ATA Trip Report July 7 2011
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ATA Trip Report July 6,7, 2011
Jrseti 09:42, 7 July 2011 (PDT)
July 6, 2011
Jrseti and Dr. Gerry Harp traveled to the ATA this week.
As you may know, the ATA is still in hibernation. You would think you could turn everything off and all would be OK till the next time you need to perform observations. Not true! It is not good for such a system to be idle for an extended period of time. There are several issues that arise with prolonged idleness:
- The ion pumps that are used to cool the antenna electronics at each antenna need to be kept on and cooled to around 62 degrees Kelvin. Sometimes there are small leaks, or power outages require the pumps to be recharged.
- The motors that move the antennas need to be exercised to keep the lubricating oil in the gears.
- Various things can wear and break.
There are other reasons for sure. The upshot is that the array needs to be babied a bit to keep it in prime condition. That is why Gerry and I are here and will be here more till the ATA comes out of hibernation (which will be soon!). We are also brushing up on our operational knowledge of the array so we can become 2 of the main operators of the site.
This is the first week of really hot weather in Northern California. Last week there were 2 days where it was cold and rainy, which is very strange weather for this area. This week it started getting really hot. 94°F (34.5°C) degrees yesterday. The sun beats down hard on the antennas and they get really hot.
There are 2 main types of cooling at the antennas. The array of 42 antennas is divided into 5 nodes, or groups. Each node has a "Node House" that provides electricity, network communication, and forced air cooling to the antennas. The forced air gets hot during the summer days, as well as the antennas, so we checked that airflow was working well.
The second cooling issue is the ion pump that cools the dewar. Some of these dewars were warmer than they should have been. Last week the temperatures were OK on these antennas, so we think the issue was the severe shift in temperatures.
We climbed up into these antennas and recharged the ion pumps.
This is the view that you see when you climb up to work on the antenna.
To charge the ion pumps we used a device called a "Model 360518 ION PUMP CONTROLLER" made by HeatWave Labs, Inc.
I would climb up to the top back of the antenna, remove the top of the controller box, and plug this unit in. Then wait.
That was my fun day!
I was able to take some nice pictures at sundown. Hope you enjoy these (sorry, taken with my old iPhone)
Today we turned on the equipment in the SPR (Signal Processing Room). That went well, but we slowly went through all the instructions to make sure we turned everything on correctly.
There are 2 tricky parts to turning everything on. Finding all the power switches is confusing, sometime I'll have to document that properly. Also, the adjustment of the FSCK (Fast Clock) is tricky. But we got it all to come up.
The F Board of the C correlator would not report a temperature, so we pressed the reset button. It came up.
We also had to restart all the JSDA processes on auxcntl. The set-defaults.csh script reported errors otherwise.
I tried recharging the ion pump of 4f. It seems to have worked. We are waiting for the cryo temp to go down on 4f. Here's hoping!
Gerry is running the delay cals. Jrseti 15:57, 7 July 2011 (PDT)
Antenna 4f did not cool all the way down :( It only got down to 107 degrees K. Bummer.Jrseti 18:05, 7 July 2011 (PDT)
Gerry made a lot of progress on the delay cals. Jrseti 18:05, 7 July 2011 (PDT)