End of 2018 I visited the new Cherenkov Telescope on La Palma. Actually I planned to write a long article about this visit - but as it happens sometimes, other things are more important... I decided to skip this article since now there is sufficient information out there about this telescope. However, I think the images I took for this article are still worth to see and give an impression from the observation site on the Roque de Los Muchachos on La Palma. The following two links provide more information about the CTA on La Palma:
Recently Dark Sky Travels Magazine contacted me and asked if they could publish one of my blog articles in their magazine. The article describes how one can use DeepSkyStacker to stack conventional DSLR camera RGB frames. Of course I didn't say no and in the end it just happened and I saw my article on page 42/43 in Issue 4 of the DarkSkyTravels magazine!
I am very happy about that opportunity and the chance to share my experience this way.
Thanks and clear skies!
Long story short - I was looking for a way to detect more or less reliably if a user selected a region which contains a star. I wanted to be able to clearly distinguish between the following two images:
After a long journey I finally ended up with the following working solution based on the CImg library:
CImg <uint16_t> image;
double q = image.variance(0) / image.variance_noise(0);
double qClip = (q > 1 ? q : 1);
double snr = std::sqrt(qClip - 1);
For the two images above the code gives the following results:
~/snr$ ./snr no_star.fits
~snr$ ./snr test_star.fits
For many people this is where the journey ends. But for some of you it may just begin 🙂 Follow me into the rabbit hole and find out why the solution shown above actually works…
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