Mountain Polarbear

The Water Chiller

2010-09-06T18:56:00.000-07:00

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

2010-09-04T16:31:00.000-07:00

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

2010-07-20T21:33:00.000-07:00

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

2010-06-10T10:41:00.000-07:00

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

2010-05-26T22:17:00.000-07:00

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

2010-05-21T23:23:00.000-07:00

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

2010-04-27T05:58:00.000-07:00

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!

2010-04-18T18:04:00.000-07:00

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

2010-04-18T17:31:00.000-07:00

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

2010-04-12T11:44:00.000-07:00

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.

Second Week: Receiver Assembly

2010-04-10T10:07:00.000-07:00

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.

Receiver assembly, the first few days

2010-04-03T23:00:00.000-07:00

We rented a trailer to move the receiver to and from the telescope,

and also to provide some more room for assembly .

We ordered a gantry crane to help with assembly of the

receiver, but it hasn't come yet, so we had to improvise

with the manlift.

Make sure that rigging is good....

suspended.

And into the receiver cart

And finally into the container

Ziggy gets the 240 mK 3He refrigerator

ready for installation.

Starting point for assembling the receiver

Dave explores how high we can go in the manlift.

Daniel working in our internet cafe that is disguised

as a tent.

Ziggy and the receiver showing the focal plane supports

Installing the water chiller for the pulse-tube

compressor.

Sunrise over the Owens Valley Radio Observatory site

The Sierra Nevada

Breakfast at the valley site

Kam and Chase cooking everyone a scramble

Kam, Bryan, and Dave working on the

telescope

Pulse tube passes pre-installation test

Bryan is king of all he surveys...

Dave working in the telescope

Kam assembling the focal plane in some stylish

headgear.

Ziggy working on the receiver

First Day Unpacking Cryostat

2010-04-02T22:35:00.000-07:00

The receiver and electronics have been brought

to Cedar Flat, CA for a test run on the Huan Tran Telescope (HTT).

We'll be here for a few months testing the entire

system integrated together for the first time.

Here's a picture of the truck driving up to Cedar Flat

Boxes coming off the truck. The motorized tailgate

made things a lot easier.

The cryostat is big enough that it needed two boxes.

Double wood boxes with foam between them.

Moving the boxes with forklift. A nice

view of the HTT.

Mike from the CARMA staff lifting the compressor

for the pulse tube cooler into our "utility" container

which has the compressor, water chiller, and telescope

servo systems. We'll move this container to Chile with

all the systems installed.

The focal-plane end of the receiver arriving at the main

container.

Chase, Hans, Dave, Mike, Bryan, Ziggy, Kam, and Daniel.

The whole crew with Adrian added.

Then, it started to snow. Ziggy and Bryan are assembling

the receiver cart.

Inside the main container finishing

the receiver cart. When moved to

Chile this container will have oxygen

enrichment. It's the only heated

container.

Ziggy gives us his goofy thumbs up

since the receiver seems to have made

it in good shape.

In Memorium: Huan Tran (1974-2009)

2010-04-02T16:59:00.000-07:00

In December 2009, the POLARBEAR project manager Huan Tran

died in an tragic domestic accident while on a trip to work on the

telescope.

We are all greatly saddened. We lost a great leader, scientist, and

friend. Huan was involved in every design aspect of the experiment

and was deeply dedicated to the project.

The telescope has now been renamed the Huan Tran Telescope (HTT)

in his honor.

We miss him greatly.

Polarbear Telescope Assembly is FINISHED

2009-09-07T17:01:00.000-07:00

Brian and I left the site this weekend, so I am officially declaring the assembly phase done. There are many things left to be done, but I have been away from Berkeley too long, so I decided to come back.

Although it took about twice as long as I originally thought it would, the structure is basically where is should be. We have some major outstanding issues, like the servo and the enclosures, but those will hopefully get done in next few months. Expect to come back here in about a month.

I took this picture above just as the sun was setting. You can see that the pad is a bit more tidy. Brian was busy trying to pack up, so I couldn't get him to pose next to the telescope.

Thanks to the GD guys for sticking with it until the job was done. I am VERY excited that Polarbear finally has a telescope- it has been 6 years in the making for me. I was just told that we are celebrating 400 years of the telescope. Here's to hoping that Polarbear has as much impact as Galileo!

Painting the box

2009-09-07T16:53:00.001-07:00

I spent the last few days painting this box. It is a lot harder than you might think. David convinced me to paint the box so that it would keep over the winter, and it could save us a lot of money.

It was hard because there are so many corners on the outside. Also, low grade plywood sucks up a lot of primer. It took 3 gallons of Primer and one gallon of overcoat. The roof is also not strong enough to support a person, so I had to use the lift to paint up there. Brian was using the manlift during the day to paint the telescope, so I was using it in the dark in the middle of the night.

There are a few more boxes to paint, but I have decided that next time, I will use a paint sprayer. Latex paint requires a special airless High pressure sprayer, which is why I did not get one right away, but I arm hurts way to much now to do this again.

Scorpion

2009-09-07T16:49:00.000-07:00

I found this guy in front of the utility container in the middle of the night. I put it in bag, and brought it down to my cottage and forgot it there. I hope the bag will keep him for the next month.

Some of us have been changing out shoes at the high site, and this photo is supposed to convince you that it might be a bad idea.

Repainting the Structure

2009-09-07T16:41:00.001-07:00

Brian has spent the last few days repainting the entire structure. It took 5 gallons of paint, and we only have about a quart left for touch ups. The original plan was to just touch up the structure, but it made it look too uneven, so we decided to go all way. We will see how nice it looks in 6 mo after we have had our grubby hands all over it.

This was some special two part epoxy paint-Interthane 990HS. I hear that it cost a lot of money, and it smelled really awesome.

Elevation motor counterbalance

2009-08-31T10:35:00.000-07:00

After a suggestion from Eric, Brian came up with a counterbalance to the elevation motor. There is a spring now that is mounted to the bracket that holds the motor and the gear reducer, and is in turn connected to small friction wheel. The whole assembly is in the middle of getting painted, so try to ignore the gray primer.

The idea is to keep the two friction wheels aligned properly, and to prevent uneven wear on the wheels, something that we noticed on the BIMA wheel.

The hard part is to try to figure out how much compression should be on the spring. I ordered some heavy duty pressure indicating film to figure this out, and I intend to send it through the roller. Stay tuned for the results.

You can also see the rain guard that Brian rolled from Aluminum. It fits very well.

The perfect polarbear picture

2009-08-31T02:47:00.000-07:00

Well, not really the best, but I wanted you to get a sense for why I think it is so hard to get the perfect polarbear telescope picture.

First- here are some reasons that now is a bad time to get a picture:
1. The sky is too clear.
2. The pad is a mess
3. I am the only one here, so there are no people to pose for scale.
4. I need some more equipment.
5. The elevation does not work again, so I cannot get the perfect angle.

Here are a series of 4 photos, all taken on the same night, all within about 2 hours, and all taken from the manlift. It is surprisingly difficult to hold a camera way up there.

This first photo is taken just before sunset, while the telescope is totally in sunlight. I don't like it because the sky is boring, the light is harsh, and the shadow on the trees is very dark. Taking a photo of a large white object also throws off the exposure.

This next one was taken as the Sun was below the trees. It is okay, but the horizon is all skewed.

This next one was with the sun even lower below the horizon. I think this is my favorite, and that is why it looks more processed. The sky is becoming more interesting, and I got he position of the manlift right. The color is not textbook, but I never like perfectly corrected color. One big problem though is that it is much darker than it looks, so the camera had to be pushed to higher sensitivity, and the sharpness is just marginal because of camera shake.

This last photo was taken just before the sunset. I left the white balance set for daylight, just so you can see how weird the color gets up there. The light was so low that none of the photos were usable due to camera shake. I want to try out a camera clamp to see if I can push the exposure longer.

We dont have long before we lose the manlift- just a few more weeks, then it will be much harder to get this shot. I am waiting for a night that is more interesting, with lots of clouds and almost raining.

some more critters

2009-08-31T02:33:00.001-07:00

This family of odd birds was spotted at the high site. They are often seen avoiding your car on the way up to the site. I hear that they make good hunting. The are called Chuckers, and look like some variant of quail.

I have no idea what this is, but I left the door open on the container for a short time and he made it in. I hope it does not bite, but he was plenty angry when I trapped him in a plastic cup.

Servo Selloff

2009-08-20T23:20:00.000-07:00

These last few days have been all about getting Track beam mode to work. Basically, it was Nate making and running a scan, Brian analyzing the data, and the Richardson guys changing something, then repeat. We were not able to fix the problem, but we have some ideas, so I will come back in a few weeks to try out the solution.

So we decided to do a conditional sell-off, one where we check out everything except for Track beam mode. Brian #3 came today to witness. We did turn out some minor errors that were fixed, and we did end up signing the document. Bryan #2 was the third witness.

Next week, I come back to finish up some loose things, and support Brian #1 while he paints the telescope.

I am way behind in posting photos, so here comes a random selection from the last couple of weeks.

We took this photo of Adrian about 1/2 hour after Track beam mode started working, essentially making Polarbear a whole telescope. We had about 5 minutes before sunset.

Nathan spent a lot of the time looking just like this. Staring intensely at the computer, spitting out lots of scan.

As you can imagine, the manlift is pretty fun. Both Adrian and Bryan now know how to drive the thing.

There was a crazy dust devil that hit the CARMA array, apparently, it happens a lot.

We sent Adrian into the big hole to do the last cutting of the tabs. The cable wrap currently works, but we will watch it closely.

I think that Adrian liked it in there. Dave and Daniel scoff because this hole is luxurious compared the the hole they had to sit in for 5 hours.

Brian #1 had to rescue Adrian, I think. Otherwise, I am not sure what he is doing.

Hans really got into priming the counterweights, but Brian #1 put us both to shame when he started using the correct roller.

And finally, the man of the hour, Radek and his family came for a visit. He was impressed.

Track beam mode

2009-08-19T14:14:00.000-07:00

Barry, a software guy from Richardson, spent all Tuesday fixing track beam mode. It now works, and we've begun testing scans. We started with some fast circle scans:

The first tests showed 3 arcminute peak error in elevation and about 1 arcminute in azimuth. Sean remembered that the servos were set back to default for that, so he retuned the position loops back up to 0.5Hz and we repeated the test. Elevation and azimuth both came down to about 1 arcminute.

Next we started looking for excitation of resonances. On turnarounds, where velocity goes to zero, we often see resonances at 2-5Hz; the frequency doesn't seem stable. We also see some of the lines we saw in the accelerometer out at 20 and 40Hz. To simplify the problem we switched to purely azimuth or elevation scans, and saw a little bit of coupling between az and el - the servo which isn't being driven sees a wobble of about 0.01 arcmin peak.

At this point we noticed something really strange - a glitch in the encoders. For one sample, the rror jumped by about 1.5 arcminutes, which is mechanically unlikely. In the raw data coming back from the ACU, it looks like the old encoder value held over one sample. The ACU sequence ID, which counts the 100Hz clock which synchronizes all of our readout, increases correctly, so the software buffers are behaving. Later, in another chunk of data, we saw a big string of these glitches:
This plot is sinusoidal scan in elevation at fixed azimuth. From 50s to 150s, the drive appears to behave correctly: peak error of 1 arcminute and a small spike where velocity goes to zero, maybe from momentary static friction. At 150s, the behavior changes dramatically. The values from the encoder appears to occasionally fall behind for 1 sample and then catch up. After a few more seconds it falls behind by 1 sample for a duration of several samples. After 25s it's permanently locked into falling behind and contributes an error proportional to the elevation velocity.

Observation scan

2009-08-17T13:17:00.000-07:00

20 degrees, 4 degrees / second, 2 degrees / second / second

Balancing the Telescope

2009-08-17T13:03:00.000-07:00

Last week, we worked on balancing the telescope around the elevation axis. The telescope was heavy toward the boom and toward the primary mirror, so weight was added to the lower back. 250 and 400 lb steel plates were added. The torque required to move the elevation was reduced, and is likely now in an acceptable range. We need a better scale for our static testing

Servo tuning

2009-08-17T12:45:00.000-07:00

After Al and Brian fixed the El drive alignment they handed Polarbear off to Sean for servo verification and tuning. Polarbear has 3 distinct servo loops. GCP sends position commands to a position loop, which sends velocity commands to a velocity loop, which sends current commands to a current loop. The current controller is factory autotuned once it's hooked up to the motors, but the velocity and position loops must be hand tuned.

To tune and verify each servo Sean repeated two basic tests: network analysis and impulse response, looking for the same things we do in bolometers - bandwidth, resonances, time constants, etc. He runs the tests largely by hand - turning the knob on a function generator over 30 seconds or so.

In their servo system, we have some margin to play. As long as we remain stable, we can trade between overshoot/settling time and bandwidth. Since we want to do fast scans with out needing much pointing precision, Sean cranked up the position loop bandwidth from .22Hz to .5Hz - the spec is .25Hz.

The velocity response of our telescope has a resonance at 3Hz due to elasticity in the drive train:

This sweep goes from .1Hz to about 15Hz. The measured velocity not coming up to command velocity on one side is due to a problem with the DAQ that acquired the data. At 3Hz the measured velocity phase slips about 90 degrees behind the command.

Elevation drive alignment

2009-08-17T12:07:00.001-07:00

After adding 1000lb of counterweight we ran a balance test using the scale. We measure the force to hold the telescope still at several elevations. While driving the elevation between two positions someone noticed that the El drive was walking far enough off to drag the drive mount into the side of the primary friction wheel. This must have been happening for awhile, because the paint is scratched off all along that side.

The azimuth drive avoids this problem by holding the wheel in place with a pair of jack screws above and below the tensioner.

Al and Brian were able to adapt that to the El drive. In a day they had welded up new brackets and punched holes into the back of the boom to mount them. We've run the elevation quite a bit since then and the alignment is holding steady.

We went up onto one of the BIMA platforms while they were shutdown for generator maintenance to check out their drive, which ours is modeled after. Huan noticed that the two jack screws touch the same plate, so that they are very close together, while ours are fairly far apart. That constrains the wheel from turning, which could cause long term problems.

We're going to try pressure sensitive tape to check uniformity of the contact, then we'll see if the system needs improvement

BBQ

2009-08-17T11:52:00.000-07:00

The CARMA observers invited us to barbecue Saturday night at the high site. it's quiet during the weekend so there were only 7 of us: Adrian, Huan, Nate, me, the 2 observers and a visiting friend of theirs. They have a gas grill, so the turn around time between working and cooking is fast.

Adrian periodically basted the ribs with barbecue sauce, and the observers had some fresh vegetables. Their friend is from Indiana, so he had very precise instructions for grilling corn on the cob.

Unlikely Visitor

2009-08-10T09:24:00.000-07:00

I was at the telescope late one afternoon when I heard a big thud on the utility container. I was not expecting to see a seagull out here in the middle of the desert mountains. The last thing I want out here is a flock of seagulls, they are the rats of the air, but I do not think that we are in any danger of that.

Secondary Adjuster and cable wrap

2009-08-10T09:17:00.000-07:00

All the parts for the secondary adjuster finally arrived, and Brian's contraption is done. It is hard to tell from this picture, but he replaced an unbalanced jack screw with this threaded rod that is not welded into the structure. There is also a 3/4 plate that is attached to the stainless box. Together, these form a push-pull mechanism that should make it easier to adjust the secondary.

I am afraid, however, to test it since we have photogrammetry for where the secondary is right now. I will have to come up with a way to measure it's current position before we tweak it.

Also, when I was slewing around the AZ, I found this other failure mode of the cable wrap. It turns out that the ends of the 'U' can touch each other, and sometimes when they do, the tabs on the outside catch. Al and Dave had previously cut off the ends on the inside, so when the 'U' collapses, the tabs no longer catch. I am wishing that Dave was here, so I cold send him into the hole to deal with this. It will probably take 1.5 days to get this done.

Air conditioner saga

2009-08-10T09:05:00.000-07:00

I initially did not have an air conditioner on our container because the Japanese in Chile warned me from getting an american unit that cannot be serviced in Chile. I also hoped that we could 'get by' but this summer has proven to be a scorcher, and so began the air conditioning saga.

I started with this lousy 8000 BTU unit that I stuck in the vent opening. This thing was only psychologically effective, the temperature did not go down inside at all.

Unit #2 was supposed to be a 14,000 BTU portable unit. After the unit was late by 1 week, I started calling the shipper every 3 hours, and finally decided that Yellow Freight had lost the shipment somewhere in LA. Amazon did finally refund our money.

Unit #3 was an emergency acquisition from Kmart, another 8000 BTU unit, which worked only if you were in line-of-sight. The container is so air tight, that it also caused a serious vacuum in the container, so every time you opened the door, your ears would pop.

And finally, I just in stalled this a couple of days ago, what I should have done 6 months ago, a split, ductless, R410a system. It is actually not that expensive if you install it yourself. It is 24,000 BTU, runs on 208V 60Hz, and is surprisingly quiet, because the compressor is outside.

I installed it just in time for it to get fridgid here, so I haven't really been able to test it in 100 degree weather.

If I installed the refrigeration lines with a leak, then it is legal for me to top off the system with R410a, a non CFC based refrigerant. The only problem is that if we want to run this unit in Chile, we will need a 60-50 Hz frequency converter. I think we might already need one for the water chiller anyway.

New car

2009-08-10T09:03:00.001-07:00

Brian traded in his awesome WRX for a brand new WRX STI. If there is any car made for this area, this is it.

I took this photo to make Daniel feel inadequate because he also has a non-STI Subaru, but really, it just makes me feel inadequate to be driving my POS rental.

counterweights and controller

2009-08-08T09:49:00.000-07:00

It has been a week since the last post, so here are some of the things that went on.

First, Brian and I are currently the only people here. There are plenty of ethernet connections now.

Brian and I did a measurement of the imbalance with a heavy duty hydraulic scale. We where able to determine that there are 9000 ft-lbs of imbalance, with the CG toward the shields. It turns out that this measurement comes very close to the measurement from the motor current that Sean came up with. I was hoping for better. I think the reason we are off is because of the baffling, it was just heavier that I estimated.

This imbalance is bad for a couple of reasons. First, I talked to the designer of these drives, and he definitely thought that the friction wheel was not designed to hold that kind of imbalance. Secondly, if the system where to fail, it would end up with the boom down, so not very safe.

To fix the counterweight problem, Brian and I decided to go with Steel. This is after we scambled around looking for lead or other solutions. The OVRO staff told us to go with a welder in Bishop, and they will, source, cut, and deliver our counterweights for $2 a pound, which is not bad. The couterweights will show up on Tuesday, then we have to paint them, and then on Thursday we are having a boom truck come out here to install them. This should get us within a few hundred pounds of balance, and then we can add trim weights.

A second problem that developed has to do with the servo. I think that I burned a chip on the AZ motor controller. Mike sent me an accelerometer so that I could look for resconances in the structure. I was slewing the telescope 360 degrees in 90 seconds, then stopping and turning around. After looking at the accerometer data and trying again, I foind that the Baldor controller was complaing of a low DC bus voltage. These things are suppossed to protect themselves from events like this, so I am not sure how this happenned. After talking with Sean, he decided to get a new unit, and will bring it next week. Until then, we have to move the AZ the old fashioned way, by pushing.

Track beam problems

2009-08-01T01:00:00.001-07:00

Sean came from Richardson TX about ten days ago to start testing out the servo. After some quick initial success, we began to find some problems. The first problem was a velocity limit in el, fixed by reprogramming the motor controllers. The next problem was an oscillation in the position loop in Azimuth. After a couple of days of back and forth with Richardson, they were able to figure out that it was some arcane software lock, which was failing to recognize a hard-wired rate limit. The az appears to now go to a position reliably.

The next step is to tune the parameters, but I am not sure we can do that until I am happy with the balance, more investigation is needed.

The current headache is that we cannot get track beam mode working. This has been anticipated, since SPT had some major issues getting it to work. We seem to make tiny bits of progress every day, but it is slow going because the system is so complex. I spent, for instace, some quality time on the floor of the contiainer fine-tuning some resistors so we could get exacly 10 microsecond pulses. Not fun, but it did appear that we got one baby step closer. The telescope is at least following the scans, and we saw for the first time a basline polarbear scan, 15 degrees back and forth.

We are still not getting any replies from the ACU, so event though the telescope is moving, we would not be able to tell where it is moving without looking at it.

Assembly almost done

2009-08-01T00:40:00.000-07:00

The major assembly of the telescope is nearly finished. We have reached the six-week mark, and Albert has left for a week-long trip home. We hope to have everything done in two weeks.

Marius left for home a couple of weeks ago, and was replaced by Nathan, but here is an old photo of Marius painting the saddlebags. He and Dave took a lot of abuse for how they went from space-qualifies looking before the paint job to little rascals clubhouse looking after the paintjob, but the automotive paint will do the job, and it was a pretty smelly and messy job. I still think that Marius has some paint on him somewhere. The saddlebags are now installed, thanks to a very careful layout job from Brian and some help from Mike with the forklift. I am afraid that we will need a taller ladder to reach these saddlebags.

The baffles have been slowly going on for the last couple of weeks. The panels go on like a complicated 3D puzzle, where each piece had to be slightly trimmed to fit. "Tony" got a lot of grief for this job also.

We had one baffle casualty when a dust devil caught a sheet before it was fully attached. The sheet metal was somewhat mangled, but they banged it back into shape and I think it is okay for now. I will request a new one when more baffles are being made.

The last major piece went in a couple of days ago when we finally installed the cryo mass dummy. Al decided to install the frame first, then the ballast weight second. You can just barely see the Pullz-all that we used to hoist things into place. The manlift stood in for the eventual gantry that needs to be made here (80/20 Marius?).

Tony did not get any credit for how everythign fit together on the first try, because Tony did not fabricate these parts.

Here you can see the weights installed. It is a little scary to stand right below these weights, so I dont recommend it.

Here is how the telescope looks now.The look is basically how it will be for the next few months. A few more panels need to fabricated aroud the secondary, and an enclosure the the reciver will need to go on, but it wont look much different.

With the assembly winding down, I am trying to figure out the exit strategy. Of course, the major outstanding item is the servo, more on that later. Brian will be working refining the secondary adjuster of the next week, and I think that we will need substantially more counterweight, we seem to be heavy toward the lower boom, but I am not quite sure yet.

Fire and rainbows

2009-08-01T00:35:00.001-07:00

This is still me playing catch up. There were a couple of days of crazy forrest fires, started by lightning. We could not weld those days. You could see the smoke from pretty far away, even from my Super-8. As it turns out, the fire was on Brian's front door, and he was evacuated. He toughed it out for two days in the campgrounds.

It has rained probably half of the days during the six weeks we have been here. The Cedar Flat site has only been operational for a few years, and they have never seen anything like it. They are blaming it on El Nino. We caught this impressive double rainbow over Polarbear late one afternoon.

Photo catch up

2009-08-01T00:20:00.001-07:00

This is a catch up post showing some photos during the week of photogrammetry. It feels like ancient history now, so much has happened since then, but here goes.

Brian was in charge of placing most of the targets. Not too close, and every shot needs at least 3 'coded' targets to situate the photo. The rest of the spots are the actual targets. The first round also needs an "iron cross" to define the inital coordinates, and scale bars to define the scale. The process is somewhat magical, but if you think about it hard enough, it makes sense. The whole setup costs ~$200K and requires a significant amount of training to get it perfect, but they claim better that 0.001" accuracy.

There is a photogrammetry rhythm that is followed every night. It starts with making adjustments to the secondary, then waiting until the telescope thermalizes, then riding around in the manlift and taking abotu 100 shots over about 270 degress around the telescope. Here's a photo as the sun is sinking far below the horizon. Jay is messing with something, and Brian is adjusting some panels before we start.

We foolishly operated with the doors open most of the time, to keep things cool. Marius's fly traps have been redeemed, and there is a now a disgusting rogues gallery of bugs stuck to one of the traps. The liquid trap is still empty.

At least one night was actually clear enough to see starts. Most nights were cloudy and rainy.

This is an early photo of the targets. By the end, we had many more targets so I could check the warp in the panels.

I saw the sunrise on many occations. This will probably be the first out of hundreds, so get ready.

Polarbear dance moves

2009-07-25T11:54:00.000-07:00

Hey guys,

I've uploaded a video of Polarbear in action:
http://www.youtube.com/watch?v=WY4SNlla3zk

Still pretty fast, despite the imbalance!

Telescope moves!

2009-07-25T00:44:00.001-07:00

Richardson sent out a person yesterday to start on the servo, and I am happy to report that the telescope is now moving under it's own power. As you can guess, there are some issues. The biggest one is that we can only hit 80% of the spec velocity in elevation. This could be due to a number of things, like imbalance or excess force on the friction drive, but more on that later. I want to get Dave to make a movie with his new camera.

On another note, Nathan showed up also, and Dave is hoping that I will focus on him for comic relief.

Photogrammetry

2009-07-24T22:59:00.000-07:00

I have not posted in a long time because the last week had been grueling. I have been up all night in the dark for about five days, and I think I have finally recovered.

We did photogrammetry, and have had mixed results. The primary still appears okay, although I do not think that our setup is precise enough to see something subtle. The panels have also been aligned, except for one. The measurements were showing that one of the panels was off by 0.08 inches, while the rest were about 10X closer. Al came up with a way to suck down the bad panel, but in the process, he and Brian found that the panel was actually resting on the Primary.

After yanking the panel off, however, it sill looks like Al's contraption will have to be installed after all, a job for tomorrow.

But I am getting ahead of myself, we were hit by a couple of problems, the first was that it rained on almost every night, and we not only lost the time that it was raining, but I am also afraid that the mirror would do weird thermal drifting while drying.

In the end, we were not able to align the secondary. I think the problems were in both the software, and the adjustment mechanism. I think I will work on both, an then we will try again. They cryostat mount is still not here, so it is likely that Jay, the photogrammetry person, will have to come back in a few months to try again.

Pictures will be coming later

Panels and countrerweight

2009-07-16T23:13:00.000-07:00

The old counterweights were lifted into place this morning, and now the telescope is almost balanced. We will not know for sure until the torque is measured again. We are currently waiting on a connector before we can turn on the motors.

We have a resident underneath the telescope. We call him stumpy, for obvious reasons. He comes out and pecks at pebbles, but someday he will get a real bug. There are tons of these little lizards everywhere, and sometimes they will freak you out if you are not expecting it.

Brian worked on the panels for most of the day, and they are basically in the right spot. There is a fifth tab though, and some of these might need to be modified. We wont know if the panels are in the exact right spot until the photogrammetry is done, which should start this weekend.

This is how the telescope was left today, you can see the counterweights in the new location.

Old Photos

2009-07-15T13:24:00.000-07:00

Wow, David gave me some old photos of Pauls lab from back in the day. I wonder who these people are?

New tabs and counterweight

2009-07-15T12:46:00.000-07:00

The internet in the super 8 has been out for the last two days, so I have not updated in quite a while. A lot has happened in the last couple of days.

Here is a photo of the shadow of the panels, right before they were removed. You can see tha the gap is a little bigger on one side. The panels just could n0t be mounted in the correct position, so it meant that the panel tabs on the support needed to be reworked.

It also turns out that Caltrans is doing major road work on 168. Every time we go up and down, we have to wait about 20min for a "pilot" car to lead us around the crew.

Al is also relocating some of the counterweights to balance out the primary. It tuns out that the CG is only 3inches off, but at 30,000lbs, 3 inches means a lot of torque. Here is a monster tap that Al is using to mount the threaded rod into some 3" thick plate .

The panels have all been sadly removed, and they are all sitting in this box.

On Tuesday, the hard work began of drilling and tapping for the counterweights, and welding the new tabs. I had to get a burn permit from the Bureau of Land Management, and we have to keep this awesome backpack super-soaker around to fight fires. Al and Brian are working both ends of the telescope.

Here are the new tabs that have been fabricated.

Drilling through 3" of steel plate leaves a lot of shavings.

All the drilling and tapping is mostly done now, the tabs are all welded on, and Marius is now painting the saddlebags. The Photogrammetry needs to start next week, so we are scrambling to be ready.

Dave's Turn

2009-07-10T23:12:00.000-07:00

Albert and Brian are arriving super early these days, and they were able to check the balance of the telescope before we arrived. San Jose had requested that they do the standard balance test, by measuring the torque required to move the telescope at many different elevations. It turns out that the orientation seen below is the min torque, meaning that the center of mass is right above the elevation axis. The plan is to now add counterweights below the axis, and we are waiting for San Jose to make a recommendation.

There is a minor problem with the elevation cable wrap, it hangs on one of the counterwieght bolts.

Brian was able to rinse away all most of the residue from the recent rain. This photo also shows the current gaps in the panels. We are still waiting for a recommendation on how to deal with the panel hardware interference.

It was Dave's turn to crawl into the hole today to redo the shims. He spent half the time with his legs hanging out of hole, and just like in the cartoons, he kept kicking them around as he was squirming around in the the yoke.

He had to poke his head out once in awhile to let the blood drain.

We re-created the scene in the box for the blog.

Here's how we left the telescope today. It is in sad polarbear orientation, but I am actually happy that our problems are slowly getting resolved.

Star Destroyer

2009-07-10T00:01:00.001-07:00

Marius has finished his magnum opus in 80/20. It is as dangerous as it looks.

The air conditioner just barely works. It was a cool 78 degrees, although I could swear it was 76. The key was to keep two of windows closed, and to turn on the system at noon.

The PDU is basically ready to go, but there are some lingering issues with the telescope. There are three major issues that need to be worked out with San Jose- the Balance, the Cable Wrap, and the Panels. We have to resolve all of these issues before we can move on.

Today Brian and Al, the panel pros, worked on trying to align the panels. Although they were able to eyeball it into place, there are two problems. If you look closely, you can see that the panels holes are not symmetric.

Here you can see that there are some interference issues with rods. We will have to come up with a solution, but we want San Jose to look at it first.

Marius and Dave moved into the container to work on the the last 80/20 part, saddlebag #2.

I think that Dave dreams about 80/20 nutplates now.

In case you were wondering, this is where I was to take that last two pictures. I handed Dave the camera, and he caught this rare photo of me. We really are that dirty.

The funny story for today is that my $15 new coffee maker nearly exploded today. There was a faulty switch that popped when I tried to turn it on. Luckily, the circuit breaker worked, and now I am looking for the right coffee maker.

80/20 madness

2009-07-09T00:32:00.000-07:00

Another long day at the site, Albert basically finished wiring the PDU. I also had a minor dalliance with another telescope, antenna 5 from the SZA. They kindly let us remove one of the skirts to have a look at the cable wrap. Lots of pictures here if you want to look:

sza cable wrap

Here is a view of polarbear as seen from the SZA. It is the tiny telescope off in the distant treeline.

I have decided to take the 80/20 catalog away from Marius. He has taken his designs to the depths of interface depravity.

The alignment of the panels is beginning to converge. Brian worked some oh his magic, and looks like we might be on the right track. More to come tomorrow. This is how we left Polarbear at sunset.

On a final note, I had a failed experiment with an air conditioner.
I installed a 8000 BTU window unit into a pre-existing hole in the Control Container. I think we probably need 4X the power, and we dont have a hole big enough. I will look into a more serious solution, but I am worried that by the time I figure it out, it will be fall.

Marius is very dirty

2009-07-07T22:47:00.001-07:00

Today, the cable were mostly installed into the wrap. The servo cables are basically all there, and the compressor cables are all in. I am waiting on our science cables until after the servo is mostly done. The elevation wrap looks pretty, although we could not test it due to the imbalance.

The Az looks orderly, but it won't work without the banana or other fix mentioned yesterday. The plan is to check out the SZA banana tomorrow.

This is all that is sticking out of the base of the telescope. There is a new trip hazard, thanks to the servo cable conduit.

Funny story for today- Marius and Dave put up their canopy worthy of a Sultan. The plan was to built the 80/20 parts under the tent, but Marius spent just as much time rolling in the dirt.

This is the messiest I have seen anybody so far. He cleaned up nice for dinner, but reports that there is dirt all over his motel room.

Back in at the mountain

2009-07-07T00:23:00.000-07:00

This is Huan, and I am back at Cedar Flat today. Things are very different after one, week, but the telescope basically looks the same. It seems as though Marius and Dave have the keys to the manlift now, and they are the mirror adjustment crew. Unfortunately, they ran into a roadblock because the rods on some of the panels are not long enough. I am happy to see that I am not the only person who likes to wear a harness.

It looks like Albert and Brian came up with a solution to one of the cable wrap problems, the outer table is now flat to ~40 mils. They did it by putting a thin radial slice in the table and using an angle bracket on the bottom to flatten the plate.

I did not believe I would see it, but Albert fits inside the base.

Dave and Marius are installing half of the Az Cable wrap. We got one side of the cable wrap in, but after it got installed, we discovered another problem, one we were warned we would see. The AZ wrap pulls away from the wall. We were hoping that the compressor cables would provide enough spring force to keep the az wrap along the wall, but it was not. The solution on the SZA was to use a "banana", you will just have to imagine how it works. Albert is checking with San Jose to see what they think.

In the meantime, we started worrying about the inbalance of the boom. There was an earliet problem with the elevation wheel slipping, so Al locked the elevation in place, and it has not been moved in a week. To see if we could bring it close, they hung 1500 lbs of counterwieght off the belly, and it got better, but it is still not totally there. Once again, San Jose is thinking about this.

Fauna

2009-06-29T22:40:00.000-07:00

Heading down the mountain today, we turned the corner where the road narrows to one lane and saw a black bear. Dave stopped the car as the bear took off up the hill, and as it turned to look back at us I had time to snap one picture before it trundled off.

2009-06-29T22:17:00.000-07:00

Hey guys,

Here are some pictures from my first day at Cedar Flat.

We spent most of the day cleaning machined surface to get them ready for weather sealing, and trying to rewire the camera at the site.

The day was cut off a bit early when it started to rain fairly hard. Some water pooled into the primary (see the pictures) and left a bit of a residue.

Dave

Last Crane day

2009-06-26T00:04:00.000-07:00

Today was the last day with BZ and the crane. It was a big day, and we finished our goal of installing the mirrors.

The GD guys finished installing the last of the adapters into the junk sockets this morning, and they finally lifted the primary out of the cradle and the box. I cant believe we dont have to sit in that box working overhead anymore.

They lifted the primary at four points, with the ability to tilt the primary once it was in the air, so we could set it down level and reposition the crane.

After all the trouble with the adapters, I expected the primary to not mount at all. It did take a long time, the hardest part was hitting all six threaded rods at the same time, without enough access. The primary did eventually slip on.

Next up was the secondary, but that proved to have other interesting problems. We have not tried to move the elevation very much, and it turned out that the imbalance was pretty bad. Al did something clever, which was to use the anchor points to ratchet down the elevation enough to first mount some weightlifting weights, then get the secondary in.

Incredibly, the secondary went in without indecent, but the boom looks funny with the weight hanging. They also ended up removing about 1500 lbs of counter weight, so now the boom is easier to move.

On another note, flies have made it to the site, and so have some anti-fly measures. This particular device sounds horrible. A fly attractor-filled bag is filled with water, and when the flies enter, they drown. The bag is supposed to hold a thousand flies.

The most hilarious thing that happened today was Marius spilling the fly juice on himself while trying to mount the fly trap. Yum.

Overall, a very productive day, and the telescope finally looks like a telescope. Tomorrow the outer ring shield panels go on, and it should really look cool.

Adapers again

2009-06-24T23:35:00.000-07:00

Hans came back last night with the adapters, each one machined perfectly by the scripts machine shop, all except one because I was off on my request by 0.005". I ended up spending some quality time with a die grinder, paddle sander, and socket #3 in order to get that adapter in.
Here is a shot off all the smaller adapters in the secondary. You can see that they all fit in, but there was still one problem, they did not all fit all the way into the sockets.

The GD guys fixed this by grinding a bevel on all the adapters. Six or so hours later, all the adapters fit in, but we then ran into another major problem.

After Al tried to bolt in the adapters into the primary, he found that the tapped holes into the primary where nowhere near straight. This was a pretty dark moment when I saw this.

The solution shown here, basically drill out the adapters, and use washers instead of a countersunk hole.

One large pile of steel spaghetti later, and most of the adapters are finally in. There are still a couple left to do, and the GDSatom guys will finish them tomorrow, beginning at 6am! BZ is supposed to show up tomorrow, and we should finally install he mirrors.

On another note, Marius has joined us, and he drove his Focus up to the site in second gear with his car filled with 80/20. True to form, he had not eaten all day.

Two SZA observers from Huntsville visited us and Esra took this rare photo of me to prove that I am actually here. No wonder why the GD guys call us the geek squad. Those enormous sunglasses are giving me the best tan lines. Notice how clean Marius looks. Thanks Esra!

The lower boom

2009-06-24T00:33:00.000-07:00

In addition to fussing over the mirros, Al has been preparing for the last part of the major assembly, installing the lower boom. Al got a lift bucket to show up today, and we should have it for the next month. The bucket made it a lot easier to do all the bolts on the main boom flange. It is quite a piece of equipment, and we had to disconnect the power in order to get it in place.

BZ prepared by leveling the boom. We learned from our earlier mistake- you shouls lift parts as level as you can before trying to assemble.

Here is the lower boom in the air. Daniel is running the tag line, and Brian is in the upper boom ready to use the spud wrench to get the holes to line up.

After banging all the bolts on with a very loud impact wrench, they went to install the reflector Backing structure.

And finally, this is how it was left. Assembly can go very quickly if all the parts are lined up. We are now only held up by trying to get the adapters into the mirrors, and I was up there trying to do some more grinding. I was up there late enough to get the sun setting over the sierras onto the boom. The sun sets really fast these days.

Adapters and mirrors

2009-06-24T00:18:00.000-07:00

This is what has been driving us nuts for the past week. Do any of you remember how worried I was that we did not install the mirrors in Italy?

Well, it has come back to bite us. Both the mirrors are supposed to have these precision machined sockets that accept stainless steel adapters used for adjusting the mirror position and allowing for contraction. They problem is that it is supposed to be a tight fit, and as you should know by now, if you need a tight fit, both parts have to be in the same place during machining.

Well, the adapters were made in one shop, and the mirrors in another, so the parts were never test fit. To make matters worse, the walls of the sockets are not very nice, with casting defects and bit chatter.

We sent Hans back to UCSD to pull of an emergency machining job on Saturday night. We got word from Eric that he wanted no more than a 0.005" clearance, so we had to measure each socket with an inside micrometer. If you have ever tried to do this, you will know that it is darned hard to do. After Daniel spent a couple of hours at it, the Vertex guys suggested another technique and I was basically able to reproduce Dan's results. You can see from the photo that the sockets are not very circular. We will probably have to shim to make the difference, we wont know how bad we are until tomorrow.

This is Brian going over the secondary sockets. They were not as bad as the primary, but they are still not circular.

If you want to freak me out, you should bring a grinder near the primary. The sockets on the primary are bad enough that we had to grind down some spots with a die grinder. Al was really good at this, but I had trouble getting into the crack to get out a little ledge that each socket has. We will not know if it is good enough until tomorrow.

Hans is back tonight witht he parts, so we will learn a lot tomorrow.

A note about dirt

2009-06-24T00:05:00.000-07:00

It is really dirty at Cedar Flat. Even worse than I remember. This is what you look like after one day of working outside.

I have a raging farmers tan. On top of that, I come down covered in dust, and it makes me look even more tan.

The first post

2009-06-20T12:22:00.000-07:00

The explanation:

This is supposed to be the log that I am keeping for the Polarbear deployment in Cedar Flat, near Bishop CA.

I do not expect to keep this bleedingly up to date, but if enough people are interested, maybe there will be more updates. I hope that most of the team member will eventually start contributing. Also, this is meant to be semi-public, so there will be a mash-up of technical and not-so technical information.

Most of you already know this, but Polarbear is a project that will study the nature of the early universe as seen through microwaves left over from the big bang. The project has been about a decade in the making, and I got involved about six years ago.

We are initially installing the instrument at Cedar Flat to test out all the systems. The idea is that the Sierras are easier to work in and reach than the eventual site, the Atacama desert in Chile.

2009-06-20T00:14:00.000-07:00

I am realizing that this blogging thing is going to take a lot of time, so it is not going to happen tonight. So to cut to the chase, here are some photos form the first week for you:

PBT week 1

Day 2, container arrival and unpacking

2009-06-16T23:22:00.000-07:00

I am posting this from memory that is one week old.

On Monday, Peter was in LA at the docks overseeing the initial unloading of the major components onto flatbed trucks. There were initially 3 containers, but one was overweight for California roads, so Peter opted to unload the major parts onto flatbed trucks.

We met the containers in Big Pine. I had to look around town for 3 out of 4 of the containers. We had told them to meet at 395 and 168, near the trailer park, but some of the drivers decided to park and sleep in an empty lot. Luckily, it is pretty hard to miss a telescope in the middle of Big Pine.

Driving up the road to Cedar Flat was a minor adventure, there is a narrow pass where the road necks down to one lane. Peter and Albert drove ahead to make sure the path was clear before they let the four trucks through. Those drivers were pretty impatient to get up there.

I took a photo from my iphone on my way up. This is the beginning of the scary part. You cannot see what is coming around the corner.

After the trucks arrived, the Vertex guys dug right in and started unloading. The first problem was that the Mirrors boxes were stuck next to each other an needed to be pulled apart. Peter decided to use a somewhat unconventional approach to separating them, but it seemed to work fine.

Daniel was then eager to jump in between the crates to thread the harnesses for lifting.

Another odd thing about the packing was the the lower boom was too large to lift through the top of the container. BZ, the crane owner and operator had to thread the boom all the way to the back of the container, while Daniel guided it though and Albert gave hand signals on how to move it.

Overall, it only took 4 hours to unload the truck and send the drivers off barreling down the highway. There was enough time left to place the tower onto the pad. We had the CARMA staff pre-intall the mounting bolts into pad 25 from drawings. Everyone was nervous that they would not be in the right spot. The problem is that the pad is not flat, it is pitched to shed rain. This also confuses us a little, because Peter wanted to use this fancy ancient optical level to set the hight of the feet. Apparently, you can get 0.001" accuracy with the level.

Mountain Polarbear

The Water Chiller

Almost there

HTT at JAO dedication

Unwelcome Visitor

Observations

Hair cut

Automated operation

Days 17-19, First Light!

Days 12-16, Cooldown

Day eleven: Mounting the Receiver

Second Week: Receiver Assembly

Receiver assembly, the first few days

First Day Unpacking Cryostat

In Memorium: Huan Tran (1974-2009)

Polarbear Telescope Assembly is FINISHED

Painting the box

Scorpion

Repainting the Structure

Elevation motor counterbalance

The perfect polarbear picture

some more critters

Servo Selloff

Track beam mode

Observation scan

Balancing the Telescope

Servo tuning

Elevation drive alignment

BBQ

Unlikely Visitor

Secondary Adjuster and cable wrap

Air conditioner saga

New car

counterweights and controller

Track beam problems

Assembly almost done

Fire and rainbows

Photo catch up

Polarbear dance moves

Telescope moves!

Photogrammetry

Panels and countrerweight

Old Photos

New tabs and counterweight

Dave's Turn

Star Destroyer

80/20 madness

Marius is very dirty

Back in at the mountain

Fauna

More mirror problems

Last Crane day

Adapers again

The lower boom

Adapters and mirrors

A note about dirt

The first post

Day 2, container arrival and unpacking