Sunset left a beautiful sun pillar at Paranal tonight.

Twenty hours in the air, a few more in trains and taxis, and a brief overnight stay in sun-drenched Santiago: that’s all it takes to get to one of the most amazing places on Earth for astronomers, Cerro Paranal. Home to the VLT, VISTA and VST telescopes, Paranal is a big epicentre of astronomy in the Southern hemisphere, or indeed the world. I’m spending much of the next week here in Chile on a kind of reconnaissance mission for the GRAVITY project. 12 hours into my stay I have already forgotten the drudgery of airport security queues and whatever body clock issues I’m having, and I’m having a thoroughly good time.

GRAVITY is one of 2 second-generation instruments for the VLT Interferometer (VLTI), in which light from multiple telescopes is combined to beat the resolution limit of one single telescope. Interferometry is commonly used in radio astronomy, but for optical and infrared observations it’s extremely challenging. VLTI is one of the only large facilities offering such a mode.

The GRAVITY instrument will combine the light beams from 4 telescopes to carry out high-resolution observations in the near-infrared, particularly with a view to tracking the fast-moving stars close to the black hole in the centre of our Galaxy. Like so many instruments today, it’s a big project with 6 institutes involved and many subsystems that are all highly complex individually, yet they all have to play together nicely with a common goal. At MPIA I work as systems engineer for one of those subsystems, a set of 4 new wavefront sensors  for the adaptive optics systems on each of the four Unit Telescopes.

Because these sensors need to interface with lots of existing hardware and control software at the telescope, I’ve come on a fact finding mission to learn more about how certain aspects of the telescope and the interferometer are operated today, so we can optimise our strategy for the GRAVITY instrument.

The VLTI delay lines

It’s my first visit to Paranal and I’m excited to be here. The great thing about engineering visits is that I’m not as restricted as “regular” visiting astronomers (those who successfully applied for observing time for their science), and I really get to look under the hood. Most observers don’t get to come here for 5 days either. Within 15 minutes of arriving an engineer took me up to the telescopes, I’ve seen the Coudé lab below one of the telescopes where our sensors will be places, the VLTI delay lines (which are amazing, pic above for the aficionados), the VLTI instrumentation lab. Tonight’s astronomers were out of luck as the sky clouded over around the time of sunset, so when I came back down for dinner the domes remained closed. The sunset sure was pretty though!