In the telemetry, all events are recorded with energy, segment and time information. In the software, when a front and rear segment event are recorded in the same detector (sub-collimator) within a narrow time window, those front-segment events are flagged as being coincident (probably non-solar).
The following types of front-segment data can be obtained:
anticoincident - front segment events are only included if there is NO coincident rear event
total - all front-segment events independent of any rear-segment events (sum of anticoincident and coincident events)
If you want to obtain coincidence spectrum alone, you must use the command line to take the difference of the total and anticoincidence spectra.
The image and spectrum objects handle anticoincidence slightly differently.
SPECTRUM OBJECT
There are two control parameters that dictate what front-segment spectrum is returned by the object:
COINCIDENCE_FLAG - controls what is stored internally
0 - (default) only the anticoincident events are stored
1 - the anticoincident and coincident events are stored (separately)
SUM_COINCIDENCE - controls what is returned and displayed
0 - (default) only anticoincident events
1 - the sum of the anticoincident and coincident events (this forces COINCIDENCE_FLAG to be 1 also)
The default is to store and return the anticoincident events. If you set COINCIDENCE_FLAG=1 (either explicitly or by setting SUM_COINCIDENCE=1), then the data must be reaccumulated, but once both anticoincident and coincident data have been stored, changing these parameters does not require reprocessing.
IMAGE OBJECT
In the image object, COINCIDENCE_FLAG has no effect. SUM_COINCIDENCE controls whether to use the anticoincidence events alone (SUM_COINCIDENCE=0, the default), or the sum of the anticoincident and coincident events (SUM_COINCIDENCE=1). If you change the value of SUM_COINCIDENCE, the data must be reaccumulated.
For rear-segment spectra, there is one control parameter (we recommend not changing this from the default of 1):
REAR_NO_ANTI
0 - anticoincidence flag is used to remove counts from rear segments
1 - (default) do not remove counts from rear segments based on coincidence flag