What is in it
One complete session from a Celestron Origin, as the telescope saved it: 41 light frames of 25 seconds (17 minutes of light in all), taken on 9 July 2026 from a suburban backyard, with the flat, dark and bias frames the Origin took for that night. The Origin’s own finished stack is not included, so the picture you get is OriginStack’s.
- The target
The Whirlpool Galaxy (M51) and its companion NGC 5195, in a wide field: at the Origin’s 335 mm focal length the pair is small in the middle of a field of stars. That is what an Origin frame really looks like, which makes it a fair test.
- Location removed
The files carry no GPS position, altitude or airmass, and the camera’s serial number is replaced. The pixels are untouched, and the stack comes out bit for bit the same as it does with the original files. The capture date and time stay.
- Not a full night
41 frames is a short session, so the result is noisier than a stack of a few hundred. It is enough to show every step working; the gallery and the before and afters show what a longer night gives.
Step by step
- 1. Install OriginStack
Get the installer for your system from the Install section on the home page (Windows, Mac or Linux; no Python needed) and open the app.
- 2. Download and unzip the sample
Download OriginStack-sample-whirlpool.zip (450 MB) and unzip it. You get a folder called
sample_whirlpoolholding the frames. Leave the files as they are: do not rename or move any of them.- 3. Choose the folder
In OriginStack, pick the
sample_whirlpoolfolder as the light-frames folder. The app counts the frames (41 lights) and reads the target, Whirlpool Galaxy, from the session’sinfo.json. Leave What did you image? on Auto-detect and How should it run? on Full quality.- 4. Press Start
The phase bar moves through the stages: processing and scoring each frame, aligning them, stacking, then the finishing steps. The log shows the same lines the command line prints, and the preview on the right updates at each milestone. On an 8-core laptop the whole run took 69 seconds; a slower machine takes a few minutes.
- 5. Look at the result
When it says Done, the stacked picture is in the preview, and the files are next to the folder you chose: the linear stack (
.fits), a preview picture (.jpg) and the settings it used (_config.toml). Compare your picture with the one below.
Prefer a terminal? From a source install, the same run is python originstack.py -d sample_whirlpool -o whirlpool.fits.
The result to expect
All 41 frames are kept (100%) and stacked into a 2025×3025 picture with 17.1 minutes of light. Yours may differ a little from this one, since the settings are chosen from the data and improve between versions, but it should show the same things.
- If yours looks very different
A near-black picture, a strong colour cast or fewer than 41 frames stacked usually means the files were changed on the way: a zip tool that rewrote them, or frames moved out of the folder. Unzip again and try once more. If it still looks wrong, ask in Discussions, or use Report a problem in the app, which fills in the version, system and log for you.
Where next
- Change the look
With the run finished, the Stretch and Colour bar above the preview offers every stretch; the stretch gallery shows what each does. Apply to JPEG saves the one you like.
- Switch finishing steps off and on
The Post-processing steps panel under the preview has a box for each step the run used. Clear one, and only that step and the ones after it are redone, so you can see what each step contributes without running everything again.
- Look at single frames
Click a row in the recent-frames table to see that frame on its own while the run goes on, and compare it with the stack to see what 41 frames add.
- Then your own data
Copy a session folder off your Origin (or see other cameras), choose it the same way and press Start. The Origin guide covers what is in a session folder and how to read the result; the app page goes through every screen.