We report on X-ray observations of the the large-scale jets recently discovered in the radio and detected in X-rays from the black hole candidate X-ray transient and microquasar XTE J1550–564 .
On 11 March 2002 , X-ray emission was detected 23 \arcsec to the West of the black hole candidate and was extended along the jet axis with a full width at half maximum of 1.2 \arcsec and a full width at 10 % of maximum intensity of 5 \arcsec .
The morphology of the X-ray emission matched well to that of the radio emission at the same epoch .
The jet moved by 0.52 \arcsec \pm 0.13 \arcsec between 11 March and 19 June 2002 .
The apparent speed during that interval was 5.2 \pm 1.3 mas / day .
This is significantly less than the average apparent speed of 18.1 \pm 0.4 mas / day from 1998 to 2002 , assuming that the jet was ejected in September 1998 , and indicates that the jet has decelerated .
The X-ray spectrum is adequately described by a powerlaw with a photon index near 1.8 subject to interstellar absorption .
The unabsorbed X-ray flux was 3.4 \times 10 ^ { -13 } erg cm ^ { -2 } s ^ { -1 } in the 0.3-8 keV band in March 2002 , and decreased to 2.9 \times 10 ^ { -13 } erg cm ^ { -2 } s ^ { -1 } in June .
We also detect X-rays from the eastern jet in March 2002 and show that it has decelerated and dimmed since the previous detections in 2000 .