With Pass 8, event_types are introduced. Even though these are essentially a generalization of conversion_type (i.e., front vs back converting events) in that the event types partition the data into distinct subclasses which have their own effective area, point spread, and energy dispersion functions, in Pass 8, there are alternative partitions for a given class. For example, the Pass 8 SOURCE class selection can be partitioned in one of three ways: into front vs back converting events, into events belonging to one of 4 "PSF" subclasses, or into events belonging to one of 4 "EDISP" classes.
The Pass 8 event_class and event_type descriptions and usage are described in the following links.
The event type partition has been added as an option for gtobssim. Examples for P8R2_SOURCE_V6:
gtobssim irfs=P8R2_SOURCE_V6 evtype=none gtobssim irfs=P8R2_SOURCE_V6 evtype=PSF gtobssim irfs=P8R2_SOURCE_V6 evtype=EDISP |
evtype=none is the default, in which case the application will use the front/back partition, consistent with pre-Pass 8 behavior.
For evtype=[PSF,EDISP], DSS keywords specifying the event_type partition that was used will be written to the FT1 files that are produced. These keywords will show the bit pattern that would be used to mask to obtain the corresponding partition, e.g., for evtype=PSF:
DSTYP2: BIT_MASK(EVENT_CLASS,128,P8R2) DSUNI2: DIMENSIONLESS DSVAL2: 1:1 DSTYP3: BIT_MASK(EVENT_TYPE,60,P8R2) DSUNI3: DIMENSIONLESS DSVAL3: 1:1 |
Here 60 = 0b111100, the binary representation of the mask with bits 2-5 set. Note that the event_type DSS keywords will be omitted for the front/back partition.
For both evclass and evtype, the user must specify the integer corresponding to bit-mask that selects the desired events within a single partition:
gtselect evclass=128 evtype=3 # P8R2_SOURCE_V6, front and back (i.e., all) events gtselect evclass=128 evtype=1 # P8R2_SOURCE_V6, front-only events gtselect evclass=128 evtype=60 # P8R2_SOURCE_V6, PSF[0-3] (all) events gtselect evclass=256 evtype=960 # P8R2_CLEAN_V6, EDISP[0-3] (all) events |
The evtype=[3,60,960] selections all return all of the events, but they also specify the irfs corresponding to the event_type partition selected. This information is written to the DSS keywords and read by downstream tools.
One can also do
gtselect evclass=none evtype=none |
in which case, no event_class or event_type cuts are applied and the DSS keywords associated with those cuts would not be added. This will allow one to use an FT1 file from the astroserver as the common input file for different evclass and evtype selections.
The output will be expanded to indicate event_type partitions:
$ gtirfs <...output for P7* irfs...> P8R2_CLEAN_V6 ( = P8R2_CLEAN_V6::BACK + P8R2_CLEAN_V6::FRONT ) P8R2_CLEAN_V6 (EDISP) ( = P8R2_CLEAN_V6::EDISP0 + P8R2_CLEAN_V6::EDISP1 + P8R2_CLEAN_V6::EDISP2 + P8R2_CLEAN_V6::EDISP3 ) P8R2_CLEAN_V6 (PSF) ( = P8R2_CLEAN_V6::PSF0 + P8R2_CLEAN_V6::PSF1 + P8R2_CLEAN_V6::PSF2 + P8R2_CLEAN_V6::PSF3 ) P8R2_CLEAN_V6::BACK P8R2_CLEAN_V6::EDISP0 P8R2_CLEAN_V6::EDISP1 P8R2_CLEAN_V6::EDISP2 P8R2_CLEAN_V6::EDISP3 P8R2_CLEAN_V6::FRONT P8R2_CLEAN_V6::PSF0 P8R2_CLEAN_V6::PSF1 P8R2_CLEAN_V6::PSF2 P8R2_CLEAN_V6::PSF3 P8R2_SOURCE_V6 ( = P8R2_SOURCE_V6::BACK + P8R2_SOURCE_V6::FRONT ) P8R2_SOURCE_V6 (EDISP) ( = P8R2_SOURCE_V6::EDISP0 + P8R2_SOURCE_V6::EDISP1 + P8R2_SOURCE_V6::EDISP2 + P8R2_SOURCE_V6::EDISP3 ) P8R2_SOURCE_V6 (PSF) ( = P8R2_SOURCE_V6::PSF0 + P8R2_SOURCE_V6::PSF1 + P8R2_SOURCE_V6::PSF2 + P8R2_SOURCE_V6::PSF3 ) P8R2_SOURCE_V6::BACK P8R2_SOURCE_V6::EDISP0 P8R2_SOURCE_V6::EDISP1 P8R2_SOURCE_V6::EDISP2 P8R2_SOURCE_V6::EDISP3 P8R2_SOURCE_V6::FRONT P8R2_SOURCE_V6::PSF0 P8R2_SOURCE_V6::PSF1 P8R2_SOURCE_V6::PSF2 P8R2_SOURCE_V6::PSF3 <...output for remainder of P8R2 irfs...> |