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.

Day eleven: Mounting the Receiver

The receiver was lifted into the telescope and attached saturday

Ziggy and Bryan leak checking the receiver

The dummy receiver and hoisting system.

The A-frame holds an I-beam with trolleys

and chain hoists.

Takayuki and Dave hoisting the dummy

receiver.

Bryan and Ziggy use a coordinate-measuring machine

to measure the relation of the focal plane to tooling balls

on the outside of the cryostat.

The receiver ready for its trip to the telescope.

Adrian drives the receiver over.

Backing into the telescope area

Almost there

Rolling the receiver off the trailer.

Swing your partner, do-si-do

And under the hoist.

Pondering the rigging

Load straps and engine levelers.

Reference tooling balls on the front of the cryostat

Rigging continues

Paul shows off his safety rail

Marius mans the tag line

Peter watching the clearance on the back

Final checks

Ready for launch

And we have liftoff

Ziggy shows his double chain style

Bryan and Dave watching at the top

Bryan and Peter putting in bolts

Dave and takayuki on the other side.

Paul works on the front side of the temporary weather shield

Turbo pump on, Ziggy watching the pressure

Attaching the pulse tube cooler

Sun dropping to the horizon

Bryan, Ziggy, and Dave on the boom

Receiver in position

Hooking up the cryogenic monitoring

temporarily on the ground.

Bryan and Ziggy get the temperature logging working

Everyone watches the starting of the pulse tube cooler

We're cooling

The hoisting crew, paul, dave, peter, ziggy, Bryan, Marius, and Takayuki

Adrian swapped in for Peter.

A celebratory drink.