What is CCD Bakeout?

You may have noticed yesterday that the picture showing “How the Solar System Appears Today”  had the picture of the Sun showing something called CCD Bakeout?

What is CCD Bakeout?

The Solar & Heliospheric Observatory spacecraft was launched in 1995 and placed in a position about 1.5 million kilometres from Earth in a spot where it is always between the Earth and the Sun. In this way, the spacecraft can take pictures of the Sun without concerns of weather or timezones and constantly monitor what is happening on the Sun.

The CCD camera on SOHO is much like that of your digital camera. If you try to take a picture with your camera when there is not enough light around, you will see snow in the image viewer and normally a message saying under exposed. This is the same with the CCD on SOHO.

At times the CCD camera out in the -67 degree temperatures of space may begin to suffer from the “snow” effect as a result of water vapour condensing on the CCD.

To avoid this ,every 3 months for a period of anything up to a week or even a month , the CCD camera is warmed up by small heaters in the camera to a temperature of +16 degrees to ward off the water vapour.  During this time the CCD images are not available after the heaters are turned on. When the heaters are turned off , the images are available again a day or two later.

We looked further into this and so far this year , the heaters have been turned on 3 times so far this year.

January 27……   April 26  and  20 July.

The heaters were only required to be on for a period of 8 days this time so yesterday the heaters were turned off and we should have images coming through probably tomorrow.

CCD Bakeout

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~ by sydneystargazers on July 30, 2010.

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