COMPTEL data

For COMPTEL data ctools operates also on event lists. An event list is a table where each row corresponds to a registered event and each column corresponds to a property of the event. Relevant properties are the event time, the Compton scatter direction and scatter angle, the Earth horizon angle, the energy deposits in the two detector layers, the x and y interaction locations in the second detector layer, the PSD and ToF channel values, the module combination and the rejection an veto flags. Event lists are provided as FITS binary tables. An example for a COMPTEL event list is shown below.

Metadata, such as the telescope pointing direction or any other information that may be relevant for data processing, is stored in the FITS header of the event list binary table. An example for the metadata that is included in the header of the COMPTEL event lists is shown below.

In addition, so called Orbit Aspect Data are needed for COMPTEL data analysis, which are presented in form a FITS table where each row corresponds to a so-called superpacket (a time slice of 16.384 s) and each column corresponds to orbital information for the given time slice. An example for a COMPTEL Orbit Aspect Data table is shown below.

Furthermore Good Time Intervals (GTIs) need to be specified, which for COMPTEL are given as so-called TIM files. Each row in a TIM file corresponds to a time interval of continuous data taking, and the USAGE column specifies whether the time interval should be used for science analysis. An example for a COMPTEL TIM file is shown below.