Raspberry PI Planetary Photrography





I have always been fascinated by space, be it planets, galaxies and everything in between. During the summer, I could often see two bright spots in the sky, Jupiter and Saturn, yet I never really pursued exploring the night sky by myself. While going to work, I found on the side of the road a somewhat broken, cheap kid’s telescope that somebody wanted to get rid of and decided to take it with me. Observations with it was very hard, because of the lack of a finder scope, the cheap build quality, and poor optics. I tried observing both Jupiter and Saturn, and while the latter was just a yellowish spot, I was able to discern the Galilean moons while observing the former.

I really enjoyed the experience and wanted to observe more. Being in a rather light polluted area, I can only observe the moon and planets and with this cheap telescope I had quickly looked at everything that I could. I always wanted to see Saturn's rings with my own eyes (I know its cliché, but it is what it is) so I started looking for a better telescope. Someone I know owns a telescope and was kind enough to let me borrow it. It was not in perfect condition, but good enough for a beginner. I was really happy with the new scope; I could see the rings of Saturn and a much better view of Jupiter and its moons. I now wanted to capture what I saw in the scope with a camera, so I started researching astrophotography.

Most of what I found was galaxy and deep sky imaging, which turns out to be a very technical skill, using a bunch of expensive tools and software. Yet, when narrowing my research to planets, a bunch of people could get pretty good images using webcams. The only camera I could mount on the telescope at the time was a Raspberry PI infrared camera(PI NOIR). To test the rig, I made a cardboard mount for the camera and the PI. The "mount" worked better than I had expected, so I kept it and and installed a web interface to access the Pi. I could now see through the telescope and control the camera with a laptop.

Telescope and laptop setup. RPI mount.




While doing my research, I learned about stacking pictures, which is a commonly used technique in astrophotography, to reduce atmospheric perturbations and noise which degrades picture quality. Although one of the axis of the telescope's mount was not working properly, I was able to follow the planet by hand while taking a video with the camera. I extracted all the frames from the video as images to stack them. I found this really helpful tutorial, which I followed closely:





Here are the results. The video is two excerpts of the long video from which I extracted the frames. The first image is a raw frame, while the two last images are stacked images. This shows how important the stacking process is to improve image quality:

Raw frame of Saturn.
Stacked result of Saturn. Stacked result of Jupiter.

Obviously, because this is and infrared camera, the pictures are not the same colors that we see with our eyes, and I tried color correcting them(with disappointing results, I must say):

Color corrected result of Saturn. Color corrected result of Jupiter.

Although the images are far from what experience astrophotographers can do, this first astrophotography experience was really fun and made me want to continue exploring this hobby. I have bought a DSLR camera since then and will see if I can get good night sky pictures soon.

FM






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