RA = 274.4675 (18h 17m 52.20s),
Dec = -16.3589 (-16d 21' 31.9'') (J2000),
with a 90% confidence level error of 2.2 arcsec, consistent with the position measured by INTEGRAL/JEM-X (ATel #3947)(We have used the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue, see http://www.swift.ac.uk/user_objects and Evans et al. 2009, MNRAS, 397, 1177).
The two XRT spectra can be well fitted (reduced chi^2=0.72 for 47 dof and reduced chi^2=0.98 for 49 dof ) with an absorbed power-law model. The spectral parameters we derived in the 1-10 keV energy band are (model and flux uncertainties are 90% c. l.): In 2012-02-29, N_H = 11.0+/-2.7 e22 atoms/cm2 and photon index = 0.4+/-0.4. The 1-10 keV unabsorbed flux is 4.5+/-0.5 e-10 erg/cm2/s. In 2012-03-01, N_H = 15.1+/-3.6 e22 atoms/cm2 and photon index = 0.7+/-0.4. The 1-10 keV unabsorbed flux is 4.2+/-0.8 e-10 erg/cm2/s.
We derive from Swift/XRT a flux, between 3-10 keV, of 21.5+/-1.8 mCrab on 2012-02-29 and 22.0+/-2.2 mCrab on 2012-03-01, consistent with what was derived from JEM-X observation (ATel #3947).This may mean that IGR J18179-1621 now is still in a relatively bright phase.
No significant variation of the source spectral parameters are revealed in the XRT data.
|Publication date||2 Mar 2012|
|Publication status||Published - 2 Mar 2012|
|Series||The Astronomer's telegram|
- Black hole
- Neutron star
- Gamma ray