If you're uncertain as to whether or not we'll be open, you can call the Observing Deck at 303.492.2020 (no earlier than 30 minutes before the scheduled starting time) before making the trip to the Observatory. You may or may not get an answer, depending upon whether a host has arrived and/or whether s/he is able to take the time to get to the telephone.
The telescopes are outside in an unheated area - so be sure to dress appropriately and warmly! When in doubt, wear lots of layers!
For Public Open Houses, groups of 8 or more individuals must make reservations by calling 303.492.6732 at least 3 days in advance. If you're interested in scheduling a field trip or tour please complete the request form.
It takes about 20 minutes or more for an individual's eyes to become dark-adapted (the pupils slowly enlarge to accept more light), but it takes only a fraction of a second to lose that night vision by glancing at a white light.
Consequently, if you wish to bring a flashlight (which is not necessary), be sure it is covered with a red filter. Dim red light does not significantly affect one's night vision (and in fact, you'll notice that the Observatory at night is lit only with red lighting for this very reason).