Gearing up for the Next Generation Transit Survey

Posted by: mattburleigh | March 21, 2014

Gearing up for the Next Generation Transit Survey

I’m in Geneva at the moment, visiting the Observatoire de Geneve with my colleague Mike Goad and our PhD students Andy Grange and Alex Chaushev, to learn how to put together, set-up and commission the telescopes for our new exoplanet project, the Next Generation Transit Survey (NGTS). In a few months time we’ll be travelling to ESO’s primary observatory at Paranal in Chile to install the 12 telescopes that will carry out the most sensitive ground-based survey for transiting extra-solar planets yet. As its name suggests, NGTS is a successor to the highly successful SuperWASP survey, which has found over 100 Jupiter and Saturn sized worlds since 2004. With NGTS, we aim to find Neptune-sized worlds around stars that are bright enough so that detailed follow-up studies can be made of them: radial velocity measurements to get the planets’ masses, and transmission spectroscopy and other techniques to study the planets’ atmospheres. If we’re lucky, we may even detect smaller “super-Earths” around red dwarf stars. Although NASA’s Kepler mission has found thousands of candidate exoplanets, many of them Neptune-sized and smaller, including candidate rocky planets, most of these worlds orbit stars that are too faint for such follow-up work. NGTS will fill a gap between Kepler and two newly approved space missions designed to try and find genuine, potentially habitable rocky worlds around nearby bright stars, NASA’s TESS and ESA’s PLATO .

The radius of exoplanets discovered by various projects (in Earth radii) versus the brightness of the star (remember, bigger number means fainter!).
NGTS is sensitive to finding transiting planets in the orange zone. The purple dots are Kepler’s planets, and are mostly found around faint stars. The SuperWASP planets are the pink dots, and the named planets are the most famous and well studied transiting ones. We want more of those!

NGTS has been funded by a consortium of British universities (Leicester, Warwick, Cambridge and Queen’s Belfast), together with DLR Berlin (who lead the PLATO mission) and the Observatoire de Geneve. Our major contribution at Leicester is to test and characterise the CCD detectors in the labs in our Space Research Centre . In essence we’re treating the detectors as we would those for a space mission, by trying to understand their behaviour at the most detailed level before they go on sky. This will help us to achieve the milli-mag precision photometry we are aiming for to detect small exoplanets. Indeed, the work has been very successful so far, and led to strong improvements in the detector performance with the aid of their supplier, Andor. This lab work is mainly being done by Andy Grange as part of his PhD thesis studies.

Rendering (by Richard West) of the suite of NGTS telescopes in their shed at Paranal, Chile

NGTS will consist of a suite of a dozen 20cm F/2.8 telescopes manufactured by Astrosysteme Austria (ASA) simultaneously observing the sky from ESO’s Paranal observatory, the home of the four 8m Very Large Telescopes.

One of the NGTS telescopes in its mount on the roof of the Observatoire de Geneve. The CCD detector is the light grey box on the side of the telescope.

For the last year we’ve had one of these units running on the roof of the Observatoire de Geneve to test and develop all of the hardware and software systems. Meanwhile, in Chile, the land has been levelled and the concrete laid ready for the arrival of the telescope building, which is currently being shipped from its manufacturer in Devon. The current timetable is to begin installing each mount and telescope from July, but in order to do that we need to learn and practice not only putting the hardware together, but the procedures for aligning all of the optics and the detector, perfecting the telescope pointing on sky, and taking the first data. Which is why we’re here in Geneva this week! It’s been a real pleasure to get out of the office and the lecture theatre, away from the stress even if just for a couple of days, get a spanner in my hand and actually do something constructive. And it’s great to see my colleagues so enthusiastic. We had a lot of fun yesterday, and capped it by spending a few hours on sky in the evening testing some of the pointing and calibrating procedures. Followed by a cheese fondue and some crisp local white wine!