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Exoplanet Hunting NGTS Telescope Array Achieves First Light
Zothecula writes The Next-Generation Transit Survey (NGTS) array, built by a UK, German and Swiss consortium, has achieved first light at the Paranal Observatory in Chile. The installation is designed to search for exoplanets between two and eight times the size of Earth, studying them as they pass in front of their parent star.
Many years ago when I was in university and hung out with astronomy nerds ... the notion of discovering an exoplanet was still speculative science, and it was largely thought there wouldn't be many planets.
Flash forward, and exoplanets are real, documented, and numerous.
It's awesome to see how much our understanding has changed in the last 25 years or so. And the more we discover about the universe, the bigger and cooler it actually is.
And, just think, only a few hundred years ago you'd be burned at the stake (or whatever) for saying the Earth goes around the sun.
Lost at C:>. Found at C.
I would say it's observation time on thousands of potential targets. Who's going to do it?
You don't need adaptive optics or anything fancy, exoplanet hunting is (mostly) measuring quantities of light. Whether that light's been bent a little through the atmosphere and lands on a nearby pixel makes little difference. All you end up doing is using a larger photometric aperture (a circle of pixels that you consider to be the star). Adaptive optics is useful for other things, but for transit detection, meh. Observatories regularly defocus stars (into donut shapes) if they're getting too much light from a star in the field - this is a surprisingly common problem with huge mirrors.
You can observe exoplanet transits with a DSLR and a small telescope if you have the patience. It's a matter of finding bright stars. Again, you're not going for high resolution or magnification, you're just measuring light. By taking repeated observations, binning your data, phrase-wrapping (by plotting the data as a function of orbit phase) you can increase your signal to noise. The signal is maybe 0.001% of the light, but if you measure 1,000,000 counts then that 1000 count dip is probably above the noise.
Big observatories cost a lot of money to run and are highly competitive. If you have an extremely strong case for a follow-up observation (e.g. Kepler spotted something and you want to observe it further) then you can get time, but really we'd like surveys that will stare at hundreds of thousands of stars for months on end. Amateur networks like the AAVSO (variable stars) are very valuable because they provide free, virtually continuous data for hundreds of stars. It's simple, boring work that isn't feasible with big-shot observatories; it would be a waste of instrument capabilities.
Satellites can do this, but they can't store the data, they normally only provide flags that say "this star looks like a good candidate". So the benefit of something like this telescope array is that it can generate vast amounts of data (continuously) and we can actually store it for processing later.
Just a note regarding "can view twelve targets at once".
That's just not the point of a telescope array; rather the contrary. The point is to utilise large number of smaller telescopes to point at the same object to gather more light. This simulates a larger mirror minus the greater atmospheric distorsion they provide. Anything above 12" gets really finicky about distorsion, requiring lasers to help compensate: the laser is used to compare the projected point in the upper atmosphere in order to compensate using adaptive optics. All that is terribly expensive.
The real advancement is in software where all of the (in this case 12) telescopes in the array, are composited into a single image of greater accuracy & resolution.