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Re: Operating proceedures for "The Dish"



At 05:25 PM 11/1/2001, Murray Peterson  VK2KGM wrote:
>can have a look at the online operating instructions at 
>http://www.parkes.atnf.csiro.au/

My shack has some unusual operating quirks, but these guys...

(short extract from the "observer's guide"...)
The laser is beamed towards a plane mirror in the top of the master 
equatorial telescope, and when the dish and the telescope are aligned to 
within one arc minute, the reflected beam falls on the detector diodes. The 
offset of the laser beam from the centre of the array is read by the servo 
computer which, when the offset (error) is below one minute of arc, closes 
the servo loop, causing the dish to accurately follow the movements of the 
telescope. The dish is then said to be "locked" to the master equatorial 
telescope. Only then can the radiotelescope be driven in right ascension or 
declination. Errors during tracking and scanning are typically less than 
ten seconds of arc.

An occasional problem is the presence of bugs and moths, which are 
attracted by the laser light and can cause the telescope to lose "lock" if 
they fly through the laser path. Cobwebs can also build up along the laser 
path and cause similar problems. An UV insect trap is located in the ME 
room to minimise these problems but it may be necessary on occasions to 
check the ME room for excessive numbers of insects, turn off any 
unnecessary lights that may be attracting them, and remove any cobwebs from 
the laser path (using the feather duster left near the ME for this purpose!)


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