The Astronomical Society of Greenbelt
Star Parties at Greenbelt Observatory

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ASG hosts about two star parties each month throughout the year on the Greenbelt Observatory hilltop. This location is considered to be the darkest open-sky site in Greenbelt. Star parties begin about one hour after sunset and continue for two hours or more. They can be cancelled without notice if it is raining or snowing, or if the sky is overcast. Our star party schedule is heavily weighted with dark-sky (no Moon) nights, so that we can more easily observe deep sky objects such as galaxies, nebulae and star clusters. We do, however, host about four "Moon nights" each year.

A "photosphere-warped" view
of the observatory interior

All of our scheduled star parties are open to the public and free of charge. Visitors are welcome to set up their own telescopes on the hilltop in the company of other telescope enthusiasts. Parking is available in the lot at the bottom of the hill. It's best if you park with your headlights facing the ballfield, so that as you are coming and going other visitors and members can preserve their dark adaptation as well as possible. Visitors with heavy telescope equipment can drive up to the top of the hill and, if they like, park their cars there if they are willing to stay parked for the duration of the star party.

Early arrivals setting up

The observatory is a little more than ten feet in diameter and about 13 feet tall. The telescope floor is about five feet above ground level, accessible via a ladder through a trapdoor. We can accommodate about a dozen visitors at a time. The telescope is a 1981 Celestron Schmidt-Cassegrain with a 14 inch aperture, mounted on a 2006 Meade LX200GPS computerized fork mount. We use a MallinCam Xtreme astronomical camera in lieu of eyepieces in order to capitalize on our ability, with this setup, to observe deep sky objects. We have found, over the course of time, that this is what our telescope does best. Some deep sky objects are visible with a three second exposure, but many require more time. We generally limit our star party observations to those requiring five minutes or less of exposure. We use our own stacking program to stack multiple three-second exposures in very short time, bringing out detail you wouldn't normally expect in a such a light-polluted area.

M51, Whirlpool Galaxy

We host "enhanced accessibility" star parties once or twice a year. On these occasions less mobile persons and their companions are welcome to drive up the hill. We set up a "ground station" with chairs near the observatory, with a computer monitor showing exactly what people up in the observatory are seeing. A ground station attendant is available to explain subject matter and answer questions.

M27, Dumbbell Nebula

We hope to see you soon, and then again! If you discover that you too are a telescope enthusiast and decide to join ASG, you will be welcome to participate in further adventurous ASG private astronomical projects.

Click here if you would like to see a collection of some of our favorite images, all taken by ASG members from locations in or near Greenbelt (except for one).

Last updated 19 June 2018, by Conrad Terrill
Questions? Email cwterrill - at -