Star Gully Design Considerations

Compromises

• Space is at a premium. The 8' x 8' profile is enough space to store Equinox, and for me to be inside and observe with it. However it is not even big enough to allow the telescope to swing fully in every direction (Equinox's swing radius is ~52", and the walls are only 48" away from the center of the structure where the scopes sits).

• The low E-W walls are a compromise to make up for not being able to fully swing Equinox, so I lose some protection from light and wind. By not fully lowering the roof panels, I can protect myself somewhat, but restrict my observing closer to zenith.

• The high N-S walls cut-off my sky in those directions, but the north is dominated by a light dome from Logan, and I seldom observe below Polaris, which I can still see. There is a light dome from Ogden and Salt Lake City in the south, but I often venture into this part of the sky, particularly in the Summer Milky Way. I think I can get targets I might normally go after as they rise in the SE sky.

• Certain design requirements for Starlight Basin Observatory were not possible with Star Gully Observatory, notably having a full size entry door and being able to stand upright inside.

• Because I was trying to conserve money, the materials used in Star Gully Observatory were not the materials I would have normally chosen for a permanent structure. In particular, the observatory is skinned with 1/4" OSB sheet, with no siding and only a layer of exterior paint; the walls and roof studs are all 2x3 lumber rather than 2x4 lumber; the roof panels are PVC panels rather than metal panels; the frame of the floor is not treated wood (though it is covered with a layer of Tyvek, and raised above ground level on cinder blocks).

Early Concepts

• Equinox had to remain set-up and protected from the elements.

• The observing area had to be free of snow, or at least easy to clear of snow in very short order.

• A small Rubbermaid garden box (usually meant for shovels and rakes and such) that would fit Equinox, next to a tarp staked to the ground that coule be peeled back to remove snow from a bare patch of ground. Abandoned: We weren't sure you could "peel back" a thick fall of snow without shoveling, and we were pretty sure pocket gophers and the like would make their home under the tarp all winter.

• A tent of tarps over a rope between two poles, with Equinox underneath. Abandoned: We weren't sure we could close off the ends to keep the snow out and off of the scope, nor were we sure such a structure would hold up to the winds comeing through with a storm.

• A light geodesic dome skinned with tarps, like people build for greenhouses or Burning Man. I could simply flip the dome over onto the snow when I observe, then put it back over the scope when I'm done. Abandoned: We weren't sure I could easily stake it and secure it to the ground during winter.

• A 4x4x8 box that holds Equinox horizontally in storage. The box would completely unfold flat on the ground to form an observing surface. Abandoned: We weren't sure unfolding onto the snow or bare ground could be made to work.

• A wire dog kennel, with the sides covered in tarps. Abandoned: There was no way to open the kennel to the sky, and they cost $300 for something about 3'x5'. It was the discussion about this option that put us directly on the path to the current concept.

Plan & Materials

Construction started 25 October 2009. The basic frame was built in one day, painting took another day, and erecting the structure took a third day. Figeting with the roof support lines, the door, and the trim took several days of tinkering over the course of a couple of weeks. The site is located just east of the footprint of Starlight Basin Observatory. The total cost of materials was $500, not including the paint and interior floor mats (UPDATE: $600, if I include the added cost of the counterweighting system that was added on).

The 8'x8' size was chosen to minimize the amount of cutting that had to be done to expedite construction from dimensional lumber. The basic plan was worked out on three sheets of paper at Lowe's in Logan on 24 October 2009, as I was buying materials (as soon as the inspiration struck, we got on it!). Those plans are shown below; everything fit in the back of my truck in one load.