Events

A frame can enable checks for 3 types of events:

flare
super flare
transient

Any or all can be enabled via the check box. Parameters for
each are specified with the text boxes under rates and pixels.
These are described further below. Note that the pixels value
for super flare is the same as that for the flare event. Hence
it is grayed out and you can not change the value in that text
window. It will just be a copy of the flare value whenever a
frame is read in or a scan or write is performed. Also note
that a transient event can be either dark or bright (not both)
as selected by the option menu below the transient check box.

Event testing is enabled when the corresponding flag is set.
The s/w tests for flares by checking if the count level
exceeds the flare rate in least the specified number of
pixels (the rates and pixels boxes in the widget). The number
of pixels represents the number of "real" pixels in the CCD
in the case of binning or summing. Also, the count rate is
a count per second rate with the average amplifier bias
(dark count level) removed. Hence the parameters are
independent of exposure time and binning/summing mode. For
further details, read the TRACE control document available on
the TRACE Web page.

Super flare testing is similar to flare testing but uses a
different (generally higher) count rate and the same value for
the minimum pixel count.

Transient testing uses the same concept of minimum pixel count
but tests for a relative increase (or decrease) specified by
the rate parameter. This must be in the range 101 to 255 and
represents the relative increase (or decrease) level times 100.
Hence 101 means that an increase of 1% is counted as significant
and 150 looks for 50% increases (or decreases). Transient testing
also works with the current and previous time averaged images
rather than just examined the current exposure. Hence, time
averaging must be enabled for the transient event to be tested.
To trigger a bright transient flag with a "rate" of 150 and a
pixel area of 50 means that at least 50 pixels in the current
time average must have an increase in brightness of 50% or more
from the previous time averaged image. Note that the number of
images that can be summed for a time average ranges from 1 to 16.

For further details and the algorithms actually used, read the
control document available on the Web pages.