March 13, 2007

Sic Transit Gloria



This glorious movie was obtained during a CCD calibration for the STEREO mission. The pitch black disk of the moon crossing in front of the sun from a million miles away is used to find the baseline of the instrument, which is designed to observe the sun. Astronomical photos of the sun always end up being better than I expect them to be, and since this a mere calibration, I expect my expectations to be surpassed.

3 comments:

Fresh from the Source said...

Wow. I was thrilled to watch this video of the moon crossing in front of the sun. I'm not an astronomer so this question may seem silly, but I noticed the light 'particles' flying off of the sun into space; not the corona around the sun. What are those particles? I wondered if they may even just be part of the resolution of the photography. Thanks.

(Ryan) M said...

The particles are the result of the "dark current" in the CCD camera. Any time you have a camera of this type, stray electrons will leak through the circuits that produce the image at a certain rate and make it appear that the camera is seeing flicks of light. Each one of those flashing particles is actually just an electron in the CCD. You can see that if you look at the disk of the moon you see them as well, so it isn't an astronomical phenomenon. Measuring how much of this stray signal you see when the image ought to be completely back is how you find the baseline for the camera. And that is, in fact, what they were doing when they shot this video, using the disk of the moon as their perfectly dark area.

Fresh from the Source said...

Thank you. Even knowing that I am seeing stray electrons on the image is interesting. Sort of micro and macro in one shot.