This past two weeks have been eventful. Most of the prior week was spent trying to get the VIRUS enclosures and cryogenic safety systems online for the first delivery of liquid nitrogen into our big tank. This involved installing lots of cryogenic lines and one large LN2 tank on each of the VIRUS enclosures.
Although a few last minute alterations had to be made, the filling of the tank went smoothly. A single truck can not fill our tank but we did put in 4,000 gallons of LN2 into it. Much of this liquid would be burned off quickly to cool the tank and all of the cryogenic lines that lie between the tank and the VIRUS enclosures. Just for reference the cost of very pure LN2 trucked out to W. Texas is about a dollar a gallon.
The contractors for the tank and cryo-lines lead a safety class for the staff and we reviewed all of the alarm and oxygen sensors now placed around the facility.
The mirror team continues to swap freshly coated mirrors for the mirrors with the oldest coatings. This past week they swapped 4 mirrors.
We have installed an in-line filter for the fan venting the CCAS tower. This filter will allow us to reverse the fan and run it continuously during the day to keep the tower close to ambient temperature. The software group has finished a prototype piece of code that will turn off the fan just after sunset or if the weather conditions indicate a “close all domes” condition such as high humidity or dust.
The wide field corrector is undergoing extensive “at angle” testing to make sure that the alignment can be maintained between the assembly and shipping vertical axis and the 55 degree angle that it will live at in the tracker. These tests are being done at University of Arizona. When done the corrector will be put into a special shipping box and sent to W. Texas on a special air-ride truck.
Happy New Year! The blogger is back from Winter break and travels to January Science meetings.
We will start with the bad news. The tests on the corrector have determined that there is significant asymmetries. These are asymmetries beyond what were found and reported to the board of directors in the December meeting. Those aberrations were going to be removed by changing the plate glass that was going in to seal the bottom of the corrector into a fifth optical element with some small power. That optic has been fabricated and installed in the corrector. The newly discovered astigmatism was found off axis and might have an impact on image quality at the edge of the field of view. To further investigate this optical issue we are adding a few months to the delivery date of the corrector. Instead of being delivered in late January the new delivery date is expected to be early May and significant on-sky commissioning during the rainy season perhaps pushing us into September.
On a more positive note the 2nd VIRUS enclosure has arrived and installed.
Panoramic views showing the VIRUS Enclosures being installed. The top shows a view from in-front of the mirror and the bottom shows a view from behind the mirror. Both are taken from the catwalk.
There is a lot of plumbing and electrical work required to finish the installation. This is our highest priority.
During the long break the Remote Thermal Area contractors have installed the glycol chiller and are in the process of commissioning it with glycol. This nearly completes the Remote Thermal Area project. Only a few punch list items remain.
The HPF doors also arrived and have been installed. The HPF is now thermally isolated from the spectrograph room. The Penn State Team will monitor the temperatures inside and outside of their enclosure to see if our new Mitsubishi units can hold the temperature to a tight enough tolerance for their specifications. Meanwhile the insulating panels for the HRS II have arrived and will be installed in the coming month. These panels along with an active feed back heater inside the enclosure should allow the HRS II to be held to extremely tight tolerances, < 0.1 C.
The mirror team has started mirror swaps and started using the Strip and Wash room to remove old mirror coatings and prep them for the coating chamber. Our goal is to get the team up to 4 mirrors swaps every 3 weeks.