Friday, March 25, 2011

Don't mention The Cricket!!

Here are the 3 pairs of fibres from the SALTICAM auto-guider that feed the guidence & focus cameras. 


Some careful routing was needed to get them safely from SALTICAM, through the payload, past BVIT & over to the bay where the cameras are mounted.


With South Africa playing New Zealand in the quarter finals of the Cricket World Cup today, we could be forgiven for a rush of patriotism & the urge to set up a TV at SALT.  This turned out to be even more of a challenge than connecting up a hi-fi (let alone an 11-m telescope), but fortunately the technical problems spared us having to watch the Proteas' spectacular self-destruction.  Cough, cough, hack... sigh :(


One of the jobs to be done before Ockert went back to Cape Town was to weigh the payload & establish its centre of gravity.  All life-support had to be disconnected, including the glycol - which turned out to be under pressure!  The next scene opens with Vic & Ockert (both wearing glycol) holding hands over a bucket while they wait for pipe to run dry.


Luckily no harm done & so it was off to the jumgle gym for the rotating structure.


A set of load cells was used to attach the payload to the heavy frame at 2 points & the third point was hooked up to the dome crane.


Data was logged as the payload was tilted up in 10 degree increments.


The whole lot weighs about 220 kg & while it had its nose in the air, we had the chance to peer underneath.


From there you could see SALTICAM's front barrel & 1 of the mirrors that make up the Offner relay...


Happy with his haul of data, Ockert was off & the payload could return to its spot in the spectrometer room where Charl & Co. continue wiring & labeling everything.


Up on the tracker, inside the non-rotating structure, we got to take a scary look at the SAC from above.


Unfortunately there's not enough clearance in the hole that the ADC needs to locate in, so Eben had to use a dremel to buzz out some of the edges.  Much effort went into preventing the fine shavings from landing up inside the SAC.


Whew - still looks clean down there!


The last task for the day was to close up the payload & check whether, with everything running overnight, the glycol system manages to maintain the temperature spec (which requires the whole lot to remain within +/- 2 C of ambient).


Up on the tracker, the payload bays that don't have hatches will be covered by the walls of the non-rotating structure.  Sheets of corex were taped over those parts to simulate the insulating effect.


After 2 hours, all seemed well - other than the frame-transfer/shutter muscle box for SALTICAM which was a few degrees above ambient.  The test was left to run overnight.

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