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Dew heater straps and shields

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Grant Privett's picture
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Dew heater straps and shields

I'm preparing to use an 11" Celestron RASA (as in balanced on mount today) but as I am normally a Newtonian or RC observer, I wondered what sort of dew heater strap or shield is generally used by people using SCTs of this sort of aperture?

Am thinking of an 8" long polystyrene shield (black lined) and a standard Kendrick 11" heating strap. Any thoughts?

Also, I am toying with the idea of co-mounting this with a standard C11. Does anyone make brackets that could handle that? Was intending to ask round at Astrofest.

Jeremy's picture
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Dew heater straps and shields

Grant,

I use a standard dew heater band on my C11, near the corrector plate. I used to have a dew shield as well, but it was a pain as I kept dislodging it as I moved around the obsy. Moreover, if I needed to cap the telescope during breaks in observing, or to produce CCD dark frames, I had to take the shield off, put the cap on and then reverse the operation to start observing again. Too much of a hassle!

I look forward to seeing your results with the RASA.

Jeremy

Grant Privett's picture
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Will post

Will post something here once I have it. Its going to be a stupidly large field of view compared to the f8 Altair RC.

From your picture you use a dome. Does that save you some of the dewing grief?

Jeremy's picture
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C11 dew

possibly, Grant. But the corrector plate is obviously still exposed as it looks out of the dome slit.

Jeremy

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Dew heater straps and shields

Grant,

I use a dew shield with a built in dew strap on my C11. I can't remember where I got it from, but looking online it seems they cost in the region of £100 now!

No idea about the dual mounting for such big [heavy] scopes, but clearly can be done:

http://www.mikesastro.com/equipment/lx200r/C11vsLX200R.html

James

Grant Privett's picture
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Dew and C11 RASA

Have seen some C11 size heaters for £50 but it didnt quote the power...

Useful webpage! Followed a link on that site and have asked them for a quote on the co-mounting bars.

andrew.j.smith1905's picture
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Dual Mounting

Grant, I suspect the bracket will be the least of your troubles with a dual mount. That is a big load for an EQ6 if that is the mount you intend using. 

Regards Andrew

Grant Privett's picture
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Weight

The C11 RASA and C11 SCT come in at about 32kg, with CCD and filter wheel, call it 35kg. Allowing 50% margin,  ~50kg. Thats less than half the system rating of 109kg. Am hoping we are okay, though I would like to be able to slew at 1 deg/sec to keep up with things like the ISS. 

A Planewave L600 would be nice but without a Lottery win.....

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W&W Dew Heaters

W&W sell dew heaters, and have attended our B2B workshops and other meetings, and were at the IAS. 

Website is https://dewheater.com 

No connection except I bought one for a camera lens.

Callum

Grant Privett's picture
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W&W

I've not come across that company before. Prices seem reasonable/good.