This is my last night on Paranal for some weeks. Tomorrow I go down to Santiago and on Sunday I’m going to Viña del Mar to help with the conference that Rivi is organising. It will be nice, I hope, even though I will be very tired after the week of night-shift. But Viña is a pretty town with a beautiful beach, and I hope I will find some time to relax there after this turno.

I’ll leave you with some pictures that I took at sunset-time during this week. Around sunset is the hand-over between the day-crew and the night-crew. Usually, people gather to watch it, for some it’s the end of a working day, for the others it’s the last free minutes, before the night and the observations start. And of course, the sunsets up here are spectacular!

People are gathering on the telescopes platform to watch the sunset.

Beautiful clouds, but no observations tonight :(

A triple sun?

Good morning, or should I say good night?

I’m back on Paranal, this time on night duty, observing with the VLTI. The first night is nearly over and I am dead tired. One has to concentrate a lot in these last minutes to not mess up the observations. Astronomical twilight begins in 5 min, and we will still observe a standard star afterwards, and then I have to fill and send the logs, start some calibrations and probably in about 1h I’m finally in bed.

But it’s fun, at least if everything is working. Tonight, we had a lot of problems at the beginning, but at least we got some data with AMBER during the last hours. This is how it looks like:

AMBER observations

These are spectra, wavelength is in y. The first, second and forth window show the light as observed by each of the three telescope that we use tonight. The third window is the most interesting part, it shows the combined light which is brought to intereference. The pattern holds additional information with respect to the individual observations. From its shape and strength, one can deduce information about the shape and size of the star, which in this case is a binary.

Enough for now, the last observation is nearly finished.

One more coffe to keep me going for the last minutes and then good night!
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I’m back from Paranal; for one week I’ll be doing science in the office in Santiago. On Sunday I have to go up again, this time only for a few nights though. So, it’s time to tell you something about the research I am working on.

On Monday, a colleague from Athens arrived with whom I am working. She’s actually a former student of mine and it’s good to see her back now having a PhD We had a small dinner on Monday evening to celebrate this achievement.

The star on which we are working right now is called RR Pictoris. This is a typical name for a variable star. Those are called with the constellation they are in (in this case Pictoris from the constellation Pictor) and some letters or numbers before, depending on when the star was discovered. The first variable star found in a constellation gets the letter “R”, the second “S” , … until “Z”. Then it continues with RR…RZ, SS…SZ,… until ZZ. Then it continues with AA…AZ ,… until reaching QZ (without using J). If this is not enough, the next variable star detected gets called V335 (because there were 334 combinations of letters before, so it’s actually the 335th variable star in the constellation) and of course this can now continue as long as needed. For some very large constellations which contain a lot of stars, we have already reached 4-digits-numbers, e.g. V5580 Sgr is a recent nova that was detected in november 2008 in the constellation Sagittarus. Kind of weird this naming convention, isn’t it?

So our star, RR Pic, was discovered in 1925 when it showed a nova explosion. It’s relatively bright, about 12 mag, and was a naked eye object during the outburst. I have been observing RR Pic every now and then during the last ten years, and it is a very nice object, especially since it is bright enough to try all kind of fancy observations even with smaller telescopes. And the star behaves in an odd way. It’s a variable star (hence the name) and it is known to be a binary. One component is a white dwarf, and since it is belived the more massive one, it is called the primary component. The other one, the secondary component, is probably a normal low-mass star, and the two stars orbit around each other with a period of 3.5 hours. Imagine, two stars orbiting with 3.5 hours period, you get dizzy just thinking about it…

The interesting thing is that these two stars are so close together that the white dwarf is sucking away material from the secondary. This material then forms an accretion disc around the white dwarf and this disc becomse so hot and bright that you hardly see anything else from the system. No chance to see the secondary or the white dwarf itself in the optical. But we can see the orbital variation of the system because we look at it from different directions during an orbit. Also, in the case of RR Pic, the system is nearly seen “edge on”. This means that during an orbit at some point the darker secondary star moves in front of the bright accretion disc and shades part of it from us. We observe this as a small brightness decrease in the lightcurve which is called an eclipse.

Binaries that show such an eclipse are extremely valuable for science, as from this effect a lot of information can be deduced on the geometry of the system, and this helps in interpreting all the other observational effects. Well, in the case of RR Pic it’s not so easy, though. It seems that the eclipse is sometimes there and sometimes it’s not, and so far we don’t know why and when this change happens. We have asked other astronomers who have observed RR Pic in the past for their data, and we now have a huge collection that we want to search for signs of eclipses and also some other features that are observed in this star. And then, maybe, we will understand how this binary works and can apply these results to similar systems. I’ll let you know…
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I am still on duty on Paranal being the official shift coordinator at the moment. This job was called shift leader in the past, but they changed the name about a year ago, so I’m coordinating now, not leading And I am coordinating the various groups that work up here, among them several instrument teams. PRIMA had a comissioning run until yesterday, and Gerard has been blogging about that one.

E-ELT in Close-up View

The other instrument team which is still working up here, are the APE guys. APE is the “Active Phasing Experiment” for the ELT. Now that’s a name to chew on Let’s go back a bit.

ESO is going to build the European ELT a telescope of 42m diameter. 42m, that normally sounds like a radio dish, but the E-ELT will operate in the optical and NIR, same as the VLT is now. However, 42m is too large for a mirror to build. Hence, the E-ELT will consist of segments, as you can see on the picture on the left. That’s a possible design study; I took the picture from this public page of ESO. Now, as you can imagine, to get a nice image from a mirror like this, all segments have to be perfectly aligned. They will be actively supported and aligned always taking into account the actual position in which the telscope is. This is no trivial task and to get some experience with it the instrument APE was designed. APE is kind of simulating the ELT on the VLT. It consists of a small, segmented mirror (see the picture below) which is mimicking a segmented main mirror. So, all the techniques of adaptive optics and phasing that are considerated for the ELT can be tested beforehand.

The accuracy with which APE measures offsets is a nanometer, which is about 1/500 of the wavelength of optical light. Any disturbance whatsoever screws up their measurements. And a distubance is already if someone walks by. This has been a problem at the beginning, because it was not clear to the rest of us that APE is that sensitive. So, we regulary did screw up their measurements. But this is all part of the learning curve, as we like to say here; now we get a call when they start their observations and nobody is allowed near the telescope or in the dome at all. It’s sometimes a bit uncomfortable to coordinte with other maintenance but we can deal with it for a while. On tuesday, they have their last night, and then we are back to normal operation.

The segmented mirror of APE

If you want some more information on the E-ELT and APE, check out this public gallery from which I also took the pictures shown in this post.
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Hello,

I would just like to share with you a nice moment I had a couple of days ago. I have been working at Paranal for 3 1/2 years now, but so far have never seen the opening of the ATs.. These are the four auxiliary telescopes that we use as part of the VLTI. They are a bit more sensitive to the altitude of the sun, due to the fact that when they are open the sun shines directly onto the telescope, while the big domes can point away and shield the telescope inside. Hence, they are usually opened later and we don’t normally see it as we are already inside preparing the night. But the current group of VLTI astronomers needed special calibrations, and so the ATs were opend early enough for me to see it. I thought, I share these pictures with you.


Do you understand now, why we call them pacmans?
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Hello again,

I have been rather lazy in respect of blogging. I was busy in Santiago where I was working with a colleage from the ING in La Palma. We only had a the two weeks of his stay to analyse a lot of data and to start writing some publications. We did pretty well, I think, it was an exciting time. But to finish things off, I am still missing some input. Maybe if he reads this I don’t have to send an email for reminder

But now I am back in the desert. This time on Paranal and compared to La Silla this is the real desert. There is hardly anything alive around here, even after heavy rains, only a few small cacti might start getting green and have the one or other flower.

View from Cerro Paranal over the Atacama.

And it has been a busy start. Among others, I am responsible for the instrument ISAAC and the instrument is supposed to be moved to a different telescope. We had to evaluate the possible risks, the manpower needed, and make a plan how this move could be executed. Deadline was end of January, but we were a bit late, and only submitted the evaluation on the 1st. Now, we have to wait, what the decision will be and then the real work starts.

Yesterday, we had a small party up in the control room. Suzanna had her last night as a fellow here in Paranal, so we got a bit of sushi and some sandwiches to celebrate. No alcohol - that is strictly forbidden up here. It was still a nice party and a change from the everynight routine. So, good luck Suzanna, all the best and we will hopefully see you here again

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What I normally do when coming down from the observatory, especially from night shift, is having a loooooooong sleep. Like 24h and then I’m usually back to normal. Didn’t work out this time. For once, I have a visitor with whom I colaborate and who will be here only for two weeks. So, of course, we want to make the most of this time and started working immediately. Second, we observed a really cool star at La Silla who is doing lots of interesting things. We are still trying to figure out what exactly and how all the information we got fit together. It’s exciting! Third, the annual meeting of the Chilean Society of Astronomy (SOCHIAS) is happening right now and I still had to prepare my contribution when coming down from La Silla. So again, no time to sleep! Now, the conference has actually started it’s getting even worse. Even though a lot of astronomers have to work partly in night-time and we usually never change completely back to early morning hours, these conferences tend to start at 8 or 9 in the morning. The first day, we had to be here around 8ish to register; argh, two days ago, I still went to bed at this time. But that’s life, astronomer’s life anyway and you get used to it.

So, the conference itself is great! In my opinion the best of these national meetings is actually the “meeting” part. Of course, there are interesting talks and posters, but it’s a broad context so usually not much on your specific field of work. So, on these conferences, the coffee breaks are probably the more important events. Blame me for this sentence, but it’s true It’s in the coffee breaks, where people actually talk to each other and discuss new ideas. This is where connections are made, new colaborations founded, students have the chance to talk to scientists and get them interested, scholarships are discussed,… This is, what conferences are for. And of course, there is always a social event, like yesterday’s BBQ, which is also an excellent opportunity for people to meet. And believe it or now, most of the discussions on these parties are actually about astronomy in one way or another. Even while dancing, we just can’t let it go…

SOCHIAS conference dinner

Hello again,

I think, I should tell you a bit about La Silla, the observatory I am at during these days. It was the first observatory that ESO built in Chile. The more modern and bigger one is at Paranal where I usually work, and I will tell you about it later for sure. But it’s nice to be back on La Silla again; I did my fellowship here a few years ago. The whole mountain is full of little telscopes, as you might have seen on the picture of the previous post. Still, most of these telescopes are no longer operated. ESO itself keeps three telescopes running, and there are a couple of more operated by some European countries or institutes. Sometimes it’s a bit sad if you see all these dead telescopes especially if you remember the lively times before. Well, they still make for a nice scenery, I guess.

The 3.6-m telescope at La Silla

So now, as astronomers from ESO member states, we have access to three telescopes: the 2.2-m telescope with a wide field imager and a high resolution spectrograph, the 3.6-m telescope with HARPS, an extremely stable high resolution spectrograph which was built specifically to find planets, and has successfully done so several times, and the New Technology Telescope (NTT) at which I am observing tonight. The “New Technology” refers to the technology status of the 80s, when this telescope was built. It was the first ESO telescope where the main mirror was deformable and could always be put in optimum shape to get the best image quality for any position. This is a technique called “active optics” , which was pioneered by the NTT. Also the enclosure had a revolutionary design, as you can see on the picture below. Both, telescope and enclosure design where then adapted for the large telescopes at Paranal. the NTT, although it is getting old, is still a nice telescope to work with. And it has two good instruments, the infrared camera SOFI and EFOSC, the optical imager and spectrograph that I am using this time. I will tell you in some later posts about the science that I am working on, really cool stuff

The NTT at la Silla

But there are not only telescopes here. La Silla is situated at the southern edge of the Atacama desert, which is considered the driest desert on earth. However, since it’s only on the border, there is still some green around here, and every few years, when the winter was especially humid, we have the spectacular phenomenon of the ‘blooming desert’. Then you have little purple flowers all over the place and all the mountains around are covered in green grass. This happened also this year, that’s where the green patches come from that you can still see on the photos.

And we have animals here. Insects, scorpions and spiders, but also birds, viscachas (a kind of chinchillas), and a family of foxes is living here. The foxes are half tame because all the astronomers who come here want to feed them. I put a picture of a fox that I took the last time I have been here. Cute, isn’t it? I haven’t seen any foxes so far this time, I hope they are not gone, but maybe they have young ones at the moment and are thus more shy. Btw. did you know that foxes actually love grapes? I used to laugh at this story by Aesop ‘The fox and the grapes’ , but it is true. They are mad after grapes! It’s the only food they actually take out of your hands

The fox we called Federico.

Apart from these originally wild animals, there are also two dogs which belong to the observatory and sometimes a bunch of half-wild donkeys that belong to a family living a kind of nomade life close by in the desert. These donkeys are scary. Imagine driving in the middle of the night without lights (or only very dim light) because you don’t want to disturb the ongoing observations. Suddenly, you find yourself in the middle of a herd of donkeys. There have been some crashes already, the cars then get marked with a little donkey on the side (astronomers have a strange sense of humour, I guess).

For lovers of archeology, there are some petroglyphs found in the valley next to the telescopes. They make for a nice walk of 2-3h. I have done it several times, and it’s very pleasant as long as you take enough water with you.

Not too serious tools for the observation.

Of course, at La Silla, as at every observatory, there are not only astronomers working. In fact, the astronomers are a minority. There are technicians and engineers for software, mechanics, eletronics, …, people who handle the huge data transfer, cooks and people who clean the place, a paramedic, and people working in administration. And we have several possibilites to pass any leisure time. We have a gym, a table tennis, pool billiard, a library, even a small cinema and a good movie collection. And every now and then someone comes up with a crazy idea, like the new meteorolgy station or the already classic time server. You see, we have quite some fun here

And of course, we have a beautiful sky here. Watching the night sky, especially when it’s dark and no moon shining, is one of the best experiences you can imagine. It always reminds me of one of Walt Whitmans poems :

When I heard the learn’d astronomer;
When the proofs, the figures, were ranged in columns before me;
When I was shown the charts and the diagrams, to add, divide, and measure them;
When I, sitting, heard the astronomer, where he lectured with much applause in the lecture-room,
How soon, unaccountable, I became tired and sick;
Till rising and gliding out, I wander’d off by myself,
In the mystical moist night-air, and from time to time,
Look’d up in perfect silence at the stars.

Well, what can I say as final words: La Silla is a magic place and I am always happy to be back!
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I am on La Silla observatory, doing duty for ESO. We usually do either Christmas or New Year’s eve and I’m up for the change of year this time. We had a really bizarre party as everybody was observing, sitting in front of the computer. But like 5 min before midnight, we all got together, opened a bottle of wine and kind of celebrated. By now, however, everyone is back to work. The idea is to meet for sunrise (after the night’s work) for a small celebration on the platform of the 3.6m telescope. This is a nice place; it’s the highest point of the observatory and you have a wonderful view not only of the rising sun.

This is it for the moment, tomorrow (well, today), I will do my first observations of 2009, let’s hope the weather holds!

I have added a picture of La Silla that I took this afternoon, so you have an idea how it looks like here.

La Silla Observatory as seen from the 3.6-m telescope