Diving Deep

August 23, 2007 — Leave a comment

A recent BBC News article has prompted a couple of people to mention ‘this thing called SCUBA’ to me. The article is about the new SCUBA-2 submillimetre camera that has been built at the Royal Observatory in Edinburgh (with more than a little help from Cardiff University and a couple of other places).

SCUBA-2, as the name might suggest, is the successor to SCUBA which stands for Submillimetre, Common-User Bolometer Array. What does that mean? Well basically this is a device that you connect to a telescope and then record images of the sky.

Its submillimetre because it will record information in the 850 micron and 450 micron wavelegnth regimes (i.e. 0.85 and 0.45 mm). Its common-user because a) lots of people can use it and b) it makes a nicer acronym than SBA. Its a bolometer because… well its a bolometer; and finally its an array of detectors put together to make the pixels of an image.

SCUBA-2 is hopefuly the camera which will provide me with data for my PhD thesis. I have been working with SCUBA data sine I arrived at Cardiff back in September last year. I may even publish a paper based on my work so far. However the data from SCUBA will look tiny compared to that which will come from SCUBA-2.

scuba1images.png

Two of my own images from SCUBA data. Both of these show star forming regions inside dark nebulae.

The new device is incredibly powerful by comparison to the original. The BBC News article states that it will be a thousand times for powerful, but there are many ways to measure ‘power’ in this kind of instrument. SCUBA-2 will be able to map the sky 720x faster than SCUBA. So where it used to take hours to obtain maps, it will now take minutes. SCUBA-2 has a field of view at least 13x greater than SCUBA, which means you get more in each map. SCUBA-2 is also going to be twice as good at detecting point sources, which means it is going deeper into the sky.

scubas.jpg

Left: SCUBA, which is about a metre and a half tall. Middle: Me leaning on SCUBA-2. Right: The receiver end of SCUBA-2.

SCUBA-2 is going to moved to the JCMT telescope in Hawaii in October where it will be fitted to the receiver of this 15m scope. This process takes months and afterwards the deice will have to undergo what is called commissioning, where it is essentially calibrated and readied for proper use. all in all we can expect the camera to be in full use in around a year or so if we’re lucky.

SCUBA-2 will be acting as pathfinder for the upcoming ALMA. ALMA is an array of submillimetre scopes in Chile’s Atacama desert – one of the highest and driest places on Earth. This array will use the surveys done with SCUBA-2 to go deeper than ever into space using an array of 76 telescopes which will combine to give a clarity of image 10x that of the Hubble Space Telescope.

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