A deluge of data

20 September 2016

Interview with

Dr Nicholas Walton, The University of Cambridge

We just heard how Gaia is busy in orbit collecting data, but then what? Well, it Numbersbeams this data back down to earth - and this is where the teams on the ground get to work - getting it ready to be released to the world, as happened earlier in the week! Georgia Mills went to the Institute of Astronomy in Cambridge, on the big day, to meet someone who has been working on Gaia's data for several years...

Nicholas - I'm Nicolas Walton. I'm a member of the ESA Gaia science team and I'm here at the Institute of Astronomy in Cambridge. So there are seven so-called data processing centres across Europe; we have one of those here. It's one of these large, big data type activities and we've got a rack of computers in a sort of super computer setup in the Cambridge data centre and we take the data that comes to us from the European Space Agency where we photometrically calibrate and analyse that data. Once we've applied all our calibrations we send that back to ESA and it's combined with a set of data processing outputs from other centres and, eventually you get the final catalogues such as we see today.

Georgia - Before we get to the actual science people will be doing using this data set  - what have you been doing to this data? You say calibrate but just elaborate to me, what does that mean?

Nicholas - So if a star goes across the focal plane array the starlight is detected by the charge coupled detectors and each star going across generates what could be a little spectrum or a little image that gets sent to the ground. But that's in some arbitrary units and we have to convert that into something where we can flux calibrate that data so we can turn something into a known calibrated object. So we can basically say if something was bright, if something was faint, how bright in real physical units.

And we are responsible for removing a number of the artifacts in the data acquisition. So for aspects such as a scattered light or various positional movements which might affect the flux calibration.

Georgia - Basically, a lot of work for a lot of people. Gaia sent down billions and billions of data points to process, and by processing things like the brightness, the distance, and even the colour, this helps work out what kind of object it was seeing. And the first lot of this data got released this week - happily coinciding with Gaia's birthday.

Nicholas - Gaia itself was launched at the end of December in 2013 so, in fact, today is one thousand days exactly after the launch of Gaia.

Georgia - Is it a nice feeling to sort of have the world be able to see all this data?

Nicholas - Yes, so it is. It's great to see a really excellent data set, a really excellent set of data which is going to help so many people write so many decent papers, and discover so many new aspects about our galaxy, and how we are and where we're going.

Data release one in many ways sets the scene for what's coming. It shows that  Gaia works, it shows that all the processing systems work; it shows the data is very high quality; it gives us a taster catalogue of two million objects; it give us a map of a billion objects. And as we go on with further future releases, we add more richer information about each of the objects that we observe so we get information about the spectra so we can classify. We can say this star is this hot, or it's a giant, or it's a dwarf star, or it's an active star, or it's a planet, or it's near Earth object - oh we'd better look out, that sort of thing. So we've got a lot of exciting new data coming out.

Georgia - So with this data release it's just been thrown out there to world. Who are you expecting is going to be using this data and what for?

Nicholas - Well I think many, many, many astronomers across the world are going to be using this data be they're looking at stellar astrophysics, be they're looking at planets around nearby stars, be they're looking at our solar system, and looking at dark matter, linking to cosmologies, and so forth. So, well perhaps not the entire, but a large fraction of the astronomical community will be looking at this data.

But it's also good for those interested in the public to take a look, especially when the maps of the 3D Milky Way come out. You'll get an idea of where we are in space and time.

Georgia - I mean I cannot wait for someone to build a virtual reality Milky Way for me to fly around in. Is that on the cards?

Nicholas - That's coming. That will be there. I think the technology will be there to fly around in your VR universe.

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