As some of you know, I’m a big astronomy buff and have been into astrophotography ever since I was a kid. Here is one of my better efforts, The Andromeda Galaxy. It was actually published in Sky and Telescope a couple of years ago and they even gave me 50 bucks! I don’t think I will quit my day job though.
Anyway, because of my astrophotography friend Dave, I was able to get a visit to the Las Campanas Observatory located in the Atacama desert about 100 miles northeast of La Serena, Chile. They don’t do public visits here so it was a very big deal for me to be able to get into the site. My timing was very lucky because it just so happened that a buddy of Dave’s had an observing run coming up and he agreed show me around the site. I went up through the Atacama Desert to get to the observatory.
This is not your run of the mill fork in the road. One goes to Las Campanas, and the other goes the La Silla European Southern Observatory.
The tops of those peaks in the distance is where the observatory is located.
I never thought that one of the premier observatories in the world would be down a dirt road.
The ride to Las Campanas was quite a scenic ride.
Upon arrival, I was treated with a view of the twin 6.5 meter Magellan Telescopes. 6.5 meters is the diameter of the primary mirror of the telescope. That’s a pretty big scope, and there are two of them.
The three other domes in the distance contain a 100 inch scope, a 40 inch scope, and the small dome in the middle of the other two is the Polish Telescope. No kidding. I really wanted to see what a Polish Telescope looked like, but I never went in the building. I wanted to ask the astronomers if the Polish Telescope actually made stuff look smaller, but somehow I think my incredibly stupid joke wouldn’t have produced even a chuckle.
This is the lodge where the visiting astronomers are housed. I had a room here as well.
After I got settled in my room I was give the nickel tour by astronomers Andy and John, who work for the Carnegie Institute out of Southern California.
This is the new FourStar imaging instrument. FourStar is a near infrared imaging instrument that is undergoing testing and will get bolted on the Baade 6.5 meter scope in January 2011.
That’s a big camera. It contains a 4 detector array, each sensor being 2048 X 2048 pixels at a cost of……….$25,000 per chip! That’s $100,000 worth of CCD’s at the business end of this camera, wow! The camera and optics are housed in a vacuum, and the detector array is cooled with liquid Nitrogen to 77 degrees Kelvin, about -320 degrees Fahrenheit, or -200 degrees Celsius.
Cooling the chips to these extreme temperatures minimizes dark current on the chip to nearly zero. In fact, if you try and calibrate your images by subtracting a dark frame, it will actually add noise to your image. In addition, these near infrared sensors are of course very sensitive to heat, so the arrays and the optics need to be cooled dramatically.
At this point the camera is hooked up to the liquid Nitrogen and is in the process of being cooled. It takes 7 days to cool the sensors to 77 K, and takes 5 days to warm them back up when work needs to be done on the instrument.
Also on site is a small solar telescope, which is operated remotely, over the internet.
This is the dome that houses the 100 inch du Pont telescope.
The grain elevator like thing in the foreground of the below photo is what is called a “seeing monitor.” It evaluates what astronomers call atmospheric seeing. Seeing basically has to do with the steadiness of the atmosphere at the location of the telescope. If the stars a twinkling rapidly, the seeing is bad whereas if the stars hardly twinkle at all, the seeing is good. Dark skies are important, but the quality of the seeing (steadiness of the local air mass) is equally important. If the atmosphere is turbulent, the resolution of objects will be poor. But a steady atmosphere will yield images of much higher resolution, which is very important for observations. For example, the Hubble Space Telescope produces such stunning images because it does not have to look through an atmosphere. Generally speaking, good seeing is found at locations on a mountain with the airflow coming off of an ocean. That’s why many professional observatories are found on islands or mountain tops near the ocean.
The Las Campanas site is said to have the most consistent and best seeing of any observatory in the world. Because of this, the GMT, or Giant Magellan Telescope, a 24 meter telescope will be erected at Las Campanas and will be operational by 2018.
During the imaging run that night, we had seeing as good as .4 arc seconds, which is very, very impressive.
OK, so lets go up and have a look at one of the the 6.5 meter Magellan telescopes.
This is the inside of the dome of the Baade 6.5 meter scope. You cant look through these telescopes, they are strictly for imaging as all astronomical research these days is done by CCD imaging. However, I believe that the 100 inch du Pont scope (an old school scope) has what they call a Coudé focus, which means that you can put an eyepiece in and look through it when its not being used for imaging.
Here I am standing underneath the primary mirror to give you a better idea of scale. This is a big telescope.
The building between the two domes houses other cameras, or instruments. This is another camera, cooled with liquid nitrogen of course. However it is not a infrared sensor, so it only gets cooled to about -150 degrees C
Also in the building is this contraption. This is a mirror washer and aluminizer. The 6.5 meter primary mirrors of these telescopes are very expensive and require maintenance once a year. Instead of the risk and expense to send the mirrors to another place for cleaning and recoating, they do it all right in house, literally. Each primary mirror will be washed once a year, then every second year it gets a fresh reflective coating.
This is the brain of the operation. There are two separate computer systems for the scope. The Mac system on the left controls the camera while the system on the right controls the telescope, dome and guide camera. Both systems are Linux based. I was told that they are in the process of converting everything over to the Apple computers because they said that they have less problems with the Apple hardware. I’m not a computer geek so much of the computer speak was lost on me. Suffice it to say that they use a lot of computer power to run this scope.
This is the telescope control room. The guy on the left is the telescope operator. The guy on the right is an astronomer. So this is how it works. The astronomer controls the camera with the computer system in front of him. In turn, he tells the telescope operator where to point the telescope for each target. So, the operator drives the telescope around with instructions from the astronomer, and the astronomer takes images with the camera. I was stunned at the pointing accuracy of this big scope. The astronomer was asking for movements as small as 0.5 arc seconds and I found it amazing that such a large telescope could be pointed so accurately. John, the astronomer was collecting images for analyzing the redshifts of low surface brightness galaxies. Which in layman’s terms means that he studying very dim and very distant galaxies and trying to figure out how far away they are. Most of his targets were 25th to 27th magnitude objects, which means they are very dim. One other thing to note is that for the first target, the guide star was 18th magnitude and the guide exposure was only 2 seconds long. Very impressive light gathering capability and guide camera sensitivity.
Sunset at the domes.
Looking out over the Atacama desert.
Just before sunset, the telescope operator and the astronomer settle in for a night of work.
The domes are opened early to allow the optics to cool to outside ambient temperature.
At night during the imaging runs there is not much to do but sit around, BS, eat empanadas and watch the data come in.
Spectacular skies at the Las Campanas Observatory.
It was a fantastic experience to visit this observatory and to be able to sit in on a night of imaging with the professional astronomers. Thanks to my astronomer friends Dave and John from California who were able to get me into the site, this visit has been one of the highlights of my trip.
The next day I headed down the mountain…….
………and back to La Serena. Notice my new touring windscreen? 250 bucks in Chile, ouch.
We now return you to your regularly scheduled not as geeky ride report.
Saludos.