Fixing SPT

broken cable

Much of this week, I’ve been helping fix a problem out at SPT. A cable in the “azimuth wrap”, which is essentially a springy spiral cable tray to get hoses and cables into the left-right moving part of the telescope, had shifted such that it rubbed on a support and wore through.

Getting to the “az wrap” is fairly easy, but there’s not much space around it to work, it’s noisy (mainly the chirp of pulse tube coolers), and there’s lots of chilly steel involved. The wrap lives in the conical base of the telescope, which is heavy steel that goes straight to the outdoors above and below.

matt working on az wrap

Fixing it involved finding some parts, a little bit of wiring, making some new parts to prevent this sort of problem occurring again, and a fair bit of wrestling the wrap back into shape.

The circuit that broke is a 5 wire, 3 phase power feed; four of the wires were broken all the way through, and unfortunately all the insulation is black as it’s special cable. So, there was a bit of investigating involved to figure out where the cables were meant to be connected.

wiring at spt

We got things put back together and the telescope back to observing yesterday, but I think there is a bit more tinkering with this in my future. We want to improve some parts of the wrap to make it a bit more reliable, and that’s also a good excuse for me to get away from the computer.

We also had some nice aurora yesterday, with plenty red. I froze my hands pretty well taking pictures of these, but found that I can actually get real-time video of aurora when I’ve got my 50mm f/1.4 lens on the 6D – crazy! The fuzzy grey blobs in the sky near the centre of this photo are the Small Magellanic Cloud and Large Magellanic Cloud.

aurora from SPT roof



About ianrrees

Nerdy guy.
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One Response to Fixing SPT

  1. Cool! Great shots.

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