The Water Chiller

As Dan mentioned, I had the pleasure of draining the water chiller last week. Few have worked with the water chiller and come away clean. The water pump has as much power as a small lawn mower and can move a gallon of water in 2 seconds up 100 feet, which led to a fantastic disaster scene the first time we tested it in the lab.

For the past couple months we've been refilling the water chiller at about 2 gallons per week. The system is closed, so we were sure there was a leak. We were never able to find it though because you can't open the access panel with the exposed 1.5HP finger eating fan running inside.

Once it was open for draining, I toggled the manual bypass valve to try to get some of the last liquid out of the maze of pipes inside, and found this gem:


The manual bypass valve has a 1" long 1/16"wide crack running down the length of the body, which vomits a vile mixture of antifreeze and fungus water when toggled.

The other user accessible valve I needed, naturally, is also broken:
This valve shuts off the flow to the water pump, so that you can disconnect the device you're cooling water for. It now only closes to the point of the chiller drooling like an old dog.

Almost there

Since we stopped observation on August 22nd we've been reversing our work of the past year, taking pieces off the telescope and putting our gear back into boxes. It turns to be easier to take things apart than to put them together: in under two weeks we've gone from a fully operating instrument to a bare telescope with only mirrors and servos still attached. While Dave and I have been crawling all over the telescope, Ian and Tom have been going through the storage container, packing boxes and making sense of all the junk we've accumulated. Bryan was trying to work on data analysis so we made him drain the water and antifreeze from the chiller into jugs. Today we took apart the gantry, which was the last structure we're going to take apart ourselves.

To remove the various panels we had the telescope in birdbath position for a few days, and an overnight rain left this tree stump pattern on the primary. The Vertex guys are showing up in a little more than a week to handle the dis-assembly of the major pieces with the big crane as well as final preparations for shipping. We're in good shape for their arrival so we're taking a few days off this weekend.

HTT at JAO dedication

On Sunday, July 11th, nineteen members of Huan's family came out to the site for an official dedication of the Huan Tran Telescope at the James Ax Observatory. In their presence, we installed a plaque commemorating the project's namesake scientists.

Unwelcome Visitor

I almost stepped on a rattlesnake sunning himself next to our storage container. He then decided to hide under the container and we thought it wasn't a good idea to leave him there. Fortunately Bill knew exactly what to do:

Observations

Things are winding down in the field a bit - tomorrow we'll be briefly down to 5 people for a few hours between Aubra leaving and Hans arriving. The receiver, telescope and readout are behaving well enough now to keep things running with only a few people. We've already achieved many of the instrument demonstrating astronomical observations we planned to in California, including:

• Jupiter - the brightest point source in the sky at 150GHz, for mapping our beams and calibrating throughput
• Tau A, the crab nebula - A bright polarized source in the sky, for demonstrating and calibrating polarization sensitivity. Humans saw the supernova progenitor 1000 years ago.
  
• The Galaxy - We're observing this one the same way we'll observe the cosmic microwave background, but it's much brighter, so it has a fast turnaround time and acts as a dry run for science.
• Saturn, Mars, 3C279, J1229+0203, etc - An assortment of sources across the sky, planets and the brighter quasars, whose positions have been measured to exquisite precision using optical telescopes and interferometer arrays like CARMA. We measure where they appear to be in our telescope, and check that against where we know they actually are.
  

It's an exciting time to be analyzing data for Polarbear.

Hair cut

The moon is waxing gibbous again, which means the Polarbear receiver and I have been out in the field for nearly 2 months, and it's time for a hair cut. Thanks to Kam for picking up the shears in Bishop, and Dave for cleaning up the back and tolerating the mess I made of the bathroom.

Automated operation

The Polarbear receiver with operating bolometers ran continuously as the HTT scanned the sky all night last night. We all left it to get some sleep, but as of dawn, all systems appear to be working. As you can see from the dawn photograph, the weather was imperfect by morning. We'll have to look at the data to see how opaque the atmosphere was during the night. Jupiter will rise above an elevation angle of 20 degrees in 5 minutes, and the telescope will start observing it as soon as it does

Days 17-19, First Light!

Polarbear at HTT ready for observations

Preparing for observations

The bolometers react to elevation changes!

And there was much rejoicing.

Ready for planet observations in the daytime

Looking for Mars....

There it is!

A celebratory cup of noodles

The next day: Jupiter!

Ian and Nate working on scans

The traditional first light Apple Strudel

Days 12-16, Cooldown

The aftermath of assembling and

installing the receiver. Where's the broom?

Ziggy assembling the readout crate

Ian arrived along with Nate from UCSD

Chase and his stylish hat

Peter and Marius finished weatherproofing the electronics crate.

Mike and Steve from OVRO help reinstall the electronics

crate.

Ziggy getting his manlift driver's license

Dave working on measuring optics alignment

with a theodolite

Preparing the telescope for observations

Dave and Adrian preparing for optics alignment measurements

from inside the telescope.

Measuring the position of the primary mirror

Ziggy and Marius install the readout electronics inside

the electronics crate.

Second Week: Receiver Assembly

Mono Lake from route 395

Paul arrived, and got to work implementing his front

mounted ladder which is anchored at the ground

and attaches to the telescope to get into the boom area.

Look, ma, no hands!

Dave got his his turn at ringing the bell.

Close, but no cigar.

Takayuki arrived and here he is working

on the receiver.

Wrestling the radiation shields in.

Kam , Paul, Daniel, and Dave installing safety rails and floor into

the telescope.

Dave working on the receiver hoist hardware.

Installing the radiation shields onto the

receiver.

The receiver just fits through (after

you remove the door).

In a few years, everyone will be

doing the hardhat-suspenders-booties-latex

gloves-unshaven look. You saw it here

first.

Nothing like a new fresh sticky mat

Kam driving the manlift. Take note his birthday will

be coming up sooner than you think. But where to park

it in Berkeley...

Peter arrived this week and is working on receiver

assembly here.

Another Peter action shot. He can swing a mean allen key.

Peter and Ziggy putting on the 50 K

radiation shields.

Bryan and Takayuki testing the pulse tube cooler before installation.

Bryan working on the pulse tube cooler.

Daniel, Peter, and Marius weatherproofing the electronics

boxes.

We had some problems getting the water chiller for the

pulse tube compressor to work. Tony came by and

installed a fan regulator and recharged the compressor.

Much better!

Chase running ethernet through the cable wrap.

Takayuki installing cables in the azimuth cable wrap.

Dave and Marius installing the receiver hoist.

There are eleven of us here now. Many parallel projects

on the telescope and receiver.

Paul brought his own Skilsaw

Half-wave plate rotator

Removing a press fit pin that is in the way.

finally!

Kam and Dave working on safety rail installation. After

some cold windy weather and some snow, we're having

a period of warm still weather.

Kam and Dave enjoy the view from the telescope

Nils bought a theodolite to align

the mirrors and receiver. It measures

angles to 5 arc seconds. Peter trys it out.

Paul and Dave Woody

Paul working on a pipe for the safety rail

Paul shows off the safety rail

Peter working on the electronics boxes

Ziggy starting the pulse tube cooler installation in the receiver.

Takayuki gets the pulse tube cooler

ready.

A late night effort from Ziggy, Takayuki,

and Bryan and the dewar is closed and

pumping.