Tag Archive | La Silla

Leaving La Silla

Our pea hunting observing run is over and, as you will have gathered from previous posts, it has gone very well. We travelled back from La Silla to Santiago last night, for another brief stay at the ESO Guesthouse. Now I’m about to get on the plane back to the UK.

We are thrilled with how well the run has gone. I’ve done a rough analysis of the data already and we’ve already started drafting the paper presenting the results! I’ll do a more careful analysis once I get back to the office, but early indications are that we’ve got a nice collection of higher redshift objects that are very similar to the fascinating SDSS Peas that were discovered on the Galaxy Zoo forum, and an almost perfect technique for finding more! I’ll keep you posted as our work progresses.

Technical problems

The Chilean Pea hunt continues…

You may have noticed the Galaxy Zoo blog was down over the weekend. Well, it wasn’t the only one to be experiencing technical difficulties. On Sunday night we unfortunately lost four hours of observing time to technical gremlins. First we tried to use a new filter, which resulted in a nice 10 minute exposure of nothing. After a trip to the telescope to look around inside the instrument, the support staff worked out the problem: the filter was mislabelled on the computer. With that figured out, we changed to the correct filter and carried on – only to be stopped in our tracks again a couple of hours later by the whole telescope control system crashing! This time it took three hours of methodical troubleshooting to fix the problem, apparently some problem with a power lead. By then the night was almost over.

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Peas please me

Well, at the start of the night we were a bit nervous that none of our objects would turn out to be Peas. Fortunately, by the end of the night our quick looks at the data indicate that four of the seven i-Pea candidates that we managed to observe are emission line objects at the redshift we expected our selection to give, i.e. they are Peas! That’s about as good a success rate as we dared hope for.

The night hasn’t been without its difficulties. The seeing (how blurry the atmosphere makes our images) wasn’t great for most of the night, and it has turned out to be hard to actually find our targets because they are so faint. Those issues combined meant that we didn’t get through as many candidates as we hoped for, but we are still happy with the collection we got.

Right now, time for a quick breakfast then some sleep before trying to net some more Peas tomorrow night.

Here we go…

The continuing adventures of the Pea hunting trip to Chile

We’ve spent the afternoon finalising our target selection, preparing our observing strategy, and taking calibrations. The sun has now set and we’re already pointing in the right direction for our first target. In a few minutes time we will start our observations. We begin with a standard star, which will be used to calibrate the spectra of our main targets. The we are on to our first Pea candidate.

The SDSS Peas that Carrie studied were green in the SDSS colour images because they were bright in the r-band, actually the red region of the visible spectrum. On this occasion we are looking for similar object that are a bit further away, so we expect them to be very bright in the i-band (further into the red) ar the z-band (on the border between red and the near infrared). Tonight we are observing the i-bright objects, and hopefully we will get through about a dozen of them. The weather looks good, so fingers crossed.

Anyway, better concentrate on the observing.

On the mountain

The continuing adventures of the Pea hunting trip to Chile

An hour’s flight from Santiago to La Serena, followed by a 2 hour drive, and we arrived at La Silla in time for a tasty lunch (notable lack of peas, though). We then had a meeting with our support astronomer to check our plans for the upcoming observing run and make sure we had filled in all the necessary forms. He also kindly gave us a tour of the three biggest telescopes, including the NTT which we will be using. I’ve been here a couple of times before, but always using the NTT, so it was nice to see the other main telescopes, and get some great views from their dome catwalks.

View of the La Silla landscape from my room

View of the La Silla landscape from my room

The landscape around La Silla is red, arid and lumpy. Dry red soil strewn with small rocks, covering many hills of different sizes which appear to be piled on top of one another to form larger peaks. Although this is the edge of a desert, the landscape is dotted by small bushes, though many look more like collections of twigs than living plants.

La Silla observatory was set up in the early Sixties. Like other sites from the same era, such as La Palma, Kitt Peak and Siding Spring, it sports a collection of telescope enclosures of various shapes and sizes. Although the traditional dome is most common, it seems the discerning enclosure has an element of squareness, the degree of which varies with construction date like a fashion.

The telescopes here have apertures varying from half a metre to 3.6 metres. Although the atmospheric conditions at La Silla are very good, they weren’t considered exceptional enough to site the latest generation of 8 metre telescopes here. Instead ESO chose to develop a new observatory at Paranal. When you’re pushing technological and scientific limits, and spending the amount of money that requires, you need to be very careful choosing your site to maximise the quantity and quality of observations that are possible. As science has advanced and typical astronomical observations have become more challenging, the numerous small telescopes around the world are being used less and less. In fact, most of the domes on La Silla are either empty or contain telescopes that are no longer in routine service.

Visiting astronomers usually arrive on the mountain at least one night before their observations begin, to prepare final details and adjust to nocturnal working. We actually have two full days and nights here before we start using the telescope. That will give us plenty of time to review and refine our initial list of targets, although we will certainly still need to adapt our plans once we start taking data. We’ve now got our list of high priority targets organised, and tomorrow we’ll decide upon other interesting objects that it would be useful to observe, if everything else is going well.

Pea Hunting preamble

Greetings from the ESO Guest House, in Santiago de Chile! As I described in a blog post) a while ago, I am here on a mission to hunt for more distant counterparts to the ‘Peas’) which were first identified by Galaxy Zoo participants.

This is the first Galaxy Zoo initiated observing project to use an ESO telescope, so I thought I would take the opportunity to give you a bit more of an insight in to an ESO observing trip. ESO is the European Southern Observatory, which operates observatories in Chile in order to provide European astronomers with access to the Southern sky. These are among the most technologically advanced and scientifically productive observatories in the world. ESO’s premier facility is the, imaginatively named, Very Large Telescope (VLT), located at Paranal observatory in the middle of the Atacama desert. The VLT actually comprises four massive telescopes which are usually used separately, although their light can be combined for special observations.

For our observations we don’t need quite so much light-collecting power, so will be using the smaller, but still very capable, New Technology Telescope (NTT) at La Silla observatory, also in the Atacama, but in its slightly more hospitable Southern outskirts.

ESO Guesthouse

The ESO Guesthouse

I, and my observing colleague Seb Foucaud, arrived in Santiago earlier today after long journeys from the UK and Taiwan, respectively. ESO is an extremely well organised operation and really looks after visiting astronomers. We were met at the airport by an ESO representative and driven to the Guest House in the affluent Las Condes suburb of Santiago. The Guest House is renowned for its hospitality, friendly staff, good food and the traditional Pisco Sour cocktail before dinner. Most visiting astronomers stay here for one night before and after their observing run. Tomorrow morning we fly to North to La Serena and then drive to La Silla observatory to begin the preparations for our run, which starts on Thursday night. Right now I’d better get some much needed sleep. I’ll give you an update when we get to the observatory.