AP Observatory on roof patio?

[APushkin]

Would a patio on a roof of 2 story wooden house be stable enough for AP? If it was already built I would have an easy way of testing it but it is something I'm just considering and I wouldn't want to build something that will end up not working at all.

[skinnyonce]

Since you need to build it.. take into account flexture and walking around vibrations I would if you can isolate the scope from the rest of the deck keeping the scope from feeling any effects of wind and vibration sources as it were.. cars, music, people, etc etc...

[cbrucker]

Just up the live load value to take into account that you don't want any vibration. You would do that by decreasing the span between the joists for the decking. Also use larger joists. For example instead of 2 x 8's use 2 x 10's

[jimt]

Besides the vibration issue, you are going to have a lot of problems with heat radiating from the roof after the sun goes down. Ever drive down the road and see the water spot illusion? That is caused by heat radiating from the surface of the road.

With your roof top setup, you will be trying to observe the sky through that. You most likely will never achieve good seeing conditions due to that.

I set up an etx 80 on the roof of my house to test that theory. The seeing was good, but when I set up on the roof, even at low power (about 33x) the Moon was bouncing around all over the place. Seriously it looked like you put a picture of the moon in the bottom of a pot of boiling water.

Don't take my word for it. Do some research on your own to see what you come up with. Talk to someone else that built a roof top observing platform.

Good luck
Jim

[fogfire]

I think the normal vibration of the house.. can even be an issue..

There is a guy selling his gear that was in a roof-top observatory..
Note the 2 story pier he poured for this..

Astromart Classifieds - Telescope - Reflectors - LX 200 16" MEADE and DOME

[DaltonSkyGazer]

The two major issues brought up are the vibration induced from within house to the structure, which can be overcome with great expense and planning. I have seen home observatories where concrete block was used to isolate the pier built from ground level up to the 2nd story of a home at great cost.

The heat currents and such coming off of hot surfaces or from exhaust pipes mentioned is the other major issue. If the observatory portion was located at a corner of a house away from these sources and ones viewing did not happen over the house, then they would be less an issue. You also have internal heat coming up from the actual observatory floor to deal with which is from structure of the house which acts as one giant heatsink.

It is most definetly possible, but involves great cost and a high deal of planning to reduce the vibrations. It is far easier to build a separate observatory. Browse around Bill Arnet's Nine planets org observatory list, there are many concepts in there with backlinks to some websites showing design and builds of these type of observatories. Some of them document the design considerations in great details for those attached to a home.

[ericgraham]

I had a roof top observatory many years ago and while I didn't do AP I had no real problems with either vibration or heat messing up the seeing. I expected bad problems with both, but liked the convenience of climbing out a hatch and being able to start observing in five minutes.

Eric