Thursday, 13 June 2013

Welcome to La Palma (Guest blog)

We are currently sat almost 2,400 m above sea level with the clouds beneath us, staring at some of the world’s leading observatories.  My name is Martin and I am here with my colleague Alastair.  We are both graduate engineers from the UKATC in Edinburgh, and are currently here as part of a placement scheme within the STFC graduate training programme.

Martin, optical engineer
Alastair, mechanical engineer

La Palma is the western most of the Canary Islands, and one of the best sites for Astronomy in the world.  This is partly due to the local weather system and latitude, which means that the clouds usually form at around 2,000m and thus below the peak of the mountain.  The high altitude also means that the distortion, or twinkling, of the light coming from the stars is reduced as there is less atmosphere for the light to pass through.  The island has been used as a site for Astronomy since 1979, and as such there have also been measures to reduce light pollution on the island.

The mountain top site is shared by several institutions, collectively known as the Roque de los Muchachos (The Rock of the Boys) Observatory.  Some of the telescopes of note here include the Swedish Solar telescope (below right), a 1m diameter telescope with an advanced adaptive optics system (allowing it to correct for atmospheric distortion) for observing the sun.  The highest telescope on the mountain is the Nordic Optical Telescope (below left), a 2.56 m diameter telescope first opened in 1988.  There are many instruments that constantly swap on and off this telescope, researching lots of different areas of Astronomy; from asteroids to galaxies.  The dome of this telescope is unlike any of the others in that the entire building rotates with the telescope!  We have been told by some of the astronomers here that this can be very disorientating when you try to access the building in darkness and aren’t sure where the door is anymore.
Nordic Optical Telescope
Swedish Solar Telescope


Two of the most eye catching telescopes here are known as MAGIC I and II.  These strange looking telescopes have huge metal mirror and no dome, and are designed to detect Cherenkov radiation caused by high energy particles entering the atmosphere.  They are operated by over 20 institutes from across Europe.

Roque de los Muchachos is also home to the world’s largest single aperture telescope, the Gran Telescopio Canarias.  The main mirror of this telescope is made up of 36 hexagonal segments, each around 2 meters across, making up a single mirror 10.4 meters in diameter.  When visiting we saw the other 6 segments they have in various stages of having their reflective aluminium coatings removed and replaced.  Due to the sand in the air here the mirrors get dirty over time, and even with regular cleaning the coating still needs replaced every so often.  By having a continuous stream of this happening, there are never any segments missing from the telescope.  Also of mention is the oil bearing on which the telescope mount sits.  This is so low in friction that it is possible, when the drive system is turned off, for a single person to push the telescope and its mount (around 400 tonnes) around by hand!

There are several other telescopes on the mountain not yet mentioned, and several of them are from UK institutes.  These will be covered in further blog posts over the next couple of weeks.

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