A Large Portable Telescope for Astronomy Education

In 1997, the Museum of the Rockies and the Southwest Montana Astronomical Society in Bozeman, Montana embarked on a joint project to create a new outreach project for the region. Being located in a large rural state, the museum has already developed an astronomy outreach program that utilizes five inflatable Starlab Planetariums and two telescope teaching trunks with Edmund Astroscans. Another element was conceived to focus on deep sky observing for youth as well as the general public.

After receiving a grant from a local testamentary trust, a design committee with representatives of both organizations was created to identify a system that would follow the following criteria:

GOALS OF THE PROJECT Devise a portable telescope system for astronomy outreach. Special emphasis on school, scout, and youth groups. Make the telescope large enough to provide good views. Good quality optics and design for the telescope. Simple to set up and operate, but sturdy. After nearly a year of consultation with educators, amateur astronomers, telescope designers and manufacturers, the group decided to invest in a large-aperature Dobsonian-mounted reflector. Specifically, a 20" Starplitter II truss-tube Dobsonian was purchased with a Pegasus f-4.5 mirror. This allowed for enough aperture and quality to show considerable detail in many deep-sky objects, so the children's first impression in the telescope would be impressive (as opposed to hearing them say "that little fuzzy blob is all there is?!"). Considerable time was spent deciding on the focal length of the main mirror. A longer focal length tends to give better planetary images, suffers less coma around the edges, and isn't as susceptible to errors in figuring. But it makes the tube longer, requiring a taller ladder (and a scary situation for young children and shakey senior citizens). A shorter focal length yields a shorter tube and a wider field of view, but is more sensitive to mirror errors and coma at the edge of the field. In the end, the group compromised with an f-4.5 focal ratio and communicated directly with the mirror manufacturer to be sure we would get a good product (they even supplied us with a copy of the optical test results). To enhance viewing and make it easier to see, we also chose high quality 2" Nagler eyepieces, as well as a "Radian" eyepiece to provide excellent eye relief for those with glasses. The magnifying range was chosen to cover 42X to 254X, and a high quality barlow lens was added. Other items deemed crucial to the operation of the system included: Cloth Shroud Deep Sky Filters Laser Collimator Star Atlas STURDY Metal Platform Ladder Tarps, Cords, etc. The next important part of the system was customizing a trailer for carrying the telescope and accessories to the observing sites. The group opted for a 5' X 8' fully enclosed trailer, inside which we built hinged walls with foam and straps for holding the telescope box stable during transport. Logos for both organizations will eventually be added to the outside. The trailer turned out to be of excellent size for transporting the telescope, truss tubes, ladder, accessories, spare tire, and even other telescopes if necessary. For members to be allowed to use the telescope requires a training session by the Telescope Committee, but a prerequisite to this is having demonstrated experience with a telescope. The orientation takes operators through set-up, break-down, guidelines of use, care of the components, using the trailer, safety issues, and so on. For obvious reasons, liability and property insurance was arranged for the project. With the planetarium's connection to the university system, we were able to simply add this to our existing policy. The arrangement with the astronomy club is that in case of damages, it would share 50% of the cost of the deductible. FIRST YEAR IN REVIEW After its debut in summer, 1998 the telescope was used at 21 individual events (14 at remote sites). Total attendance was in excess of 2200 people, ranging anywhere from 10 to 300 people at each event. One of the most important goals was to try and supply a high "wow" factor, not just in the physical appearance of the telescope but in the impression the images made on the viewers. Based on our experience, this was most wholeheartedly achieved! A vast majority of observers had extremely positve and descriptive comments of what they were seeing. Important to note, however, was the need to have enough knowledgeable people at each event to provide enthusiastic and interactive narrative for what people are looking at, and to have naked-eye constellation ID going on at the same time. TYPES OF EVENTS Where did the telescope go? Originally the thought was that it would get used at just a few places. But in just the first year, we found a surprising number of applications: Schools Youth Camps Public Star Parties at the Museum Astronomy Society Meetings "Major" Star Parties Astronomy Day (including "sidewalk astronomy" events) Astro Fair (a co-sponsored astronomy festival at the museum) Yellowstone National Park Project (public viewing on three weekends over the summer) FUTURE PLANS The grant from the Laura D. Pasley Memorial Trust came to $10,000. All but about $1000 was spent on the process listed above. With some additional fund raising, the committee identified two things that would enhance the capabilities of the system: 1. Sky Tracking Ability (drive table or computerization) The ability to drive the telescope with the sky has obvious advantages in terms of avoiding the interruption of observing to manually reposition the telescope. The original budget did not allow for the purchase of a 20" scope on an equatorial mount, so we opted to purchase a drive table or alt-azimuth drive at a later date. 2. CCD Camera Once a drive system is in place, a CCD camera can be purchased in order to run imagery into the planetarium during cold winter night star parties (and it can get cold in Montana!). But the imagery can also be recorded for use at numerous special events and planetarium productions. 3. Regular Use at an Observing Site The astronomy club is actively looking for a dark-sky observing site that is reasonably close to town, not only for its own star parties but also to serve as a place that schools and youth groups can access for special sessions away from city skyglow. CONCLUSIONS Our results indicate that the program has been an overwhelming success! It has been a wonderful way to bring quality observational astronomy to the community, particularly the youth. The groups we have served thus far have been very impressed with the telescope's performance. Future demand dictates that we increase the number of qualified operators to set up and run the telescope (we have seven people right now; a good goal would be to have 10-12 for next year).