Monday 11 July 2011

Final resting place

If you've been following this weblog, you'll know that we've received quite a few (although not all) of the LOFAR HBA tiles for the KAIRA project. Additionally, you'll also know that KAIRA is not something by itself, but makes use of the same tile technology as all the other LOFAR stations that are scattered around Europe.

Each of these tile arrives at the site sealed up. For there, they can be moved, unwrapped and deployed. The tile in the photograph on the left arrived on the first day as part of the first delivery. At the time, we noticed it has some strange writing on the side of it. But, being under the plastic, we didn't want to unwrap it before it was time to put it on the field. And, as we were still waiting for some parts (in particular the tile cover sheets), we could not start deploying the tiles immediately. As a result, we received more deliveries and this tile with the odd inscription became buried in the stack of other tiles on the site.

However, on Friday 8th July 2011, we had managed to get through sufficient tiles on the storage stack so that this was the next one to go. And then we learned the story of the secret message enclosed in the covers of this particular HBA tile.

Well, it turned out that this was the 'last tile'. Tile number 2824.


There are a lot of LOFAR stations and that means there have been a lot of tiles produced. Although not all stations have been completed (we're one of them), at some point the production run was completed and the moment that the last antenna tile left the production line and the work ended was, no doubt, a special moment. As a result, the team who produced it decided to put a message on the side of this last tile, as a mark in the history of this phased array project.

The production team on that tile comprised: Renske, Kelly, Han and Zabet. And, as it turned out, Han was actually on the site helping us with the installation work and got to see this last tile get unpacked... the same tile that he had signed last year in the Netherlands.

Han reminisces about making the final tile.

Having had the story explained, it was time to get the tile onto the field and into position. First it is lifted over the unfolding station...

Moving the tile to the unfolding station

Then the tile is lowered down, during which it opens out and will lie flat ready for fitting.

Han helps unfold the tile.

The fitting process means checking the antenna, checking the polarisation of the antennas, removing any remaining packaging and sealing up the sides with some spikes. This last step would mean covering the message, so we stopped at this point for a photograph.

The full message reads:
05-11-2010 ZAbET
TILE 2824

And, it small letters under TILE 2824, it reads:


Then the remaining lids were fitted and the lifting rigs attached. Note the bar-code on the side of the plastic: HBAT-01009-00048.

HBAT-01009-00048 is prepared for lifting

Meanwhile, the batons on the frameset were being fitted, ready to accept the tile.

Final preparation work on the frameset.

The tile location where this tile will be deployed is H67.

With the frameset ready, the tile was brought on to the field. This is done using the HIAB on the lorry, which then drives down one of the columns. There is a person in each corner to help steady it.

Guiding the tile onto the array.

Once in place, it is lowered into position. A brief moment is taken to get the alignment spot on and then the lifting equipment can be disconnected.

Removing the lifting straps and jigs.

However, that's the quite the end. Each tile is covered with the plastic top-sheet. This is hauled up onto the tile and fixed around the edges.

Putting the cover on.

With this done, the final tile from the final production run was in place. (Again, a chance for a photograph.)

The 'Tile #2824' installation team are from left to right: Eero Rantakokko,
Johannes Turunen, Jussi Paulamäki, Han Wessels, Santtu Rantakokko
and Arttu Jutila, with Mikko Tilja seated on the ground at the front.

Although we are only about a quarter of the way through the installation of the KAIRA HBA, this is a significant moment. The last tile produced has now been put in place and the other tiles that are still in storage (both for KAIRA and the few remaining Dutch LOFAR stations) are soon to follow.

No doubt, there will be causes to celebrate in future, with the completion of the array, the first signals and the first results. However, this is a chance to acknowledge the hard work of the people who made the tiles in the first place. These are the designers, the engineers and the technicians who worked in the design office, the factory and the assembly areas to get them produced. Much thought, effort and time has gone into making the LOFAR production system so successful and so, on behalf of KAIRA (and I'm sure on behalf of countless scientists, engineers and students who will use these antennas), I would like to say a big THANK YOU for all your hard work... we really appreciate it.

Dank jullie wel!

Thank you!


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