7.5 Caveats

• At present the CIAO tools dmcoords and probably mkarf and mkacisrmf produce incorrect results¹² when run on data that have been reprojected. For this reason, AE requires that ALL EVENT LISTS, ASPECT HISTOGRAMS, AND EXPOSURE MAPS MUST BE EXPRESSED IN THE ORIGINAL COORDINATE SYSTEM OF THE OBSERVATION, NOT IN A COORDINATE SYSTEM REPROJECTED TO MATCH A MASTER OBSERVATION. This is the fundamental reason that source positions are given to AE in celestial coordinates, rather than in a ``master'' sky-pixel coordinate system.

• When the path to the directory in which you run AE gets too long the path AE must put in the PFILES environment variable gets too long for the addrmf tool to handle and addrmf ungracefully dies with a ``core dump'' message. Similarly, the fitting scripts can fail on a call to fstruct when the path in PFILES gets too long.