As our last night on the mountain draws to an end, we’re fighting strong winds and occasional technical glitches in the camera control system (solution : turn off, turn back on again) to get images of some of the most useful galaxies we’ve seen yet. One is a more distant version of Bill’s personal touchstone, NGC 3314. I hope you’ve enjoyed the blogs we’ve posted over the last five nights – there will be more to come as the work on all of this fabulous data continues However, you’d be forgiven if you failed to work out from the posts what it is that has been keeping us, or rather Anna in particular, so busy. Read More…

The whole point of the observing run is to try and understand dust in external galaxies, but we’ve already encountered dust in the Milky Way, and producing spectacular sunsets and tonight I observed another manifestation of dust – the zodiacal light, subject of Brian May’s thesis.

You can see it in this picture from the all sky camera, as the glow over on the right.

The glow is from light reflected off dust in the plane of the solar system, the left overs from the process that produced the planets. This was a particularly good display, reaching almost up to the zenith. It’s the best display I’ve ever seen, having dashed out into the wind. The wind is the major feature of tonight’s observing so far, being strong enough to force us to point the telescope away from it, and loud enough to cause the dome to creak and moan. All a little disturbing, but apart from that conditions seem good.

The second Galaxy Zoo paper, which introduces the survey and provides details of our initial data analysis, is now available online via astro-ph.

I look forward to hearing your comments….

I’m proud to announce the winners of the first Galaxy Zoo Caption competition. Bill, Anna and I decided the winner by printing out all the entries and then standing around pointing at them. All the entries were appreciated in getting us through the wee small hours of the mornings, but there can only be, in this case, two winners: pluk (“Bill: “No Chris, it’s not your turn yet, Anna had a match”) and Curtis (“After the witnesses identified the suspects from the photo lineup, they were quickly arrested.”).If both would contact me via the forum or email (chrislintott AT cantab.net) then we’ll get your prizes to you.

Colour in astronomy is a difficult and often controversial topic. Rather than just lump all the photons together, we like to use separate filters which allow a standard set of wavelengths through; that means that when I talk about a ‘blue’ image, then I will certainly be talking about the same ‘blue’ as anyone else. Each colour encodes information; blue represents young stars, red old stars or emission from dust. This is all very well, but the problems start when we try to produce colour images. Which filters do we use? No camera has the same response as the human eye, so this can be a controversial question. The Galaxy Zoo images are based on three of the Sloan filters – blue is blue, but red is green and infrared is red. That’s why the Voorwerp appeared as a blue blob even though it’s really green.

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I’ve already written a little about the WIYN telescope itself, but equally revolutionary at the time was its enclosure. Domes used to be designed to keep as much of the external world out as possible, isolating the telescope from the turbulent air outside; the high point of this design might be represented by the Kitt Peak 4-m, standing high above the ground in an effort to get above the turbulence.

If you look closely at the dome, though, you might spot a series of small shutters. These were added afterwards, once it had been realised that opening your telescope to the air made a lot of sense; a smooth air flow across the mirror is easier to establish than completely still air beneath an open dome slit, and doesn’t interfere with the quality of astronomical images. That’s the thinking behind the initially shocking design of the WIYN ‘dome’:

The large holes in the side allow the wind to pass through, creating stable conditions inside the dome. (That’s the theory; last night we had to shut the panels because the wind was strong enough to noticeably shake the telescope.) There are other advantages too, of course; panels of steel are cheaper than beautifully shaped domes. It may not be aesthetically as pleasing, but it works.

Despite patchy cloud, we’re just about ready to start observing on night 4. Probably thanks to that low cloud, it was a spectacular sunset over the neighbouring mountains.

 At a first glance the seeing looks reasonable, and we’ve already selected our first galaxy.The main aim for tonight is to fill in our collection of elliptical/spiral pairs; we’ve noticed we’ve done almost twice as many spiral/spiral pairs and we’d like to have an even distribution. I think this is just because spiral/spiral pairs look nicer, and in the early hours of the morning a nice image to share on the blog is a strong incentive during the cut and thrust of target selection. More shortly. 

Tonight has been much less straightforward than previous nights; we’ve dealt with a succession of computer glitches in the camera controls, for starters. Nothing serious, and nothing that our telescope operator hasn’t been able to resolve fairly rapidly, but still enough to eat up some time. For most of the middle of the night, the seeing was poorer than we’ve seen on this run so far, and a strong wind forced us to shut the slats that normally allow steady airflow across the dome. However, there have been some highlights too; several of the images have been stunning, and we’re now rushing to get ahead of twilight as the conditions are the best they’ve been. For me personally, though, the highlight was stepping outside to observe dust much nearer to home. Just outside the door a few hours ago was the tail of Scorpius and its neighbouring constellation Sagittarius. Neither gets very high from home (parts of Scorpius don’t even rise), but there they were. To the left was Jupiter, shining more brilliantly than anything else in the sky – apart from the last quarter Moon, rising and shining red as it passed through the dust hanging above the desert floor. Looking back to Scorpius, the Milky Way was clearly visible despite the presence of the Moon (Nature’s light pollution). In front of the stars, the dark dust clouds that block our view of the Galaxy, and in this case a reminder to get back inside and get back to work.  

We’ll find a Kitt Peak related prize for whoever makes us laugh the most… 

Anyone keeping an eye on the blog should know that we’re looking at overlapping galaxies to try and understand the nature and distribution of dust in galaxies. Prompted by very pertinent questions from Barbara, our guest for the night in the control room, it’s suddenly occurred to me that we haven’t ever told you why we care about dust in galaxies.  Read More…