The AAVSO is happy to provide a copy of Bob Nelson's O-C files for Eclipsing Binaries for 2012. These files can be used for observation planning, and are a valuable resource for EB observers.
Thanks once again for Bob Nelson for providing this service to the EB community.
The late Bob Nelson developed over 5800 O-C (Observed - Computed) files for eclipsing binaries, all in Excel format, which we are hosting on our site. The purpose of this database is to provide information on period variation for selected eclipsing binaries (for astronomers interested in a particular star), as well as to determine the best elements for predicting future eclipses. These elements go into eclipse prediction software, like at Shawn Dvorak's site (Bob and others help provide updated elements for Shawn).
The AAVSO now distributes its published times-of-minimum data for eclipsing binary in single compressed files (.tgz and .zip), rather than as a searchable online index. For data on a specific star, unzip the compressed file, and search for the star's name among the included text files. These files contain updated publication information through November 30, 2005, the time at which the files were last updated.