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Troubleshooting by stage

Every message below was produced by valerian 0.2.0 on the real captures used in the tutorials; the tutorial for each stage has the full context. Messages are printed on standard error, the command exits 1 and writes nothing for that step.

Install and start-up

SymptomCause and fix
FAILED from sha256sum -c, or a different hashThe download is damaged or is not the published file. Download it again. Tutorial 1
valerian: command not foundThe program is not on PATH. Run it by its path or add its folder.
catalogue: not found in valerian info; no star catalogue found; looked for gaia-dr3-g11.vcat in: ...The catalogue is not beside the program. Copy it there or set VALERIAN_CATALOGUE. Catalogue file
gpu: unavailable (could not open GPU device: ...)No Vulkan (Windows: DirectX 12) driver. Commands still run on the processor. Tutorial 11
An error naming GLIBC_2.35The Linux build needs glibc 2.35 or newer.

Calibrate

SymptomCause and fix
nothing to calibrate with: give at least one of --bias, --dark and --flatNo calibration frames given. --auto-cosmetic alone is enough: it repairs isolated hot and cold pixels in each light (issue 60, fixed).
a master frame differs in size from the lightA calibration frame has another size or binning than the lights.
<path> does not exist, <folder> contains no FITS filesA wrong path, or a folder with no .fits, .fit or .fts.
dark scaling needs a master dark made with a master bias--scale-dark exposure or optimise needs --bias.

Tutorial 2

Register and stack

SymptomCause and fix
registered 10 of 25 frames, skipped: registration failed: best hypothesis matches only 3 stars (need 6)The frames do not share a field (several panels). Register one panel at a time.
frame 25 has 3 planes, the first has 1Mono and colour frames mixed.
fewer than two frames registered; nothing to stackOne frame, or none matched the others.
skipped, only 77 stars / skipped, FWHM 3.59 px is too soft--min-stars or --max-fwhm-ratio left the frame out; the table says which.
reference frame 99 out of range (60 frames)--reference counts from 0.
--low and --high change nothingFixed (issue 62): with --rejection auto they change the limits of the scheme auto picks. They have no effect (and a note says so) with none, minmax or two frames or fewer.

Tutorial 3, tutorial 4

Background extraction

SymptomCause and fix
background fit declined, plane left as it is: 62% of the image is star, nebula or targetToo little clear sky. Not an error; the plane is written unchanged.
is a raw colour mosaic; calibrate it with --debayer firstStack first: background works on stacks, not raw frames.
polynomial degree must be 0 to 6Use a spline for a more complex surface.
The nebula got dimmerThe model follows the target: lower --degree.

Tutorial 5

Stretch and star removal

SymptomCause and fix
--black and --white need a curve with its own parametersAdd --curve mtf --midtone M, or arcsinh or ghs.
the image records no stretch (no STRETCH keyword)--invert on a file not made by valerian stretch.
A stretched file stretched again gives a grey, flat pictureThe command does not detect it. Start from the linear file.
22 per cent of the picture filled by starless--threshold too low: noise taken for stars.

Tutorial 6, tutorial 7

Plate solve and colour

SymptomCause and fix
no match in 9 patches of sky: the field is not where the hint says, the scale is outside ...Wrong position or scale, or too few catalogue stars: use --blind with --scale-range, or a deeper catalogue.
only 2 stars were detected; at least 10 are neededThe image has too few stars (a dark frame, a clouded frame).
this image has been stretched; colour calibration works on the linear imageRun photocal before stretch.
has no world coordinate system and the header lacks a position and scale to solve oneRun valerian solve first, or give --wcs.
only 36 usable stars of 36 measured; at least 40 are needed--min-stars is above what the field offers.

Tutorial 8, tutorial 9

Drizzle

SymptomCause and fix
9.263 % of the output without dataToo few or too little-dithered frames for the scale: use a larger --pixfrac or a smaller --scale, or more frames.
pixfrac must be above 0 and at most 1--pixfrac out of range.
the drizzle scale must be 0.25 to 8--scale out of range.

Tutorial 10

GPU

SymptomCause and fix
--backend gpu: no suitable GPU adapter foundNo adapter at all. Use --backend cpu.
gpu: llvmpipe (...) (Vulkan, Cpu) and a slow stackOnly the software adapter exists. --backend auto uses the CPU instead (issue 58, fixed); --backend gpu forces the software adapter and says it is slower.
GPU: ... N fell back to the CPU (130 frames is more than the 128 the kernel holds)Reported fall-back, not an error.
--frames must be 3 to 128valerian bench limit.

Tutorial 11

Any command

SymptomCause and fix
failed printing to stdout: Broken pipeFixed (issue 59): a command piped to head now ends quietly. Update Valerian if you still see it.
Out of disk spaceRegistered and calibrated copies are 32-bit float: 1.4 GB for sixty Seestar frames, 65 MB per ASI1600 frame.