The reservation calendar works on "Observatory Hours". These are similar to the operational hours at a local grocery store or shop, in that we have a designated open and close period each day.
However, due to the nature of astronomy, the open and close times end up on two separate days, which can lead to complications when dealing with a calendar based reservation system.
So, what we have done, is to structure each column as an open to close period. That is, each column of the calendar represents Observatory Open on the Night listed at the top of the column, through Observatory Close the next day.
This means that if you are looking at the column labeled, Tuesday, February 17, 2015, that column will include reservations that are set to begin any time after Observatory Open on Tuesday, February 17, 2015 THROUGH Observatory Close on Wednesday, February 18, 2015.
If you create a reservation at 2am inside this column (labeled Tuesday, February 17, 2015), you will be creating a reservation for early Wednesday morning, February 18, 2015 at 2am.
We realize this can be odd, but both the reservation and ACP have a lot of technical "problems" when they try to wrap from one date to the next. If we were to end our day at midnight each night, any reservation currently running would also be aborted to make way for the new day so we have opted to instead end the day slightly later to keep all the systems operating as smooth as possible.
If you have any questions, please contact support, and we will be happy to clarify.