XMM-Newton Science Analysis System


oal (oal-3.139) [xmmsas_20230412_1735-21.0.0]

SAS_TIMECORR

The conversion of Spacecraft-Onboard-Time (OBT) to Mission-Elapsed-Time (MET) tags can use either standard Time Correlation (TCS) data produced in real-time or Reconstructed Time Correlation data (TCX) produced through a reprocessing process designed to eliminate anomalies present in real-time data, stemming from timing issues in the XMM Ground Segment.

The environment variable allows the user to control this in the following manner:

value of SAS_TIMECORR	meaning
TCS	consider TCS data only; raise error condition if missing from ODF
TCS:TCX	first consider TCS data; if missing but TCX is present read TCX data; raise error condition otherwise, i.e. if both are missing
TCX:TCS	first consider TCX data; if missing but TCS is present read TCS data; raise error condition otherwise, i.e. if both are missing
TCX	consider TCS data only; raise error condition if missing from ODF

If the variable is not set the default behavior is identical to the setting SAS_TIMECORR=TCX:TCS.