work progresses on the 13"

[videoguy]

Bird, That's a brilliant image of Tycho on your site!

[bird (Anthony Wesley)]

Thanks Steve - was a complete fluke, as most of these things are. It was taken at about 5.30am, only 20 mins before sunrise - I'd been imaging Jupiter and had just finished and decided to pack up but the moon was nearby so I moved over to it and grabbed a few runs including that one.

The scope was properly cooled, the moon was at the zenith and the pre-dawn air was very steady. Turned out to be a good combination :-)

regards, Anthony

[seeker372011 (Narayan)]

Bird;
it was great to check out your site. Love your lunar composite project

my personal favourite is your Clavius shot

who needs an Orbiter eh?

[mch62 (Mark)]

Hi bird , interesting idea , but have you used a conical yet as you may find that you may not need to go to all the trouble with the peltiers.

I live out side of Ipswich QLD , which has a reputation of 20-24deg swings from min to max not out of the ordinary , summer or winter and have not had much of a problem with cool down or keeping up with temp drop with my conical.
I do have a large piece of aluminum for the mounting stud and plate like in your diagram and find very little heat turbulence from the mirror strait from the shed and within 1/2 hr the mirror has reached equilibrium.

I also have a very open truss tube .

When I was concidering a mirror I also looked into the use of peltiers and fans but Rob Royce recommended trying with out first .
I never worried about a cooling fan as it has not been necessary.

I keep in touch with a couple of R.Royce's other customers who found a similar result and 2 of them live in the north USA.

May be try with out the peltiers first and do a comparison after wards??

just a thought

Mark

[bird (Anthony Wesley)]

Hi Mark, I tried the other cooling options first, and went to the peltiers only after they failed :-(

The conical will be a lot better than a "normal" mirror, it only has about 70% as much glass as a full thickness 13.1" mirror would have, but that's still more glass than my current 10" mirror so I can't see the problem getting any better... I just hope I can stop it from getting worse!

I know Ipswich, I grew up in Glen Innes just south of there...

The problem I'm having in Canberra is that the temp will keep dropping by about 2 degrees per hour from sunset through to 2 or 3am. There's no way my mirror will track that without aggressive cooling - maybe your conditions are better up there, if the temp drops fast and then stabilises you'll be ok.

regards, Bird