{
  "schemaVersion": "1.0.0",
  "title": "AT 2026aabo in M31 — Processing Companion",
  "session": {
    "startedLocal": "2026-09-11T00:32:04-04:00",
    "finishedLocal": "2026-09-11T09:39:38-04:00",
    "application": "Siril 1.4.4",
    "log": "2026-09-11T13.40.19.log",
    "sourceRoot": "Local AT2026aabo working set",
    "interpretation": "A first-pass reconstruction from the completed Siril log, saved Naztronomy presets, FITS products, sequence artifacts, and timestamped snapshots. Repeated image reads and UI-only experimentation were collapsed unless they changed a saved branch."
  },
  "target": {
    "name": "AT 2026aabo",
    "host": "M31 (Andromeda Galaxy)",
    "coordinatesJ2000": {"raDecimalDegrees": 11.22625, "decDecimalDegrees": 41.5529167, "raSexagesimal": "00:44:54.3", "decSexagesimal": "+41:33:10.5"},
    "tnsUrl": "https://www.wis-tns.org/object/2026aabo"
  },
  "metrics": {
    "candidateFrames": 2031,
    "stackedFrames": 2031,
    "totalExposureSeconds": 90420,
    "totalExposureDisplay": "25h 7m",
    "comparisonDimensions": "1812 × 1359",
    "wideDimensions": "7296 × 5472",
    "sessionDurationDisplay": "9h 8m"
  },
  "acquisition": [
    {"id":"archive-source","label":"Nineteen-session master","role":"wide portrait and shared galaxy source","candidateFrames":2031,"stackedFrames":2031,"exposureSeconds":90420,"exposureDisplay":"25h 7m","exposureMix":"30s, 60s, 120s, and 180s integrations","artifact":"AT_2026aabo_2031x180sec_90420s_drizzle-1-5x_2026-09-11_0428_og.fit","evidence":"observed"},
    {"id":"post-source","label":"Post-transient subset","role":"after star-layer source","candidateFrames":572,"stackedFrames":572,"exposureSeconds":28710,"exposureDisplay":"7h 58m 30s","exposureMix":"495 × 30s + 77 × 180s","artifact":"AT_2026aabo_572x180sec_28710s_2026-09-11_0831_og.fit","evidence":"observed"}
  ],
  "stackingRecipe": {
    "processor":"Naztronomy OSC preprocessing 2.0.3","backgroundExtraction":true,"astrometricRegistration":true,"drizzle":"1.5×","pixelFraction":0.5,"featherPixels":20,"rejectionFilters":"3σ roundness, weighted FWHM, and star count; background rejection disabled","normalization":"additive scaling with output normalization and RGB equalization","weighting":"Weighted FWHM","calibrationNote":"The saved preset records no dark, flat, or bias masters. That describes this run's preset, not necessarily the original calibration history of every source stack."
  },
  "graph": {
    "nodes": [
      {"id":"archive","label":"19 source stacks","detail":"2,031 frames · mixed exposures","lane":"source","state":"retained"},
      {"id":"post","label":"4 post-event stacks","detail":"572 frames · 28,710s","lane":"source","state":"retained"},
      {"id":"archive-stack","label":"1.5× drizzle master","detail":"90,420s · 8954 × 14043","lane":"stack","state":"retained"},
      {"id":"post-stack","label":"Post-event master","detail":"register → stack → crop","lane":"stack","state":"retained"},
      {"id":"master","label":"Wide linear master","detail":"rotate → solve → crop → downsample","lane":"common","state":"retained"},
      {"id":"wide-clean","label":"Wide linear cleanup","detail":"BGE → SPCC → BlurX → NoiseX","lane":"common","state":"retained"},
      {"id":"wide-develop","label":"Wide development","detail":"Statistical Stretch → curves → denoise","lane":"common","state":"retained"},
      {"id":"wide","label":"M31 25h portrait","detail":"7296 × 5472","lane":"output","state":"final"},
      {"id":"match","label":"Three-way matched crop","detail":"post · pre-event · full master","lane":"common","state":"retained"},
      {"id":"separate","label":"Star separation","detail":"StarXTerminator on all three","lane":"common","state":"retained"},
      {"id":"galaxy","label":"Shared galaxy layer","detail":"full-master starless crop","lane":"background","state":"retained"},
      {"id":"post-stars","label":"Post-event stars","detail":"cleaned and color calibrated","lane":"stars","state":"retained"},
      {"id":"pre-stars","label":"Pre-event stars","detail":"dual BlurX → NoiseX → SCNR → SPCC","lane":"stars","state":"retained"},
      {"id":"after","label":"After presentation","detail":"shared galaxy + post stars","lane":"output","state":"final"},
      {"id":"before","label":"Before presentation","detail":"shared galaxy + pre stars","lane":"output","state":"final"},
      {"id":"final-match","label":"Final comparison match","detail":"register → optional BlurX test → MTF match","lane":"experiment","state":"retained"}
    ],
    "edges": [["archive","archive-stack"],["archive-stack","master"],["master","wide-clean"],["wide-clean","wide-develop"],["wide-develop","wide"],["post","post-stack"],["post-stack","match"],["archive-stack","match"],["match","separate"],["separate","galaxy"],["separate","post-stars"],["separate","pre-stars"],["galaxy","after"],["post-stars","after"],["galaxy","before"],["pre-stars","before"],["after","final-match"],["before","final-match"]]
  },
  "timeline": [
    {"id":"stack-run","time":"00:32","phase":"Stack","title":"Begin the nineteen-session Naztronomy run","summary":"The OSC preprocessor handled mixed 30s, 60s, 120s, and 180s session stacks with 1.5× drizzle, per-frame background extraction, astrometric registration, and weighted-FWHM stacking.","evidence":"observed"},
    {"id":"master-save","time":"04:29","phase":"Stack","title":"Commit the 25-hour master","summary":"Nineteen registered session products—2,031 retained frames totaling 90,420 seconds—were combined into an 8,954 × 14,043 drizzle master.","image":"assets/checkpoints/raw-master.jpg","evidence":"observed"},
    {"id":"wide-geometry","time":"07:18","phase":"Frame","title":"Orient, solve, crop, and downsample","summary":"The master was rotated 90°, solved at 1.100 arcsec/px, cropped to 9,728 × 7,296, then reduced to 7,296 × 5,472 with Lanczos4 and solved again at 1.467 arcsec/px.","image":"assets/checkpoints/full-field.jpg","evidence":"observed"},
    {"id":"wide-linear","time":"07:26","phase":"Clean","title":"Build the clean linear portrait","summary":"Automatic background extraction and GraXpert AI background extraction were followed by Gaia DR3 SPCC, BlurXTerminator, and NoiseXTerminator.","evidence":"observed"},
    {"id":"stretch","time":"07:49","phase":"Develop","title":"Retain the second Statistical Stretch","summary":"The retained pass used target median 0.20, linked channels, normalization, HDR compression 0.20 with knee 0.50, and curves boost 0.30.","image":"assets/checkpoints/statistical-stretch.jpg","evidence":"observed"},
    {"id":"wide-finish","time":"08:02","phase":"Develop","title":"Finish the wide-field rendering","summary":"VeraLux Curves, SCUNet Color Real GAN at 0.70, BlurXTerminator, and star recomposition produced the full M31 presentation saved as M31 Andromeda Galaxy 25h.fit.","image":"assets/checkpoints/developed-master.jpg","evidence":"observed"},
    {"id":"wide-verify","time":"08:25","phase":"Verify","title":"Annotate the wide field","summary":"The target coordinate was overlaid at 00:44:54.3 +41:33:10.5 alongside M32, M110, and NGC 206.","image":"assets/checkpoints/wide-annotated.jpg","evidence":"observed"},
    {"id":"post-stack","time":"08:30","phase":"Stack","title":"Re-stack only the post-transient data","summary":"Four source stacks—495 × 30s and 77 × 180s—were registered and combined into a 572-frame, 28,710-second master without drizzle or additional frame rejection.","image":"assets/checkpoints/post-stack.jpg","evidence":"observed"},
    {"id":"post-clean","time":"08:33","phase":"Clean","title":"Prepare the post-event detail crop","summary":"The new master was rotated −22.5°, cropped to 1,812 × 1,359, background-corrected, color calibrated, sharpened, denoised, and neutralized with SCNR.","image":"assets/checkpoints/post-clean.jpg","evidence":"observed"},
    {"id":"match-three","time":"08:49","phase":"Align","title":"Create a three-source comparison frame","summary":"The post-event crop, a 60,720-second pre-event source, and the full 90,420-second master were plate-solved and registered into the same 1,812 × 1,359 geometry.","evidence":"observed"},
    {"id":"separate","time":"08:52","phase":"Separate","title":"Split all three matched images into stars and galaxy","summary":"StarXTerminator created starless and stellar layers for every registered source. The full-master starless crop became the common galaxy base.","evidence":"observed"},
    {"id":"after-compose","time":"08:54","phase":"Compose","title":"Recompose the post-event evidence","summary":"The shared full-master galaxy layer was combined with the post-event star layer. The initially unsaved result was later committed as a FITS product.","evidence":"observed"},
    {"id":"solve-detour","time":"08:56","phase":"Diagnose","title":"Trace a plate-solving failure to stale scale metadata","summary":"Repeated local Gaia and astrometry.net attempts used 361.41 mm with 2.57 µm pixels—1.467 arcsec/px—even though this registered crop retained the 1.100 arcsec/px sampling.","evidence":"interpreted"},
    {"id":"solve-fix","time":"09:11","phase":"Verify","title":"Correct the effective pixel size and solve","summary":"Using 361.41 mm and 1.93 µm solved in about one second at 1.100 arcsec/px, centered at 00:44:54.217 +41:33:17.792. The transient annotation then landed correctly.","image":"assets/checkpoints/detail-annotated.jpg","evidence":"observed"},
    {"id":"pre-clean","time":"09:20","phase":"Clean","title":"Clean the pre-event stellar layer independently","summary":"The pre-event crop received two BlurXTerminator passes, NoiseXTerminator, SCNR, a corrected plate solve, and Gaia DR3 SPCC before its stars were recombined with the shared galaxy layer.","evidence":"observed"},
    {"id":"final-match","time":"09:27","phase":"Finish","title":"Register and visually match the comparison pair","summary":"The reconstructed pre- and post-event views were aligned again. A sequence BlurX test was generated, while the final saved pair came from the registered comparison products with separate MTF channel matches.","evidence":"interpreted"},
    {"id":"save-after","time":"09:35","phase":"Export","title":"Save the After comparison","summary":"The post-event presentation was saved at 1,812 × 1,359 after channel-specific MTF adjustment.","evidence":"observed"},
    {"id":"save-before","time":"09:39","phase":"Export","title":"Save the Before comparison","summary":"The pre-event presentation was saved at the same dimensions after its own channel-specific MTF adjustment.","evidence":"observed"}
  ],
  "methods": [
    {"label":"Target annotation","value":"show -clear \"AT 2026aabo\" 11.22625 +41.5529167","parameters":"J2000 · 00:44:54.3 +41:33:10.5","source":"Siril console"},
    {"label":"Corrected detail solve","value":"platesolve 11.22625 41.5529167 -focal=361.41 -pixelsize=1.93","parameters":"1.100 arcsec/px · 33′13.3″ × 24′55.0″","source":"Siril plate solution"},
    {"label":"Retained Statistical Stretch","value":"target median 0.20 · linked channels · normalize","parameters":"HDR 0.20 · knee 0.50 · curves boost 0.30","source":"Saved UI snapshot"},
    {"label":"Final comparison geometry","value":"Apply Existing Registration","parameters":"1812 × 1359 · rotation approximately +64°","source":"Siril sequence registration"}
  ],
  "outputs": [
    {"id":"before","label":"Pre-event comparison","shortLabel":"Before","image":"assets/final/before.jpg","dimensions":"1812 × 1359","note":"Shared full-master starless galaxy layer plus the independently cleaned 60,720-second pre-event star layer."},
    {"id":"after","label":"Post-event comparison","shortLabel":"After","image":"assets/final/after.jpg","dimensions":"1812 × 1359","note":"The same galaxy layer plus the dedicated 28,710-second post-event star layer."},
    {"id":"wide","label":"M31 25-hour portrait","shortLabel":"Wide field","image":"assets/final/wide.jpg","dimensions":"7296 × 5472 source","note":"The developed portrait branch assembled from all nineteen session stacks."}
  ],
  "integrityNotes": [
    "The source filename says 2031x180sec, but the log and saved per-session stacks show a mixed 30s, 60s, 120s, and 180s exposure set. The authoritative total is 90,420 seconds.",
    "The post-event subset is part of the 90,420-second full master, so that master is used as a shared aesthetic galaxy background—not as independent pre-event evidence.",
    "The Before and After labels refer to the stellar layers. Their common galaxy layer intentionally holds the host-galaxy rendering constant.",
    "The 09:20 plugin invocation is identified from the subsequent undo/redo ledger and saved products; the exact internal BlurX settings are not printed in the Siril log.",
    "The generated bxt_r_comp comparison sequence was inspected, but the final saves read from r_comp products. It is therefore shown as an experiment rather than asserted as retained processing.",
    "This reconstruction omits repetitive image switching, dependency-install chatter, failed load_seq calls, and operations that were explicitly undone without being redone."
  ]
}