Thursday, June 28, 2012

Day 32, 6/28/2012 -- The gondola returns

Today was another full day in the high bay. The big news is that the gondola has returned from powdercoating wearing its new outfit of lustrous white powdercoat. Britt and Michele spent some time this afternoon removing the masking from the holes we didn't want coated. In other gondola news, KyleH and Andrei worked on the triangle's shock absorption system on the BTS (which is intended to prevent the triangle from crashing down into the telescope on termination and landing). Michele also started disassembling our spare elevation actuator in order to degrease it and then regrease it with low-temperature grease (we use Dow-Corning Molykote33 Light, an aviation grease).

On the receiver side, we started getting set up to do polarized spectral response measurements to map out the HWP's phase response as a function of frequency. So, the HWP was ungripped, I helped Jeff make some electrical isolation pieces to isolate the motor from the cryostat, and the HWP was set spinning. It was at that point that we found the HWP position encoder readout boards weren't really reading out anything at all. After a few hours of troubleshooting, Jeff installed a spare ADC board (the so-called "mezzanine" boards of the DfMUX system) and everything worked again. We have some theories as to why the other mezzanines didn't work that we'll be investigating here. Now that everything is working again we hope to take some data tomorrow.

Kyle spent most of the day working on getting mirror alignment targets ready for eventual mirror installation and alignment on the gondola. Both he and Kate are leaving tomorrow, so he just wanted to tie up some loose ends before going back to MN. I forgot to mention in the last post that that, in addition to the gondola crew, Franky was replaced by Kevin a bit over a week ago, and a postdoc from McGill (also named Kevin, hereby known on the blog as KevinB) arrived yesterday. Kevin and KevinB spent a fair fraction of today setting up a new computer, christened 'hepburn' after the UMN group's recent theme of dead actor/actress computer names (joining monroe, mcqueen, and lamarr), that we bought for bolo streaming/visualization work.


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