In the foreground, you see the subfloor slab for the observatory building. The block rectangle behind it is the stairwell leading down to the basement. Interrupting the slab are the two telescope footings topped with the base plates to which the piers will be attached.
Behind the stairwell you can see the footings for the columns which will support the roof when it is rolled off. The forms are in place and the concrete caps have been poured, into which we set the anchor bolts. Doing it this way gives us a smooth surface on which to set the columns and allows us to easily bring all the footings to the exact correct height. We left the form boards in place after pouring the concrete to allow it to cure a bit more slowly.
Notice the clear blue sky!
All of the anchor bolts for the building are encased in concrete now, which means their locations are rather permanent. An order has been placed for the observatory building's steel skeleton, so it's time to get going on the siding.
The slab you see here is the subfloor of the observatory; its function is mainly to serve as a footing for the steel frame of the building, but it also serves as a rodent barrier. It is actually nearly two feet below the final ground level, which will help keep it cool and reduce any thermal effects. Block walls will be built between the steel columns to bring the remainder of the foundation to final height.
Note that the two telescope footings are offset east-west from each other (this picture is looking north); this allows the north telescope to have an unobstructed view to the south without worrying about the south telescope being in the way. You can also see, level with the slab, that the footings are separated from the slab by one-inch-thick sheets of styrofoam -- this will keep vibrations in the building from transmitting through the slab to the telescopes.
Next up: Raising the steel
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Terry R. Friedrichsen
terry@venus.sunquest.com