What do I do?

As promised last time here is a bit of a description of what I do for a living, which also marks the first entry in the Astronomy section of the blog. Since November 1st I’ve been working for the UK ALMA regional centre or UK ARC for short as a Post Doctoral Research Associate.

First of all what is ALMA? ALMA stands for Atacama Large Millimetre/sub-millimetre Array, which when complete will be an array of around 60 12m telescopes combined into what is known as an interferometer.

Telescopes get better resolution the larger the diameter of the dish (or mirror if you like the optical wavelengths) but for the kinds of resolutions astronomers want nowadays building telescopes big enough becomes a practical impossibility, not to mention a financial one. Luckily the technique of interferometry exists, this works by taking two or more dishes separated by some distance and combining the signals they recieve. The resolution of an interferometer is dependant on this separation, as if you had one massive dish of equal diameter to the separation distance. The downside is you are only getting information the parts of this “massive dish” from the two points where the small dishes in your interferometer are, as such you won’t get a true representation of the part of the sky you are looking at.

So the more dishes an interferometer has the better your image of the sky will become. But instead of building thousands of dishes next to one another (things would start to get expensive again) you can take observations of an object over a number of hours. The position of your telescopes will have moved with respect to the bit of sky you are looking at (due to the rotation of the Earth) effectively filling in more bits of the “massive dish”, giving you an even better image…. I’ll just let that sink in for a bit…

Ok, back to ALMA! ALMA works, as its name suggests, at mm and sub-mm wavelengths (a few 1000 times longer than the wavelengths of visible light) and here Astronomers are looking at the electromagnetic radiation emitted by a myriad of molecules in interstellar and intergalactic space! For distant galaxies the emission we will be seeing from will have been stretched (or redshifted) due to their movement away from the Milky Way into the ALMA frequency range. For objects in our own Galaxy we will be observing all kinds of physical processes such as the formations of massive stars at levels of detail previously unseen.

The telescope is being built in the Atacama desert in Chile at an altitude of 5000m in one of the driest places on Earth. This make it an ideal site for the mm wavelength observations that will be conducted there as electromagnetic radiation at these wavelengths can be highly absorbed by water in the atmosphere. So high up == less atmosphere and dry == less water in what atmosphere there is.

So day to day, I am at the Jodrell Bank Centre for Astrophysics where I work on ALMA testing the new ALMA software, building up knowledge of how to work really well with the data coming from ALMA (there are currently a handful of telescopes working at the site) and taking part in community days with members of the Astronomy community getting ready for when ALMA starts taking data for real scientific observations.

Finally, within the next few months I’ll be on the Jodcast which I occasionally edit talking about what I do. I also tweet professionally (if that can really happen) about the UK ARC at twitter.com/UK_ARC .

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