YALO nightly observing logs are filed by the local date at the start of the observing night. For example, to find the observing logs for the night that began the evening of 1999 June 12 and ended at sunrise on June 13, you would look at the log dated 1999 June 12.
We began keeping automated observing logs on 1998 June 4, and the last night of YALO operations was 2002 September 24.
Observing logs are generated automatically by the AutoLog program running as part of the data-taking system.