Source Region Per-Stack Detections Events Files (regevt3.fits)
The source region stack events file consists of a single FITS format events file for source regions of each stack of observations; it is the result of applying a rectangular SKY region filter to the corresponding full-field event file for the stack of observations. The rectangular SKY region filter is equal in size to the background region of interest (ROI) corresponding to the detected source region.
The good time intervals (GTIs) associated with source region event data are included as additional FITS HDUs (CXC Data Model blocks) in the source region FITS event file. For an events file containing ACIS data, there is a GTI block for each ACIS CCD included in the source region; there is a single GTI block for an event file containing HRC data.
The stacked observations region events FITS file is named: 〈i〉〈s〉〈stkpos〉_〈stkver〉N〈v〉_〈r〉_regevt3.fits
where 〈i〉 is the instrument designation; 〈s〉 is the data source; 〈stkpos〉 is the position component of the stack name, formatted as "Jhhmmsss{p|m}ddmmss"; 〈stkver〉 is the 3-digit version component of the stack name, formatted with leading zeros; 〈v〉 is the data product version number; and 〈r〉 is the region ID, formatted as "rnnnn", where nnnn is the 4-digit region number, formatted with leading zeros.