Public Open Houses

Free open houses are held on Friday evenings at 8:00 p.m. (9:00 p.m. in summer when Daylight Savings Time is in effect) when CU classes are in session (during the spring, summer A & B, and fall semesters.)

SBO Public Event.

SBO public event on the observing deck.

Open houses are only held when the skies are clear. If you're not sure if we'll be open, check out our local weather with instructions for calling ahead. 

There is no charge for the Observatory's Open House nights ... the stars are free to everyone!

Sessions typically last from 1-3 hours, depending upon the weather, the quality of the night, and the enthusiasm and size of the crowd (if unsure of observing status call 303.492.2020). Please stop by anytime after we open and stay as long as you wish.

We also have tripod-mounted binoculars and the world's largest starwheel (well, at least we think it is) for identifying bright stars and constellations. Depending upon the staffing on a particular night, we may be able to offer you a chance to visit the 24-inch telescope ... that mysterious tube hiding hiding inside the dome ... as well additional smaller telescopes set up on the open deck for looking at the Moon and other bright celestial objects.

Most of our evening programs are hosted by the APS Department's graduate students, with an occasional faculty professor, researcher, local amateur astronomer, and/or undergraduate volunteer on hand.

Date of Observing Time of Observing Lunar Phase (% Illumination)
August 31, 2018 8:00 P.M.

79% Illumination

Waning Gibbous 70%

Waning Gibbous

September 7, 2018 8:00 P.M.

9% Illumination

Waning Crescent 10%

Waning Crescent

September 14, 2018 8:00 P.M.

24% Illumination

Waxing Crescent 20%

Waxing Crescent

September 21, 2018 8:00 P.M.

87% Illumination

Waxing Gibbous 80

Waxing Gibbous


89% Illumination 

Waning Gibbous 90%

Waning Gibbous

October 5, 2018 8:00 P.M.

19% Illumination

Waning Crescent 20%

Waning Crescent

October 12, 2018 8:00 P.M.

12% Illumination

Waxing Crescent 10

Waxing Crescent

October 19, 2018 8:00 P.M.

73% Illumination

Waxing Gibbous 70

Waxing Gibbous

October 26, 2018 8:00 P.M.

97% Illumination


Full Moon

November 2, 2018 8:00 P.M.

32% Illumination

Waning Crescent 30%

Waning Crescent

November 9, 2018 8:00 P.M.

3% Illumination

Waxing Crescent 0

Waxing Crescent

November 16, 2018 8:00 P.M.

56% Illumination

First Quarter

First Quarter

November 30, 2018 8:00 P.M.

47% Illumination

Third Quarter

Third Quarter

December 7, 2018 8:00 P.M.

0% Illumination

New Moon

New Moon