GTC Observatory
Roque de los Muchachos
La Palma, Canary Islands
Overnight, the hard working compressor finally got the temperature of the infrared detector down to where it needs to be, about 444 degrees below zero. A meeting is held in the morning with the observatory staff to coordinate the many activities that need to occur, some simultaneously, to get CanariCam ready for use on the GTC (Grantecan) telescope. Michiel van der Hoeven, Chief of Operations at the observatory, tells us that the staff stands ready to help get the instrument commissioned.
Now a new enemy is raising its ugly head - bad weather, the bane of every astronomer's existence. A storm is predicted to come through Wednesday, just when it is hoped that the University of Florida team can begin making initial observations. Nothing to do about that but wait and see. Astronomers tell stories of waiting months to get one precious night on a large telescope for a project, only to have that be the one night when it decides to rain, ruining the observations and requiring another multi-month wait for another try.
The observatory staff is already putting on the adaptor plate on the telescope, which will allow CanariCam to be fitted to the telescope's focus. The thick black steel plate, specially designed for CanariCam, weighs over a ton and takes three workers and a crane to get it up to the focus and bolted to the telescope. The segmented mirror (36 separate mirrors), largest in the world, sits on its side in the dome, waiting to be let loose on the skies.
In a room under the dome, six extra mirrors are kept in storage, ready to act as replacements as needed. UF astronomer Chris Packham gives us an up close look at these individual mirrors. Their undersides are covered with intricate motors and pulleys which can slightly bend the shapes of the mirror surfaces, compensating for minor errors and seeing conditions.
Suddenly, at about 12:30, the steady drone of the compressor ceases and everything gets strangely quiet in the lab. The compressor has quit working and the internal temperatures are starting to climb back up. Everyone stops what they're doing, and an intense session of troubleshooting begins. Gregg Bennett, the team engineer, takes the cover off. The compressor tank has overheated. A short? A bad solenoid switch? A helium leak? A replacement compressor is wheeled in, but the detector temperature is already back up to minus 425 degrees F, extremely cold but much too hot for infrared work. A few tweaks later and the old compressor kicks back on. The temperature immediately drops back down to comfortable levels.
Except for the activities of the CanariCam team and staff, the cavernous dome is empty and quiet. One floor below, the control room mainly consists of a maze of computer screens. Here, the dome can be opened and rotated, and the telescope pointed with extreme accuracy. Some of the more precise guiding aspects of the telescope are still being modified, but it is hoped that both the telescope and CanariCam will soon demonstrate that they make a fine pair. That is, if the weather holds up!
Terry Smiljanich
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I recall one night at Lick Observatory in about 1963 when George Wallerstein was scheduled to observe with the 120" coude spectrograph an even which happened only about every decade (I forget the details but must have been an eclipsing binary). Thus was born the term "Wallerstein Weather". Total wipeout.
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