Looking at Jupiter's hot body (emissions)

Hello there, this weekend I am struggling against a migraine, so this post will have to be short; and whilst I have a window of opportunity given to me by analgesics!

So I am now 3 months and 13 days into my new career which started on the conveniently-to-remember date; 10-10-10. 

In my present work, I have been 'cleaning' spectral images of Jupiter taken in Aug 2010 from the NASA infra-red telescope facility in Hawai'i. Note that I stated 'spectral images' and not simply 'images', the difference in this case is that a spectral image is one which shows the different amounts of light intensity at different wavelengths, e.g. Red light has an intensity of 50, blue light has an intensity of 100. With this information you can find the temperature of the body that has emitted it. So my work is to find the temperature of Jupiter's upper atmosphere by analysing the spectral data of it. I will talk more about spectral images in the future, when they are cleaned and ready. For now, below shows the difference:

Jupiter; a 'normal' image. Using it's Infra-red emissions.
Note the line in the middle is the 'spectrograph'

Jupiter; a spectral image. Using Infra-red emissions.
This is from the 'spectrograph' shown in the 'normal' image, each line from left to right in this image represents a different intensity of emission from Jupiter at different wavelengths, but all on the same one line seen on the 'normal' image. I'll go over this again in detail some day...!

So what do I mean by cleaning? Intuitively, cleaning these images means getting rid of dirt, in this case the dirt is in the form of sky emissions, cosmic rays and 'background noise'. I will talk about these below:

• Sky emission? The telescope pointed at Jupiter to record it in the infra-red (IR) region, unfortunately, the telescope is peering through the Earth's atmospheric medium, which has it's own IR emissions - so the telescope takes a picture of Jupiter, denoted A and then a picture of our own sky, denoted B and by subtracting B from A in a process called 'A B subtraction' the unwanted emissions are cleaned away.
• Cosmic Rays? These are essentially high energy particles from space, such as protons and electrons, when one of these bad boys enters the CCD lens of the camera behind the telescope, a bright flash is recorded - which looks not disimilar to a star.
• Other background noise includes IR emission by the equipment on the telescope, this is mostly removed by super-cooling  the equipment with liquid nitrogen, so that it does not radiate. The CCD lens on the camera is never 100% accurate either, some parts of the lens will record better than others, to get around this a process of flat-fielding is performed. Flat-fielding involves perfectly illuminating the CCD lens and taking an image, then it can be seen which bits aren't picking up the light as well as others. This becomes rather a complicated procedure so I won't go into it now, but it is worth mentioning that this is one of the most difficult noises to get rid of, e.g. if a pixel isn't picking up anything at all, information is permanently lost and you can never know what was there!

So maybe this wasn't as short as I thought it'd be! Thanks for reading, sorry if it is confusing - feel free to ask questions or correct me if I'm wrong ;-)

James