Truth About Raw Data and Images

There is already a bunch of people that knows a lot about astrophotography image processing or simply image processing/postprocessing in photoshop/lightroom/darkroom/PAINT.

However true images from ccd cameras operating on telescopes are completely different level than a normal camera - starting that they usually operate at -30/-40˚C or lower depending on the observatory and it is connected to the desktop computer for data storage/dumping.
That's it... everything is operated by particular software (these can vary from observatory to observatory), basically, all settings pretty much very depending on the telescope specifics and objects you want to observe/detect,

Anyways, I just stumbled upon this nice article about raw data on astronomy blog https://skyandtelescope.org and if anyone is interested it is a quick read and somewhat informative. :)

Anyways in order for this post not to be just a simple copy paste and several sentences I have already mentioned so many times on my blog (but apparently they find their way back). Here are two images which are pretty much processed taken in different filters: [S II] and Hα line.

• [S II] - means forbidden (emission) line of ionized sulphur Read more on forbidden lines.
• Hα -is specific balmer line - [Read more on H-alpha](https://en.wikipedia.org/wiki/H-alpha line).

Now in order to explain all these would take me a whole post to do it. What you need to know is that these lines have EXACT energy (quantified - if you want to go that way) which means they always appear on the same wavelength (once we apply a correction for Doppler effect). But if there are interested folks I think I could get my hands dirty and type some stuff up. :)

Anyways this is what a spectrum with emission lines looks like:

example from optical fitting tool - source with github link
Why are they important they tell us a lot of stuff about the environment, temperature, indicate something etc. For example, we use some these lines (sulphur H alpha and Nitrogen and oxygen) to hunt for supernova remnants in optical - which are then confirmed with radio observations.

How do we do that - simply by checking ratios between Sulphur line and Halpha line. If it is higher than 0.4 it is a Supernova Remnant if it is not then it is H II region (just a normal bubble of hot gas - reaching up to 10 thousand Kelvins (or celsius) if you like it more. 270˙ is not gonna change much).

Anyways another post for itself - I think I'm rediscovering my writing mojo here. :)

Here are the [SII] and Halpha images with subtracted continuum emission (gaussian-like blue line on the figure above).

Do you see any differene in these images?
Or if you would like some colorized version (from wikimedia - not my dataset)

Fireworks Galaxy - source:wikimedia

You can also check out some other fancy NASA images for fireworks galaxy - copyrights and all that stuff for sharing. :)

If you are new to my blog or if you have forgotten - feel free to ask anything or if you are interested in spectroscopy/forbidden lines/ continuum vs line emission/ supernova remnant hunt or any question that seems fitting to you regarding this topic or any other in astronomy let me know. And we'll see what we can do to shed some light cause I like to be THE lighthouse of knowledge. :) ::P

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