CIAO 4.12 has a new FOV algorithm which is available using method=convexhull which provides for a tighter fitting FOV. However, for observations where there are large changes in the boresite offsets (DY and DZ columns in the aspect solution file) the FOV may be too tight; the FOV may then inscribe the observed data.
Bugs fixed in CIAO 4.12
The following is a list of bugs that were fixed in the CIAO 4.12 software release.
FOV contains polygons for all CCDs listed in the DETNAM keyword.
Incorrect results when running with reprojected datasets without supplying the aspect solution file.
If the aspect file is omitted, the original tangent point is used with will result in a shift of the field-of-view region file with respect to the data.