Other cameras

Seestar S50 and S50 Pro

The Seestar keeps its individual frames only if Save Each Frame is on in the Seestar app's settings. They are saved in a folder named after the target with _sub at the end, for example M 31_sub, inside MyWorks. Copy that folder over USB or Wi-Fi and choose it in OriginStack.

No calibration frames needed

The Seestar subtracts its dark from every frame before saving it and takes no flats, so the folder holds lights only. Leave --flat-from-lights off: a flat made from the lights takes in the galaxy or nebula too, unless the target moves well across the frame.

Sky position and colour

The frames record where the telescope pointed, the focal length and the pixel size. The first frame is plate-solved from them against Gaia, which sets the colours from Gaia stars, as on an Origin session.

Field rotation

In alt-az mode the field turns during the night (21° over 45 minutes on one M101 session). Registration measures and removes it; the edges at least half of the frames cover are kept, a little noisier than the middle.

Tested on

M101 on an S50 (214 frames of 10 s, alt-az) and M31 on an S50 Pro (133 frames of 10 s, equatorial mode). The Seestar app's own stacked file is not a raw frame; choose the _sub folder, not the target folder above it.

File formats

Every format below loads through the same path, so they can be mixed in one folder. The installers include everything needed; from source, RAW and TIFF need pip install rawpy tifffile.

Setting up the folder

Put the light frames and any calibration frames in one folder and choose that folder, or keep a calibration library elsewhere and point --cal-dir at it: the best-matching frames of each type are picked from it by ISO, sensor temperature, exposure, filter and frame size. Subfolders of a single night are not searched; a folder whose subfolders each hold a night is stacked as several sessions.

How frames are sorted

A file whose name contains dark, flat or bias is that kind of calibration frame; otherwise the IMAGETYP header decides, in any of the usual spellings (DARK, Dark Frame, Flat Field, Bias Frame, Offset...), and a zero-length exposure is a bias. Everything else is a light.

Darks

Darks are matched to the lights by sensor temperature and exposure time, and scaled when the exposure differs. A library of darks at several temperatures can be modelled instead (--dark-temp-model).

Flats

Flats are normalised and divided out. With no flats, --flat-from-lights estimates one from the lights themselves; it is approximate.

Leave out

Dark flats are recognised (by name or IMAGETYP) and left out, with a note in the log: there is no separate dark-flat step, and the flats are bias-corrected instead, so keep bias frames in the folder. Earlier OriginStack outputs in the folder are recognised and skipped.

Colour sensors and the Bayer pattern

A one-shot-colour sensor records a Bayer mosaic, and the debayering step needs to know which corner of each 2×2 block is red.

Where the pattern comes from

The BAYERPAT (or COLORTYP) header for FITS, the file itself for RAW, the colour ID for SER. With none of these it assumes RGGB.

A wrong pattern is caught

Some software writes a pattern that is flipped top to bottom against the pixel data; the Origin does. Each session's declared pattern is checked against the mosaic itself, and the flipped version is used when the two green sites disagree by more than a real sensor could.

Override it.json sidecar

A single-channel TIFF, or any frame with a missing or wrong header, takes its pattern from a JSON file with the same name next to it, for example light_001.json containing {"bayerPattern": "GRBG"}.

What it reads from the headers

What needs an Origin

The session fileinfo.json

The Origin writes the target, the site location and a first sky solution into each session folder. Other cameras get these from the headers above instead, so a capture program that writes a good header gives the same results.

The camera profile

The Origin's camera gain is measured and built in. For other cameras, photometry measures the gain from pairs of bias and flat frames when the folder has them, and otherwise falls back to the header's GAIN/EGAIN.

Tuned defaults

The automatic settings were tuned on Origin data: 10 to 30 second subs at about 1.5 arcseconds per pixel. They adapt to the frames, but very different data, such as long DSLR exposures at a wide field, may be better served by choosing the target type yourself.

Limits today