Astrophotography · Windows

Your stack,
as a video.

SNRflow turns a night of imaging into a clip where your target climbs out of the noise, frame after frame — with the signal-to-noise ratio measured on your own data.

Download for Windows See how it works

Free for personal use Works with Siril + ffmpeg Tells you how many hours you still need

Made to be posted

It comes out ready for your feed.

Vertical, the right length, nothing to re-edit. Drop it straight into Instagram, TikTok or YouTube Shorts — and tag it #SNRflow so the rest of us can find your night.

23:41

kaanatu

Paris · 4 nights

K A A N A T U

NGC 6888

HA / OIII · BORTLE 9 · PARIS

Integration

0h 00m

Frames

SNR

FWHM

Captured

MAY 2026

Timeline / 4 nights

NGC 6888, the Crescent Nebula, in HA and OIII

signal

sky

K A A N A T US N R F L O W

248 31

kaanatu 6h45 on the Crescent from a Bortle 9 balcony. 81 × 300 s, ASI585MC Pro. #SNRflow #astrophotography #NGC6888

Every figure is measured. Every block is optional.

That post is one real session: 6 h 45 min of Crescent Nebula, 81 subs of 300 s on an ASI585MC Pro. The orange curve is the SNR the stack actually reached; the dashed one is the √n law it is chasing. The two faint boxes on the image are where those numbers come from.

Tap a pill to drop a block — this is the app's real template system.

Brand Title Integration SNR graph Frames SNR FWHM Captured Timeline Watermark

typing — exposure, target and filter are read from the FITS headers

to place both measurement zones automatically

blocks you can switch on or off

you have shot 6h 45m · SNR 36.8

curve fitted SNR = 4.09 √n

to reach SNR 45, aim for

10h 06m

next hour → +7.2 % SNR

stop paying off past 9h 45m

The real question

And how many hours should the target get?

You shot six hours. Was that enough? SNRflow fits the square-root law to your measured curve and inverts it: the time to reach a given SNR grows as the square of it, so it can tell you what the next hour is actually worth — and the total past which it is worth less than you care about.

Extrapolated from your own curve, not from a chart
Gives the hours to any SNR you set as a goal
Warns you when your curve stops obeying the law

See the formula

How it works

You point. It reads, measures, stacks, exports.

Four steps — and you only really do the first one.

Drop in your lights

SNRflow opens the FITS headers and pulls out the exposure time, the target name and the filter. You type nothing.

Let it find the zones

One click puts the signal box on the brightest part of the object and the background box on the emptiest patch of sky.

Watch the stack grow

Siril calibrates and registers. Then every added light updates the running stack — and you see the noise physically drop away.

Post it

Out comes a vertical clip, the length you asked for, ready for Instagram or TikTok.

The longer version

Your stack,as a video.