Fauna

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.

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

More mirror problems

Another day, and another problem, but first,

We had lots of visitors today, Adrian brought the family, Mary brought us some much needed water, and Brian and gang flew in from many locations and told us to eat at the Thai place at the airport. There were lots of people on site, and it surprisingly did not feel that crowded, but I have to remember to get more hard hats.

The Servo also showed up, and it was like Christmas. I forgot to take pictures, but GD packed the heck out of those crates. I am really into packing material, and these guys really outdid anything in my imagination.

Marius and Daniel toiled in the sun to put together his box- the one that had been taking up space in the lab for months. They even took off the wrapping plastic. It looks like it actually went back together as it was supposed to.

Now on to the next problem. The GD guys spend most of the day trying to install some threaded rods into the ring shield panels that go around the primary. The actual part differed significantly from the original design, so the posts did not at all line up where they were supposed to go.

After trying to place just two of the panels, we figured out what the problems was, and maybe tomorrow we will try out a possible solution involving spherical washers. Stay tuned to see what happens.

And now for the random image in the Bishop Super 8 parking lot-

I thought I had escaped these things when I left the bay area.

Last Crane day

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

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

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

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

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

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.

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

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.