Remote imaging, processing pipeline, and observing plans. Merged from itelescope + astro-pipeline.
laurence
0aa37cc503
measure.py produces the numbers used to choose a registration reference and to weight the stack - sky, noise, seeing - and caches each frame's star list, because registration and the plate solve both need it and detection costs far more than reading a small array back. Frames are opened one at a time; a 4096x4096 float32 frame is 67 MB and a session holds ninety of them. register.py aligns everything onto a single reference and combines per filter. One reference for ALL filters, not one per filter, which is what makes the masters pixel-aligned so the colour composite needs no further registration. The reference is the sharpest frame of the filter with the most signal, because the reference sets the output grid and a poor choice costs resolution everywhere, permanently. The case worth the care is NGC 6744: luminance at bin1 4096x4096 and colour at bin2 2048x2048, so frames share neither shape nor pixel scale. Asterism matching already returns a similarity transform including scale, so the maths was never the problem; the trap is assuming the warp output is the same shape as its input, which would write a bin2 frame onto a bin2 grid that silently fails to line up with a bin1 reference. Every warp is now given the reference shape explicitly. Verified rather than assumed: after stacking, the upsampled bin2 colour masters align to the bin1 luminance master to within 0.04 pixels, across about 245 matched stars per channel. Sigma clipping is skipped below three frames, where there is nothing to reject against and clipping would only discard signal - which matters because one session has a single frame per filter. Tested on three sessions covering the awkward shapes: RGB without luminance, SHO with one frame per filter, and the mixed bin1/bin2 LRGB. |
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|---|---|---|
| docs | ||
| itelescope | ||
| observing/eclipse-2026-menorca | ||
| pipeline | ||
| state | ||
| .gitignore | ||
| CLAUDE.md | ||
| README.md | ||
astrophotography
Everything to do with taking, processing and understanding astronomical images: the remote telescopes, the code that turns their frames into pictures and measurements, and the plans for observing in person.
Formed by merging the itelescope and astro-pipeline repositories, with the
history of both preserved.
Layout
| Directory | What it is |
|---|---|
| itelescope/ | The iTelescope.net remote telescope network: a review of every scope, a southern-target guide, the observing plans, and the points drain campaign |
| pipeline/ | The processing and analysis code. Calibration, stacking, plate solving, rendering and the science analyses |
| observing/ | Plans for observing in person. Currently the total solar eclipse of 12 August 2026 from Menorca |
| state/ | Project state under the Default Workflow: objective, current work, decisions, working notes |
| docs/ | The Default Workflow itself: branching, commits, documentation policy, cost control |
Start here
- Planning or reviewing a remote imaging run: itelescope/CAMPAIGN.md and itelescope/TELESCOPES.md
- Processing a session's data: pipeline/README.md
- What is happening right now: state/TODO.md
- Why something was done a particular way: state/DECISIONS.md
Where the image data lives
Not in this repository. A single calibrated frame is 61 MB and a session
runs to several gigabytes, so sessions stay on disk and the code finds them
through the ASTRO_SESSION environment variable:
set ASTRO_SESSION=...\NGC5128\20260721
python pipeline/stack.py
Each session directory carries its own METHODS.md describing what was done to
that data and what was found, written for a reader who was not there. The code
lives here; the pixels and the account of them live with the data.
Things learned the hard way
Recorded because each cost real time or real money, and because each is a requirement for anything built next rather than a curiosity:
- Measure whether a core is saturated before buying time to fix it. A foreground star 69 arcsec from Centaurus A's nucleus was mistaken for the galaxy, and a telescope booking was made to solve a problem that did not exist. Filter the stars out of the measurement first.
- Vet moving-object candidates in detector coordinates. Registration holds the sky still, so it drags sensor defects across the frame on perfectly straight, constant-rate tracks. Hot pixels are better-behaved asteroids than real asteroids. One cut took 141 confident spurious detections to zero.
- Never compare an aperture magnitude against a point-source catalogue without checking the source is a point. A resolved object looks exactly like a 2.8 magnitude outburst.
- Never fit a sky background to a field the target fills. A plane fitted around a large galaxy eats its halo, measured at -17.9 ADU/px. Fit the background and a source model together.
- A photographic ND filter is not a solar filter. It passes the infrared that carries the heat.