First stacked astrofoto

Orion belt and nebula

On saturday morning I woke up pretty early and when boiling water for tea, I saw quite a lot of stars from our south facing kitchen window. I took the chance to take some pictures of Orion, which was still high enough.

At that morning I was not able to take too many picture, there was a plane crossing on two images and then clouds came up, that’s why I have more darks than lights.

  • 15 lights: 100mm, f/6.3, 6" ISO 3200
  • 20 darks: 100mm, f/6.3, 6" ISO 3200 (with cap)
  • 10 flats: 100mm, f/6.3, 1/60" ISO 200
  • 10 biases 100mm, f/6.3, 1/60" ISO 200 (with cap)

For stacking, I used the OpenSource software Siril, following their tutorial. It was not immediately obvious to me what are flats and biases. It is better explained in “a brief guide to calibration frames”. So next time I will take biases with 1/4000".

I bought a minitrack. However on my south facing balcony polaris is not visible. So I used my smartphone for justification (level for alt; compass for azumith), which was sufficient. Nevertheless, my brain was not totally awake that morning and I thought: “Hmm, it’s almost winter solstice, so I need to substract 20°…”. Wrong! Polaris is always north, no matter of season, so for 50°N I need to level it always to 40°.


See also