Observing logs are organized by month. Within each month the logs are filed by "Observing Date", which is defined as the local date at the start of the observing night. For example, to see what was observed during the night that began at sunset on 2001 June 12 and ended at sunrise on June 13, you would look at the log for 2001 June 12.
Logs are updated automatically at 10am Eastern Time.