[?] How to stack "frozen" (tracked) NeoWise over moving foreground?

Hi all,

first post here: Though a beginner in astrophotography since 6 months, I have also been a professional photographer and experienced visual-only astronomer for over 4 decades. I am also Linux only since 1993 - and sticked with it since … :nerd_face:

Siril and me: So far I only used the provided DSLR scripts and I am very happy with the results, of course providing the common calibration frames (dark, flat, bias) together with my lightframes.

My first and only opportunity to capture “NeoWise” was july 10th, 2020 when I went out to find a flatter horizon here in the Alps:

July 10th, 2020: NeoWise at early dawn, 3 am (CEST)

Two days ago, the late evening of july 27th, 2020 was the first clear sky night since then. We had so many deep gray skies, rain showers, thunderstorms. I had not a single opportunity to view C/2020 F3 (NeoWise) after sunset, so I didn’t know what to expect and how the comet would appear to my eyes.

I left my home valley here in the Alps and went higher up to a big mountain pasture with some not too high mountains and ridges from west > north > east. At 22h (CEST) I saw it first time in my binoculars, very faint, only a poor hint of the tail. Though I decided to take this scenic image series from basic JPEGs (out of RAWs) converted to this ultra short GIF animation:

Comet C/2020 F3 (NeoWise) - late evening animation over a mountain summit

My request, finally: How can I stack the (fixed) comet and the stars with Siril for further processing with StarTools?

I want to get a much more detailed comet (with ion tail - it is there!) and starry sky to be layered on top of a single shot of this lovely mountain scene, so I don’t care for the mountain scene in preprocessing.

Please be merciful with me as - due to my ignorance concerning astronomic image processng (AIP) - I only used one of the provided DSLR scripts all the time. The result.fit served than as the starting point for postprocessing with StarTools.


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Hi, welcome here!
You may take a look at this: Comet registration tutorial
Your animation is great!

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Bravo, I love this picture!

Clear skies,


I quickly wrote an post on our website :wink: https://www.siril.org/2020/07/30/an-animation-of-comet-neowise-created-by-a-sirils-user/

There is a video tutorial in french, the soundtrack has been degraded by google compression, but the images are enough to understand :wink:

@vinvin and @argonothe - thank your for the links to useful material. I will dive into it soon … :slightly_smiling_face:

Hi argonothe,

thanks for posting my animation on the web site. Please do not translate the mountain’s name as the name

Brünstelkreuz (1734m)

… is a landmark, a proper name.

Hint: A good habit to translate landmark names is to keep the proper name and then adding the kind of landmark. In this specific case a good and common understandable translation would be:

Brünstelkreuz mountain or Mount Brünstelkreuz

… instead of the wierd and unrecognizable “Brestle Cross” which neither locals recognize nor strangers find on any map … :sweat_smile:

oops, I’ll fix that right away :wink:

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