XMM-Newton Science Analysis System
phasecalc (dscalc-2.6) [xmmsas_20060628_1801-7.0.0]
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Given an ephemeris and a list of event tables, phasecalc
calculates the phase of each event in each of the tables. The
calculated values are stored in a column named PHASE. If the
column exists it is overwritten.
relies on the event table having a TIME
column and the two attributes MJDREF and TIMEZERO.
- MJDREF is the Modified Julian Day from which times are
- TIMEZERO is the clock correction at the start of the
observation in seconds.
also uses the TIMESYS keyword to determine the
Time System (UTC, TT, TAI) used in event table. If the TIMESYS keyword is
not UTC, the Reference Epoch time of the ephemeris is converted to the
appropriate Time System. In the absence of this keyword TT (XMM Time)
The time of event n is then:
is the value stored in the TIME column.
An ephemeris is specified in terms of four quantities:
- reference epoch ; This is UTC.
- reference phase ;
- frequency in Hz;
- frequency time derivative in Hz/s.
The phase of event n is defined as:
XMM-Newton SOC/SSC -- 2006-06-28