Remote imaging, processing pipeline, and observing plans. Merged from itelescope + astro-pipeline.
laurence
3eb5ab6a03
The four-image set worked out on Centaurus A is now generated for any target, because its value is the comparison: the same data at four levels of treatment, so a viewer can see what processing did and did not add. colour.py's assembly is driven by flags - gradient, neutralise, denoise, saturation, hdr, protect-compact - so the baseline and the fully corrected version come from ONE code path and the only differences between them are the ones named. Image 3 applies what the measurements justify rather than a house style. Each item is there because measuring the first session caught the conventional version getting something wrong: a plane fit that had absorbed 17.9 ADU/px of galaxy halo, a core flattened by a white point set by field stars, deconvolution ringing around every bright star, and denoising erasing faint compact sources that turned out to be globular clusters. Compact sources are now explicitly protected from smoothing - 2374 of them on NGC 2030. The close-up revealed a real design error, caught by its own assertion. Forcing a square crop cannot contain a target wider than the frame is tall, which is the normal case for a nebula in a wide field, and the assertion fired rather than silently cutting the subject in half. Crops are no longer square, and when a target genuinely fills the field the close-up is skipped with that said plainly - re-saving image 3 under a name claiming to be a close-up would be worse than producing nothing. science.py adds the measurements that generalise to any target: photometric calibration from the field's own Gaia stars, the limiting magnitude actually reached, a source catalogue with calibrated magnitudes, an annotated field placed by the plate solution, and a radial surface-brightness profile. Object-specific analyses stay hand-driven, because a cluster survey suits a galaxy and is meaningless for a nebula. All of it depends on astrometry, so an unsolved session gets no science and says so instead of quietly producing less. NGC 2030 calibrates to a zero point of 24.794 with 0.202 mag scatter on 917 stars, 3470 sources, limiting G of 18.2. |
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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.