We report the first unambiguous detection of X-ray emission originating from Saturn with a Chandra observation , duration 65.5 ksec with ACIS-S3 .
Beyond the pure detection we analyze the spatial distribution of X-rays on the planetary surface , the light curve , and some spectral properties .
The detection is based on 162 cts extracted from the ACIS-S3 chip within the optical disk of Saturn .
We found no evidence for smaller or larger angular extent .
The expected background level is 56 cts , i.e. , the count rate is ( 1.6 \pm 0.2 ) \cdot 10 ^ { -3 } cts/s .
The extracted photons are rather concentrated towards the equator of the apparent disk , while both polar caps have a relative photon deficit .
The inclination angle of Saturn during the observation was \sim - 27 ^ { \circ } , so that the northern hemisphere was not visible during the complete observation .
In addition , it was occulted by the ring system .
We found a small but significant photon excess at one edge of the ring system .
The light curve shows a small dip twice at identical phases , but rotational modulation can not be claimed at a significant level .
Spectral modeling results in a number of statistically , but not necessarily physically , acceptable models .
The X-ray flux level we calculate from the best-fit spectral models is \sim 6.8 \cdot 10 ^ { -15 } \mbox { erg cm } ^ { -2 } \mbox { s } ^ { -1 } ( in the energy interval 0.1–2 keV ) , which corresponds to an X-ray luminosity of \sim 8.7 \cdot 10 ^ { 14 } \mbox { erg } \mbox { s } ^ { -1 } .
A combination of scatter processes of solar X-rays require a relatively high albedo favoring internal processes , but a definitive explanation remains an open issue .