The week of March 23

We did some simulations of data transfer rates in preparation for VIRUS coming on line. The data set consists of 900 fits files; each file is 8524800 bytes in size. The working assumption is that one Hetdex image consists of 150 spectrographs x 2 amplifiers/spectrograph x 3 dither per field with a CCD size of 1032×2064 pixels. Total data size is 7,672,320,000 bytes (7.3 GB). The data would be collected over 20 minutes (~6 minutes per dither) but it only took 449.5 seconds (7.5 minutes) to transfer this data to Austin. Thus we should be able to keep up with the data collection rate without bringing the network to a crawl.

The large air and glycol (“Blue Thunder”) hoses were installed through the Az wrap and laid in the trench in the floor and through one of the ports through the pier to the ring wall in the last two weeks. The next step will be to connect these to the outside lines and do a pressure test of the system.

All power connections for the VIRUS enclosures are now complete and tested. We have also conducted some heat load tests on the liquid nitrogen system by placing plastic bags over each of the VIRUS bayonets (the component that will stick into a VIRUS unit to keep it cold). So far most of the system checks out close to specification.

The primary mirror group installed 4 mirrors this week and continue to keep up their 30% over expected swap rate in hopes of being close to completion when the corrector is ready for commissioning.

The CCAS shutter failed this week and could not be repaired from inside the CCAS Dome. Instead of having to rent a very expensive 90 ft manlift the mechanical team found a way to safely undo the mounting to the CCAS Dome and lower it to the ground. A replacement shutter is on order and should arrive in the next week or two. It will be installed by just reversing the procedure developed to remove the old shutter. Until then we’ve installed a simple wood plug that can be removed manually (after climbing the 90ft tower) to continue with critical primary mirror work.

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