Public Observing      

Next Scheduled:

9:00 PM - 11:00 PM

Due to the ongoing restrictions and health concerns due to COVID-19, public observing is cancelled until further notice. We hope to welcome you back in person soon; please take care in the meanwhile.

The department of Astrophysical Sciences at Princeton University holds monthly informal open houses for the purpose of observing the night sky. Weather permitting, we can usually look at planets, nebulae, open clusters, globular clusters, and galaxies through a 12” Schmidt-Cassegrain telescope. We (being the students and postdoctoral fellows in the department) are also quite happy to answer any astronomy-related questions you might have.

It is an open house, so come anytime during the above interval and stay as long as you like until closing. We will update the above calendar in the afternoon the day of scheduled public observing to indicate whether it is on or canceled due to weather, but there is no guarantee, of course, that the weather will not change between then and the start of the session, so please check the "Status" (above) on this website before you set off. For a last-minute check please look outside before leaving your house; if you can’t see any stars, neither can we!


WHERE: Peyton Hall, Ivy Lane, Princeton University. From the street entrance, come in and turn right down the hall. Find the stairs on your left just before the end of the hall and go upstairs to the telescope room.

WHEN: Open houses this year will *usually* be on the second or third Wednesday (sometimes Tuesday) of each month (in the event of cloudy skies, bumped *usually* to a week later). Sometimes these days/times will be moved because of competing campus events or the availability of people to run the open houses, or particularly favorable or unfavorable phases of the moon, so watch this website. We will try to give as much advance notice of changes as possible. The status of the upcoming observing session is shown above, and the full schedule for the semester is posted below.

For more information, contact Samuel Yee at

Note: We usually decide whether the weather will be good enough to hold our observing session by about 3:00 PM on the day in question. Please check this site after that time to make sure that we’re going ahead, and please check it again immediately before you come! Sometimes we make mistakes, and we cancel when the weather is clear, or are forced to cancel at the last moment because of unexpectedly bad weather. Apologies in advance for all such mistakes. If you’re really interested, check the Clear Sky Chart tab (the same astronomy weather info we use to make such determinations).

Spring-Summer 2020 Schedule

Date Start time  Type of session