Bug when TOTCTS keyword value different from the EVENTS keyword value
There is a bug in glvary whenever it internally filters out events. If the TOTCTS keyword and the EVENTS keyword have different values, then this bug has been triggered. There are two conditions under which this may occur:
- If using an efficiency file, efffile, and the time range of the efffile is shorter than the time range of the events. Events outside the time range will be filtered out and triggers this bug.
- When working with ACIS event files with a source that spans multiple CCDs. Since the GTIs are different for each CCD, and glvary only uses the first GTI, it may be that some events are filtered out when the GTI is applied; which would trigger this bug.
Unfortunately, the effects of the bug are unpredictable. There may be circumstances where a variable source does not look variable when this bug is triggered. Similarly, there may be cases were a non variable source appears variable. And there may be times when the results are not substantially affected by the presence of this bug.
The magnitude of the difference in keyword values does not matter. A difference of 1 is as suspicious as a difference of 10 or 100.