Sky & Telescope - April 2023 QR - 70

ASTRONOMER'S WORKBENCH by Jerry Oltion
Roll-off the Whole Building
Try this simpler solution for a home observatory.
AFTER AN AMATEUR ASTRONOMER
has been observing for a while, setting
up their telescope each night and tearing
it back down in the wee hours, their
mind often turns to building a permanent
observatory. One of the most common
types is the shed with a roll-off
roof, wherein the top of the building
slides on rails onto a support structure
at the end of the building, leaving the
sky open for astronomy.
Not surprisingly, rolling off the roof
leads to several difficulties. First off, the
building needs to be custom-made with
a detachable roof. The outside support
structure has to be strong enough to
hold that roof, which means a pretty
robust framework that's equal in size
to the building. Then there's sealing it
against the elements and against intrusive
creatures while it's closed. And
when the roof is moved away, you still
have walls that block your view down to
a point significantly above the horizon.
California ATM Laird Stiegler
decided to solve all those problems
in one fell swoop, by leaving the roof
intact and rolling the entire building
away. Doing so meant he could use a
commercially available storage shed,
one that was considerably cheaper
than a custom-built shed and already
designed to be tight against vermin.
Moving an entire building is not
without its own challenges, but those
challenges are comfortably low to the
ground. Wheels at the corners roll
on U-channel tracks that can lie on
the surface or even be recessed below
ground level where they aren't a trip
hazard. If the telescope within is to
be permanently mounted, as Laird's
14-inch Celestron Schmidt-Cassegrain
is, then the building needs to slide
around the pier, which means cutting a
slot in the floor. That weakens the floor,
so it needs to be reinforced.
Laird solved that problem by setting
his building on a hefty platform made
of crisscrossed 2″ × 10″ lumber. He
added a set of wheels directly beside
the cutout, so they offer additional
support in the center. Laird reports
that he can stand right next to the pier
cutout and not see any sag to the floor
at all. The cutout piece is modified to
fit back in place when the building
is rolled over the scope, sealing tight
around the pier and against the rest of
the floor and the door.
The rollers are on fixed axles rather
than swivel castors. The building is
only rolling out and back, so fixed axles
work much better. Laird can push the
entire works with one hand. Its easy
movement would be problematic in
a windstorm, except the trapped pier
holds the building from moving when
it's buttoned up, and you don't observe
in high winds anyway. For added security,
however, Laird added tie-down
straps at the corners. The structure
is far less likely to move than a lightweight
roll-off roof.
The observatory rolls to the north,
leaving the east, south, and west wide
open for observing. It can be pushed far
enough away to allow polar alignment
or moved closer to provide a windbreak
on breezy nights. Its interior has plenty
of room for shelves, so Laird keeps all
his accessories inside where they stay
dry. The structure's large doors allow
easy access, so it's at least as convenient
pLeft: When closed, Laird Stiegler's observatory is just a commercial storage shed on a wheeled platform. Right: The entire building rolls away, leaving
the telescope on its pier with a view down to the horizon on three sides.
70 APRIL 2023 * SKY & TELESCOPE
ALL IMAGES COURTESY OF LAIRD STIEGLER

Sky & Telescope - April 2023 QR

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