...
- We will use the EVENT_CLASS column to designate the single event class to which are particular event belongs. In the case of Pass 5, the CTBCLASSLEVEL values minus 1 (in order to have them start at zero) can be used. Separate front vs back conversion type information will not be encoded in the EVENT_CLASS value, but it will instead just reside in the CONVERSION_TYPE column, thereby factoring out the redundant information that had been contained in previous implementations. This scheme will have several consequences:
- Separate IRFs for each class will need to be generated, but instead of generating the IRFs using events that have a minimum CTBClassLevel, as we currently do, the IRFs will need to be generated for significantly smaller numbers of events for which CTBClassLevel is a specific value, e.g., CTBClassLevel==1, CTBClassLevel==2, CTBClassLevel==3. In this case, only the IRFs for CTBClassLevel==3 would be the same as an original Pass 5 set (diffuse class). There would be substantially fewer events for CTBClassLevel==0 or 1. Here is a plot of the effective area for the front section for the three CTBClassLevel values using the AllGamma_v13r9p3_Lyon data:
The smaller number of events overall and the significant dearth of any events above 1 GeV will cause difficulties for characterizing the PSF and energy dispersion for the EVENT_CLASS 0 and 1 values.EVENT_CLASS
CTBClassLevel cut
curve
number of events
0
==1
red
0.27 M
1
==2
green
0.24 M
2
==3
blue
4.30 M
0,1,2
> 0
black
4.81 M
- Since each event has a unique set of IRFs, gtdiffrsp will only have to be run once regardless of the downstream selections on EVENT_CLASS.
- The gtselect interface will need to be modified. I propose two new sets of parameters to handle selections on the EVENT_CLASS and CONVERSION_TYPE columns separately:
Either one of these will produce a set of events that are the same as would be produced using "CTBCLASSLEVEL > 1 && CONVERSION_TYPE=0" in fcopy or fselect. It is anticipated that users will only want to specify a range of EVENT_CLASS values and not wish to make non-contiguous selections such as "EVENT_CLASS==0 && EVENT_CLASS==2". It is likely that users will not want to make selections excluding the higher event classes, so evclsmin may be all that is needed.Code Block gtselect evclsmin=1 evclsmax=2 convtype=0 gtselect evclsmin=1 convtype=0
- Separate IRFs for each class will need to be generated, but instead of generating the IRFs using events that have a minimum CTBClassLevel, as we currently do, the IRFs will need to be generated for significantly smaller numbers of events for which CTBClassLevel is a specific value, e.g., CTBClassLevel==1, CTBClassLevel==2, CTBClassLevel==3. In this case, only the IRFs for CTBClassLevel==3 would be the same as an original Pass 5 set (diffuse class). There would be substantially fewer events for CTBClassLevel==0 or 1. Here is a plot of the effective area for the front section for the three CTBClassLevel values using the AllGamma_v13r9p3_Lyon data: