Stacked Observation Detections Exposure Map (exp3.fits)
The stacked observation detections exposure map file consists of a single FITS format file for each set of stacked observations and science energy band that results from catalog processing. These exposure maps are generated by combining the exposure maps generated from the corresponding instrument map at the equivalent monochromatic energy for each science energy band for each individual observation in the stack set. Individudal exposure maps are computed by applying the aspect histogram sampled at 0.5 arcsec resolution; ACIS exposure maps are blocked by 1 and HRC exposure maps are blocked by 2 in SKY coordinates.
![[NOTE]](../../imgs/note.png)
The exp3.fits exposure maps are created as shown in the CIAO thread "Multiple Chip ACIS Exposure Map."
Stacked ACIS Exposure Map
![[Thumbnail image: Stacked ACIS exposure map]](imgs/acisfJ0035508m433654_stk_field_exp3.png)
[Version: full-size]
Stacked ACIS Exposure Map
An example of a stack of ACIS exposure maps for a given set of observations.
The full-field exposure map FITS file is named: 〈i〉〈s〉〈stkpos〉_〈stkver〉N〈v〉_〈b〉_exp3.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 〈b〉 is the energy band designation.