We have determined new estimates of the plate scales in elevation for the three EUV cameras, and we have refined our technique for overlapping the images from the three cameras to form a single composite image. Our improved understanding of the geometrical characteristics of the EUV cameras comes from analyzing more than 5000 EUV images containing the Moon. Using the new plate scales leads to a maximum change of 1.0 degree in the position of a point relative to the center of the image. The difference between the separations of two arbitrary points in the EUV frame ranges from 0 to 1.6 degrees, depending on positions in the frame. More details are available at http://euv.lpl.arizona.edu/euv/otherdocs/brs030806.pdf.
These changes have been implemented by modifications to euv_imtool, to the programs that create FITS files from the UDF data, and to the appropriate VIDFs. Those who use UDF data directly should update their VIDFs.
A new version of euv_imtool, version 1.26, incorporates the updates. This software is available for download from the EUV anonymous ftp server (euv.lpl.arizona.edu), in the /image/software directory. We have also updated the automated FITS file extractor on the EUV website. If FITS images created before this revision are loaded by euv_imtool 1.26, the program will issue a one-time warning. For best results, obtain new versions of the FITS data files for the time period of interest.