Sky at Night presenter
Maggie recounts her experience controlling one of the world’s great observatories when The Sky at Night visited La Palma.
When people think of the Canary Islands the usual image is Sun, sea and sand, but on the island of La Palma, things are quite different. At the Observatorio del Roque de los Muchachos, 2,400m above sea level, a collection of some of the largest telescopes in Europe keeps a vigil on the skies.
It is the ideal location: a dormant volcano, very little light pollution and some of the clearest skies in the world – up to 300 clear nights a year. Due to these great conditions, 14 astronomical facilities are located here, with many different types of telescopes, and for one night only we were given the run of the place on behalf of the Sky at Night audience. Armed with a list of requests from
Sky at Night viewers, we were able to use its telescopes to gather data. Chris Lintott used the Liverpool Telescope, owned and operated by Liverpool John Moores University. It is a 2m optical telescope that’s fully automated, allowing it to be used by professional astronomers across the world, as well as schools in the UK and Ireland. Its automated nature makes it very good at responding to transitory events such as supernovae and gamma- ray bursts; it has a reputation for being first on the scene for many of these events. We programmed it to capture an image of the Waterfall Nebula.
We also received many requests to take an image of a galaxy, and to get this I had the honour of using the largest single aperture telescope in the world, the Gran Telescopio Canarias. This is an impressive beast with a primary mirror 10.4m in diameter, made up of 36 hexagonal segments. The segments are supported and held in place by a 40 tonne armature. All this weight glides smoothly into position on the required point in the sky thanks to the scope’s oil-pumped hydraulics.
With its huge mirror, the Gran Telescopio Canarias is designed to look at some of the faintest objects in the night sky. It is sensitive enough to be able to pick up just a few tens of photons per hour and, due to the high efficiency of the optics and detectors, it can look back in time to objects billions of lightyears away. Observations like that take weeks though, and with our time limited to just one night we chose a request to image a nearby galaxy some 30 million lightyears away.
At the CCD readout we were amazed at the details that could be seen: bright stars of our Galaxy in the foreground, the galaxy NCG 891 and then a collection of distant galaxies scattered in the background. The raw data looked fantastic, but then more time was spent processing the image and adding further data captured with a range of wavelength filters to finally produce a beautiful colour image. Our time at the telescopes was short, but we were able to leave with a wealth of data and images that reflect a voyage of discovery charted by the viewers. Thank you for your requests!
La Palma’s unusual geography means the observatory often remains above the clouds