CALDB Internal Release Notes Version 1.5 CALDB Date: 2000-09-14T20:30:00 I. CHANGES: We have updated the 12 pcad alignment (CALALIGN) files to include improved FID light positions in the second extensions to each file applicable to ACIS-I. This corrects a problem with a certain few OBSIDs which have non-standard FID light configurations, resulting in an error of 2 arc seconds or more in the coordinate values derived for the events. Some OBSIDs with large SIM offsets are also improved by this change. The non-standard FID light problem is discussed on the CAVEATS page: http://asc.harvard.edu/ciao/caveats/aspect4.html See the acis-I observation list at http://asc.harvard.edu/cda/fid.txt. If your OBSID is in this list, and you have coordinate errors in your delivered products as described above for ACIS-I, the new files in processing or reprocessing will correct for this effect. II. The changes are effective in all processing completed after DATE=2000-09-14T20:30:00. The DATE keyword, which is the processing date, is what is important here. Also, resulting pcad files will have one of the following files listed as the alignment calibration file: $CALDB/data/chandra/pcad/bcf/align/ pcadD1999-07-19alignN0002.fits pcadD1999-07-29alignN0002.fits pcadD1999-08-08alignN0002.fits pcadD1999-08-18alignN0002.fits pcadD1999-08-28alignN0002.fits pcadD1999-09-07alignN0002.fits pcadD1999-09-17alignN0002.fits pcadD1999-09-27alignN0002.fits pcadD1999-10-07alignN0002.fits pcadD1999-10-17alignN0002.fits pcadD1999-10-27alignN0002.fits pcadD1999-11-06alignN0002.fits Each one of these files replaces the N0001 version.