  We have observed the black hole candidate 1E 1740.7 - 2942, the brightest
persistent hard X-ray source within a few degrees of the Galactic centre, for
10 ksec with Chandra (ACIS-I) on August 2000. Attempting to compensate for
pile-up effects we found the spectra were well-fit by an absorbed power law,
with photon indices Gamma = 1.54 ^{+0.42}_{-0.37} (readout streak) and Gamma =
1.42^{+0.14}_{-0.14} (annulus), consistent with a black hole low/hard state. We
have analysed a public observation performed by Chandra which utilised short
frames in order to avoid severe pile-up effects: subtracting the core point
spread function from the whole image, we did not find evidence for any
elongated feature perpendicular to the radio jet axis, as reported in a recent
analysis of the same data. Moreover, comparing the radial profiles with those
of an unscattered X-ray point source, we found indication of an extended,
previously undetected, X-ray scattering halo. The measured halo fractional
intensity at 3 keV is between 30 and 40 percent within 40 arcsec but drops
below detectable levels at 5 keV. Finally, by placing a limit on the X-ray flux
from the radio emitting lobe which has been identified as the hot spot at the
end of the northern jet of 1E 1740.7 - 2942, we are able to constrain the
magnetic energy density in that region.
