How far can I trust the results of my timing analysis?
Nominally, the X-ray instruments on board XMM-Newton ensure
a time resolution ranging from about one hundredth to tens of
milliseconds (cf. the XMM-Newton
instrument overview). However, some effects can affect
and partly degrade the nominal accuracy. The main ones
can be summarized as follows:
- on board time wrap-around events: please refer
to the following
- jumps in the ground station clocks: these events
may sporadically occur during the handover between two
antennas tracking the satellite. They imply a time shift of the order of tenths of seconds each. In order to correct for them, a new ODF constituent, the Reconstructed Time Correlation file, is being added to all ODFs. "Reconstructed Time Correlation" is time correlation rebuilt from raw telemetry and corrected for symmetrical ground station clock jumps (i.e. in the case where one ground station experiences a clock jump that disappears with the handover to the next ground station).
The SAS is being updated to use the new data and is in the process of scientific validation.
Pages maintained by SAS librarian.
Any question about SAS should be addressed to the
XMM-Newton help desk.
June 18, 2009