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XMM-Newton Science Analysis System

emframes (emframes-5.11) [xmmsas_20211130_0941-20.0.0]


emframes analyzes the frames (auxiliary) file, adding four columns (a quality flag, the dead time fraction, the time and the GATTI value), performing various checks and computing the specific (to the CCD node) Good Time Intervals. The flag value allows to identify why the frame was flagged (using binary coding). emframes does not normally modify the events file (except in the case of frame renumbering as explained below). Events belonging to frames flagged as bad are themselves flagged for rejection by CUT_GTI in emevents.
emframes may be applied as is to slew data.

emframes may renumber the frames in the case of long telemetry drops. Frame renumbering allows to compute the GATTI value correctly, and to flag the events with truncated energy (as REJECTED_BY_GATTI) in emevents. Those flagged events are the best way to detect proton flares. Frame renumbering requires altering the events file as well.

When it is launched on an auxiliary file (straight from the ODF), emframes needs to access the ODF directory where the data comes from. This should be specified through the SAS_ODF environment variable, or the generic odf parameter on the command line. In that context, emframes also needs an events file (odfeventset parameter) to define the CCD/node and set the OAL state.
In that case emframes writes to the output frames file keywords filled using values taken from the summary file via OAL calls. It also copies the FILTER keyword to the events file (for the CAL) if the events file was modified (newevent=Y or frame renumbering). If the events file was not modified the FILTER keyword is not copied to avoid the overhead of rewriting the full file.

On the other hand, emframes launched on its own output does not need an ODF directory nor an events file. All functions described below may be called that way except FRAMES.

emframes calls (in order) the following subroutines, all of which can be individually switched off:

Recapitulation of flag definitions (flags below 64 are just warnings):

1 Extended frame integration time
2 Telemetry drop before this frame
4 Frame kept from a sequence of duplicated data with increasing IDs
8 No attitude available (Timing mode only)
16 Frame thought to contain good data, whose ID number was duplicated
64 Frame thought to contain bad data, whose ID number was duplicated
128 NPIXEL too small or NABOVE too large
256 Frame is not inside Good Time Interval from Housekeeping
512 FIFO overflow
1024 Number of events in the events file is not NVALID
2048 Time negative or aberrant leap in time tag
4096 Missing frame inserted after detection of telemetry drop
8192 First or last frame
16384 Time decreased unexpectedly

XMM-Newton SOC -- 2021-11-30