Reference
What gets rejected, and why
Every frame is checked before it joins a stack. There are three different outcomes, and they are not the same thing:
- Rejected: the frame never enters a stack. Your raw file stays stored, so if the project's policy changes the frame can be tried again.
- Quarantined: waiting for someone to map its filter name. It continues automatically afterwards.
- Flagged: accepted, usually at a reduced weight. A flag never rejects a frame.
The numbers given are the defaults; each project's owner can change them, and the join page lists what a given project asks. Your dashboard shows the reason against every frame.
Rejected frames
malformed Unreadable or inconsistent file
The header or the data failed a safety check (image size, bit depth, a checksum that differs from what was declared), or the file would not parse.
What to do: Re-save the frame from your capture software; check the file is a complete FITS or XISF image.
duplicate Already uploaded
A frame with exactly the same bytes was uploaded earlier, by you or by someone else.
What to do: Nothing to do. The first copy counts.
no_pointing_hint No idea where it points
The frame has no RA/Dec, no scale, and no confirmed rig, so it could not be matched to the sky.
What to do: Enable RA/Dec and focal-length (or pixel scale) in your capture software's FITS header, or confirm your rig in the plugin so the project can guess.
no_solution Could not be plate-solved
No plate solution was found by any method. The stars it did find are recorded with the frame.
What to do: Check focus and that the frame has stars (narrowband subs of a faint field can be star-poor); make sure the header pointing is roughly right.
pointing_off_target Not on the project's field
After solving, less than 20 % of the frame overlaps the project frame.
What to do: Check you are imaging the right target and that the project frame covers where you point.
fwhm_too_high Stars too soft
The typical star width (FWHM, in arcseconds) is above the project's limit, which is also relative to the project's median once enough frames exist.
What to do: Check focus, seeing and tracking. The project's limit is shown on its join page.
eccentricity_too_high Stars too elongated
The average star shape is more elongated than the project allows (default 0.9).
What to do: Check guiding, tilt and backfocus.
low_star_count Too few stars (clouds?)
The star count is below a fraction of your own session's median, which usually means thin cloud.
What to do: Usually clouds, dew or a failed autofocus. Nothing to fix unless it happens every night.
saturated Background saturated
The sky background is saturated, so the frame carries no usable signal.
What to do: Shorten the exposure or check for stray light; avoid imaging into twilight or a lit sky.
no_usable_stars No measurable star
No unsaturated star with a finite width was found, so the frame's quality cannot be measured.
What to do: Check focus. Every star was saturated, trailed, or unmeasurable.
scale_out_of_bounds Pixel scale too different
The frame's pixel scale is outside the range the owner accepts relative to the project frame (default 0.4 to 2.5 times).
What to do: Ask the owner whether your image scale suits the project, or bin to land inside the accepted range.
calibration_required Calibration frames needed
The project requires calibration and no matching masters exist for this session.
What to do: Upload matching darks and flats (or masters) from the same session and rig.
below_min_exposure Exposure too short
The exposure time is below the project's minimum.
What to do: Use the project's minimum sub-exposure or longer.
osc_not_allowed Colour camera not allowed
The frame comes from a Bayer-pattern camera in a project that accepts mono only.
What to do: Ask the owner to allow one-shot-colour cameras, or contribute a mono camera.
Quarantined frames
unknown_filter Unknown filter name
The filter name did not match anything the normaliser knows. The frame waits until it is mapped, then continues automatically.
What to do: Map your filter name in the plugin; the owner can also map it for the project.
ambiguous_filter Ambiguous filter name
The name could mean more than one filter (for example G with a project that declares Sloan filters).
What to do: Map your filter name explicitly. A single letter like G or I can mean more than one thing.
filter_not_in_project Filter not in this project
The filter was recognised but the project does not list it.
What to do: The owner can add the filter to the project, or you can skip it.
Flags on accepted frames
poor_fit Poor registration fit
The frame fitted the project frame with an error of 0.5 pixel or more. It is accepted at half weight and kept out of gold stacks by default.
high_sky Bright sky
The background is high. The frame is accepted at reduced weight.
trail Possible trail
More than 2 % of the frame's pixels were clipped as outliers in the live stack (a satellite or aircraft). Informational: never rejects by itself.
uncalibrated Not calibrated yet
Accepted without calibration at half weight; it is re-processed automatically when flats arrive.
precalibrated Already calibrated
Your file says it was calibrated (header or history), so the project skipped calibration.
derived Split from a colour frame
A synthetic contribution made by splitting a dual-band colour frame into narrowband channels.
coarse Coarser than the project
Your pixel scale is coarser than the project frame, so the frame is up-sampled and its weight scaled down.
solved_by_master Placed against the stack
The catalogue solve of this frame failed its checks (a short or very narrowband exposure has few stars), so it was registered against the stars of the project's own stack instead. It is accepted; its brightness scale is estimated from the noise.
shared_channel_map Shared colour correction
One colour channel of your colour frame had too few matched stars for its own lateral-colour correction and was placed with the luminance map. Informational.