Wednesday, July 29, 2009

Daytime Open Dome

It isn't often that the dome of the 200-inch telescope is open in the daytime. Normally, the dome is sealed up tight so that we can maintain nighttime temperature inside the dome. This keeps the telescope and its instrumentation at the temperature it will be used during the night.

Once in a while, if there has been a big swing in temperature, we need to open in the day to allow for the telescope and dome air to equalize in temperature with the outside air.

Today, we opened the dome to allow our crew to perform maintenance on the rails that the dome shutters ride on.

For me that meant that I had another opportunity to take photos of the Hale Telescope in lighting that is different from what is normally found in the dome. Below are some of my favorite photos from today. Remember you can click on them to enlarge the view.

Here is the view from the catwalk south of the telescope with the dome fully open and the shutters pointed just east of north:

This image is from the catwalk, positioned just south of west of the telescope, with shutters fully open:

For scale, note the person walking across the dome floor. He is a little to the left of the telescope and a bit further away.

It seems that my favorite lighting is with the shutter only partially open. That way there is some natural light, but the lights within the dome add some color to the view. For this photo I was again on the catwalk, but directly southwest of the telescope. As you can see the shutter is just cracked open a little bit:

This photo was taken from the east side of the telescope, directly above the visitors' gallery. It was also taken with the dome just barely open:

This shot was taken from the dome floor and is perhaps my favorite from this morning. The shutter is cracked open a little bit giving a nice mix of natural and artificial lighting:

In this shot you can see what looks like a human figure on the observing floor. That is actually one of the heated electric flight suits that the astronomers used to wear when riding in prime focus. We have it on display for our many visitors.

Finally, the experience would not be complete without showing you the view from outside the dome. This was taken along the visitors path that leads up to the dome:

The time to perform the maintenance was limited because we do not allow direct sunlight to fall onto the telescope. When the Sun is high enough in the sky it is time to close the dome. Because of that the work is not yet finished.

We do expect to have the dome open again on Thursday, July 30 from about 8 to 10 a.m. PDT. It might make for a nice time to plan a visit or to look in via our webcam.

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