More Design Considerations

In considering various options for the observatory, I noted a number of other important design considerations. My notebook:

Pier Height

• The pier should be of a height that will place the mount approximately where it is when tripod-mounted, for familiar ease of access.
• Assume when I say “height” I mean “height above the deck surface”. In fact it needs to be taller by the amount of the deck’s height off the ground since the height reference will be the deck surface.
• In fact, I might like the pier a little higher than the normal tripod height, for two reasons:
  • A little extra height would give a fractional improvement to the amount of sky I can see over the high hedge that surrounds the property; and
  • Since I’ll be doing mainly imaging, the loss of convenient eyepiece access is not very important.
• However, pier height will be constrained by:
  • Stability of the pier
  • Geometry of the dome – need to ensure it will close securely with all gear mounted.

Deck Height

I plan a low, raised deck to surround the pier and provide a mounting surface for the dome. The deck should be level and stable enough for comfort and long life, but sturdiness isn’t important for optical purposes since the pier will pass through the deck without touching it and be mounted directly into the ground. So moving around on the deck will not disturb the pier. Deck height considerations:

• I’d like enough height to be clear of the first few weeks of snow accumulation in winter. Eventually the snow in the yard builds up to 1 - 1.5 metres deep, but in the early winter it spends significant time less than 20 cm deep. Clearing at least the early-season snow will allow the observing season to be easily prolonged.
• Low enough to minimize visual impact as seen from the house, and be as unobtrusive as possible from outside the property.
• Decks 60 centimetres in height or higher (the bylaw is written as “24 inches”. What country is this again?) require a building permit. Under 60 cm doesn’t require a building permit.

Deck Shape and Size

The deck will hold a SkyShed POD with 3 add-on storage bays. The SkyShed web site gives minimum dimensions for this setup as 295cm × 338cm. I sketched options using other shapes (hexagons etc) to better optimize the footprint, but fear of complex construction eventually lead me to plan a simple square surface.