA, Dec = 175.89704, +11.50161 which is equivalent to:

RA (J2000):	11h 43m 35.29s
Dec (J2000):   +11d 30' 05.8"

with an uncertainty of 5.0 arcsec (radius, 90% confidence).

The light-curve consists of two data points at the level of some 1E-3  
counts/s, and shows evidence of a fading behaviour. A power-law  
extrapolation of the available data indicates a count-rate of 9.4E-5  
counts/s at T+48 h.

The average spectrum was fitted using Cash statistics with an absorbed  
power-law model. The absorbing column NH was fixed at the Galactic  
value of 3.5E20 cm^-2, the photon index is 1.9+/-0.4. The observed  
(unabsorbed) flux is 2.8(3.0)E-13 ergs cm^-2 s^-1. The C-statistic is  
29.3 with 32 bins. The count-rate to flux conversion factor is 4.4E-11.
All quoted errors are at 90% confidence level.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020106

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

P. D'Avanzo (Univ. Bicocca/INAF-OAB), S. Campana, S. Covino (INAF-OAB), 
E. Bozzo (ISDC) and L. Stella (INAF-OAR) report, on behalf of a larger 
collaboration:

We observed the field of XRF 090702 (Paizis et al., GCN 9603
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 ) with the 
ESO-VLT equipped with the FORS2 camera in imaging mode. In a first 
series of R-band images (6 minutes of total exposure time) carried out 
on Jul 2.9965, we do not see any optical counterpart inside the XRT 
error circle (Sbarufatti & Mangano, GCN 9604
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 ) down to a limiting 
magnitude of R > 24.2 (3sigma limit, calibrated against USNOB1 catalogue).

We note that the GRB position is about 10 deg from the Virgo Cluster.

We aknowledge the Paranal staff for their support, in particular C. 
Ledoux and K. O'Brien.

B. Sbarufatti, V. Mangano (INAF-IASFPA), report on behalf of the Swift- 
XRT team:

Swift began observation of the XRF detected by INTEGRAL  (Paizis, et  
al., GCN Circ. 9603
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 ) on 2009 July 2 at 14:15 UT, 3.5 hours after the  
trigger. In the XRT field of view we detect a single faint,  
uncatalogued source inside the IBIS/ISGRI error circle with a 5.5  
sigma significance. The XRT position obtained using a 6ks Photon  
Counting mode exposure is RA, Dec =
175.89800, 11.50219 which is equivalent to:

RA (J2000):  11 43 35.5
Dec (J2000): +11 30 07.9

with an uncertainty of 4.9 arcsec (radius, 90% confidence). This is  
0.6 arcmin away from the INTEGRAL IBIS/ISGRI position. The count-rate  
is (6.8+/-1.2)E-3 counts/s, for a total of 40 observed photons from  
the source. With the current amount of data we are unable to see if  
the source is fading.

This is an official product of the Swift XRT team.

A. Paizis (IASF-Milano), D.Gotz (CEA-Saclay), S.Mereghetti, (IASF- 
Milano), Wakiko Ishibashi, C. Ferrigno, M. Beck (ISDC, Versoix), and  
J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team  
report:
A long gamma ray burst with a soft spectrum, and without any  
detectable signal above 40 keV has been detected by IBAS in the IBIS/ 
ISGRI data at 10:40:37 U.T. on July 2nd. Its duration is about 10 s  
and its refined coordinates (J2000) are:
R.A.:      175.888 [degrees]
DEC.:    +11.501 [degrees]

with an uncertainty of 2.5 arcmin (90% c.l.).

A preliminary analysis gives a peak flux in the 20-200 keV range of   
about 0.15 ph/cmsq/s (1 s integration time) and a fluence over the same
energy range of about  1.5e-7 erg/cmsq.

A plot of the light curve will be posted at

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

This message can be cited.