Saturday, September 21, 2013

Astronomy: Observing at VLT


A few weeks past, I went up to Cerro Paranal to observe with the Very Large Telescope (VLT). I was there with my officemate, Jackie Faherty, who was the PI of the program. Given that this was our first experience with the instrument (FORS2), I tagged along to learn about it and to help in any way that I could.

This blog recounts our brief adventure there.

Each observatory is different. Generally, though, they can be quite isolated with only a few people around. It was good going in with someone who had already been there several times, so Jackie was able to show me the ropes very quickly. However, VLT was actually rather crowded with plenty of people around, including staff, engineers, and astronomers for short or long term stays.

The entrance to la Residencia

The facilities at Cerro Paranal are outstanding. The Residencia, where you sleep, eat, and stay most of the time, is partially underground so it feels as if you are going into a dark bunker as you walk towards it (see above). It was featured at the end of the James Bond movie Quantum of Solace.
However, once inside you are shocked by what looks to be almost a tropical resort. There are lots of trees, a pool, the walls and decor are very nice and fancy. The humidity is kept very high, given that outside it is rarely above 10%. So it feels very tropical inside the building. It feels like you are checking in to a fancy hotel.

Inside la Residencia. Not what you would expect at an astronomical observatory...

We arrived two nights prior to our run, so we could prepare the observation blocks (OBs), finalize the target list, and adapt to the higher elevation. On the first night, we went up to see the control room and to check out the telescope. There are four 8-m telescopes at the summit, the one we were using was UT1 aka Antu (the word for Sun in the Mapuche language). While opening the dome, the telescope was moved around so we could see right at the mirror. It was all very impressive.

Jackie and me at the UT1. The telescope mirror is 8-meters in diameter: big! Picture credit: Jackie.

For our observing run, we were allocated the second half of the night. However, to avoid driving up in the middle of the night, we were recommended to go up before sunset and just spend the full night. I filled up the time working on some other projects and, once we got some data after the first night, worked on this one, which was good. We started sometime after 1am and, as with any observing run, I was tired by dawn. It didn't help that our observations consisted of fairly long integrations. So once we set the target, we could just sit back for an hour or two or three and wait. It makes for a very easy observing run, though.

The UT1 station at the VLT control room. All telescopes are operated from the same control room.

One of the things I'm still not used to is the header structure for the ESO data files. They don't play very nice with the tools I'm familiar with (such as IRAF), so it takes a bit of extra effort to get the information you want from the files. Still, with the time there I created a few scripts to make things easier. My self-appointed task was to examine the data, reduce it, and see if we could measure the quantities of interest. I was spot-on with the standards, which leads me to believe that the methods I used are working, though I know they can be improved. We'll have to closely check the brown dwarf targets, but for this quick look we were very happy with the results we were seeing.

Overall, this was one of the best observatories I've been to. The Residencia is a ridiculously luxurious facility to stay at and the telescopes are among the largest in the world. Combined with the pristine, dark skies of Chile, this makes for excellent observing conditions. I hope I can come back for a future observing run!

The moonless night sky is amazing at Cerro Paranal. I'm not too skilled with editing RAW pictures, but I think this came out great. Click to see a larger version. Picture credit: Jackie.

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