Large telescope guiding

[gajjer]

I understand that the Jodrell Bank telescope uses gun turret racks from battle ships in the positioning of the telescope.

I assume similar arrangements are used on other big telescopes. How on earth do they get the positioning accuracy on such a large structure.

There must be enormous challenges with cutting gears to sufficient accuracy or is there error correction designed in.

I'd just be interested to know.

cheers

gaj

[JamesF]

I don't know how it's done, but your post prompted me to wonder what the focal ratio of the Lovell Telscope is.  So I looked it up.  The diameter of the dish is 76.2m and the focal length is 22.9m, which I reckon gives about f/0.3.  That's a seriously fast telescope

James

[jambouk]

I've just finished reading a biography of Bernard Lovell, and it is fascinating to learn about the role he played during WWII, and about the design and building of the radio telescope at Jodrell Bank; and learning about the gun turrets and the like!

There are copies in amazon second hand for 1p which is where i got mine from:

http://www.amazon.co.uk/gp/aw/d/0709017456/ref=mp_s_a_1_2?qid=1409034778&sr=8-2π=SY200_QL40

James

[Dave_D]

what most people don't know, is that Lovell actually wanted a 400ft dish as well which was meant to come after the MkII, there's a model of the 400ft in the MkII control room, at least it was when i worked there. sadly, government cuts shot the building of it down in flames :/

part of one of the axles snapped last year, it was a royal pain trying to find an engineering company that could fabricate a new one as nearly all of them couldn't use imperial measurements lol

[Peter Drew]

You get the impression these days that using professional microprocessing, even a cement mixer could be modified to track photographically.   

[ronin]

You get the impression these days that using professional microprocessing, even a cement mixer could be modified to track photographically. 

I now have a picture in my mind of potential imagers driving to the nearest Wicks or B&Q and pricing up cement mixers.

Also the perplexed look on the shop assistants when asked where they could plug in a PC, and does it take USB 2 or 3.

[gajjer]

Yep. All it would need is a mirror and an eye piece and you are away.

"Mom, that man next door is looking into his cement mixer again."

hee hee

cheers

gaj

[JamesF]

Not sure it would work with my cement mixer.  It only has an alt-az mount.

James

[DaveS]

People think battleship gun barbets (NOT turrets) as crude engineering, but they're not. They had to be as strong as a bridge built to Swiss watch precision. After all you're trying to lob a 1 ton shell 20-25 miles and hit a moving target subtending (I think) about a minute of an arc.

So well up to positioning a radio telescope.