{ "schemaVersion": "1.0.0", "title": "SN 2026aaiv in NGC 7331 — Processing Companion", "session": { "startedLocal": "2026-09-09T22:48:02-04:00", "finishedLocal": "2026-09-10T00:42:22-04:00", "application": "Siril 1.4.4", "log": "2026-09-10T04.42.42.log", "sourceRoot": "/Volumes/AstroScratch/SN/SN2026aavi", "interpretation": "A clean-room reconstruction from the completed Siril log, the Naztronomy preset, saved FITS products, conversion manifests, and timestamped snapshots. Earlier editing runs were not used." }, "target": { "name": "SN 2026aaiv", "workingArtifactLabel": "SN2026aavi", "host": "NGC 7331", "classification": "Type Ia", "coordinatesJ2000": { "raDecimalDegrees": 339.27341, "decDecimalDegrees": 34.409825, "raSexagesimal": "22:37:05.618", "decSexagesimal": "+34:24:35.37" }, "tnsUrl": "https://www.wis-tns.org/object/2026aaiv" }, "metrics": { "candidateFrames": 1405, "stackedFrames": 1002, "totalExposureSeconds": 23200, "totalExposureDisplay": "6h 26m 40s", "comparisonDimensions": "3171 × 1784", "detailDimensions": "2541 × 2541", "sessionDurationDisplay": "1h 54m" }, "acquisition": [ { "id": "historical-session", "label": "Historical session", "role": "pre-discovery source", "dates": ["2026-07-20", "2026-08-10"], "candidateFrames": 750, "stackedFrames": 464, "exposureSeconds": 7060, "exposureDisplay": "1h 57m 40s", "exposureMix": "503 × 10s + 241 × 30s + 6 × 60s", "retentionPercent": 61.9, "artifact": "NGC_7331_464x10sec_7060s_drizzle-2-0x_2026-09-09_2257_session1_IRCUT.fit", "evidence": "observed" }, { "id": "recent-session", "label": "Recent session", "role": "post-discovery source", "dates": ["2026-09-05", "2026-09-06", "2026-09-07"], "candidateFrames": 655, "stackedFrames": 538, "exposureSeconds": 16140, "exposureDisplay": "4h 29m", "exposureMix": "655 × 30s", "retentionPercent": 82.1, "artifact": "NGC_7331_538x30sec_16140s_drizzle-2-0x_2026-09-09_2303_session2_IRCUT.fit", "evidence": "observed" } ], "stackingRecipe": { "processor": "Naztronomy OSC preprocessing", "backgroundExtraction": true, "astrometricRegistration": true, "drizzle": "2×", "pixelFraction": 0.5, "featherPixels": 20, "rejectionFilters": "3σ roundness, weighted FWHM, star count, and background", "normalization": "additive scaling with output normalization and RGB equalization", "weighting": "Weighted FWHM", "calibrationNote": "The saved preset attaches no darks, flats, or biases. This describes the preset, not the complete history of the source data." }, "graph": { "nodes": [ {"id":"historical","label":"Historical lights","detail":"750 candidates · Jul/Aug","lane":"source","state":"retained"}, {"id":"recent","label":"Recent lights","detail":"655 candidates · Sep 5–7","lane":"source","state":"retained"}, {"id":"stack-historical","label":"Historical stack","detail":"464 frames · 7,060s","lane":"stack","state":"retained"}, {"id":"stack-recent","label":"Recent stack","detail":"538 frames · 16,140s","lane":"stack","state":"retained"}, {"id":"combined","label":"Combined master","detail":"1,002 frames · 23,200s","lane":"stack","state":"retained"}, {"id":"register","label":"Matched comparison pair","detail":"plate solve → register → crop","lane":"common","state":"retained"}, {"id":"linear-cleanup","label":"Shared linear cleanup","detail":"SPCC → BlurX → NoiseX","lane":"common","state":"retained"}, {"id":"separate","label":"Star separation","detail":"StarXTerminator on both pair members","lane":"common","state":"retained"}, {"id":"galaxy","label":"Galaxy background","detail":"combined starless master · alternate stretch","lane":"background","state":"retained"}, {"id":"recent-stars","label":"Recent star layer","detail":"from the 538-frame recent stack","lane":"stars","state":"retained"}, {"id":"reference-stars","label":"Reference star layer","detail":"from the 1,002-frame combined master","lane":"stars","state":"retained"}, {"id":"after","label":"After presentation","detail":"shared galaxy + recent stars","lane":"output","state":"final"}, {"id":"before","label":"Before presentation","detail":"shared galaxy + combined-master stars","lane":"output","state":"final"}, {"id":"difference","label":"Transient isolation","detail":"PixelMath difference gate · k = 90","lane":"experiment","state":"retained"}, {"id":"isolated","label":"Isolated-SN presentation","detail":"shared galaxy + thresholded difference","lane":"output","state":"final"}, {"id":"normalize","label":"Comparison normalization","detail":"sequence-level black-point shift","lane":"output","state":"retained"}, {"id":"detail","label":"C30 detail","detail":"crop → solve → 3× Lanczos4 → re-solve","lane":"detail","state":"final"} ], "edges": [ ["historical","stack-historical"], ["recent","stack-recent"], ["stack-historical","combined"], ["stack-recent","combined"], ["stack-recent","register"], ["combined","register"], ["register","linear-cleanup"], ["linear-cleanup","separate"], ["separate","galaxy"], ["separate","recent-stars"], ["separate","reference-stars"], ["galaxy","after"], ["recent-stars","after"], ["galaxy","before"], ["reference-stars","before"], ["recent-stars","difference"], ["reference-stars","difference"], ["galaxy","isolated"], ["difference","isolated"], ["after","normalize"], ["before","normalize"], ["isolated","normalize"], ["after","detail"] ] }, "timeline": [ {"id":"setup","time":"22:48","phase":"Stack","title":"Load the clean-run preset","summary":"The Naztronomy preset defined two source sessions and a 2× drizzle, weighted-FWHM stacking recipe.","evidence":"observed"}, {"id":"historical-stack","time":"22:57","phase":"Stack","title":"Complete the historical stack","summary":"464 of 750 candidate frames were retained, totaling 7,060 seconds.","image":"assets/checkpoints/stack-reference.jpg","evidence":"observed"}, {"id":"recent-stack","time":"23:03","phase":"Stack","title":"Complete the recent stack","summary":"538 of 655 candidate frames were retained, totaling 16,140 seconds.","image":"assets/checkpoints/stack-recent.jpg","evidence":"observed"}, {"id":"combined-stack","time":"23:04","phase":"Stack","title":"Build the 1,002-frame master","summary":"The two session stacks were registered and stacked into a 23,200-second combined master.","evidence":"observed"}, {"id":"pair","time":"23:06","phase":"Align","title":"Create a matched comparison pair","summary":"The recent stack became pair 00001; the combined master became pair 00002. Both were plate-solved, registered, and cropped to 3171 × 1784.","evidence":"observed"}, {"id":"spcc","time":"23:11","phase":"Calibrate","title":"Calibrate both images independently","summary":"Gaia DR3 spectrophotometric color calibration succeeded on each aligned image, followed by a final astrometric synchronization.","evidence":"observed"}, {"id":"linear","time":"23:13","phase":"Clean","title":"Apply common linear cleanup","summary":"BlurXTerminator and NoiseXTerminator produced matched clean linear images before separation.","image":"assets/checkpoints/linear-cleanup.jpg","evidence":"observed"}, {"id":"starx","time":"23:15","phase":"Separate","title":"Split each image into stars and background","summary":"StarXTerminator produced two starless layers and two star layers. This is the branch point that makes the later comparison possible.","image":"assets/checkpoints/starless.jpg","evidence":"observed"}, {"id":"stretch-fork","time":"23:40","phase":"Develop","title":"Begin the retained alternate stretch","summary":"The combined starless layer was reopened as a fresh branch and developed with SCUNet PSNR 0.50, Statistical Stretch, VeraLux Curves, then SCUNet GAN 0.80.","image":"assets/checkpoints/stretch.jpg","evidence":"observed"}, {"id":"galaxy-background","time":"23:59","phase":"Develop","title":"Commit the shared galaxy background","summary":"The retained branch was saved as Galaxy Background.fit. One developed galaxy image now anchors every presentation state.","image":"assets/checkpoints/galaxy-background.jpg","evidence":"observed"}, {"id":"recompose","time":"00:00","phase":"Compose","title":"Test star-layer recompositions","summary":"The shared galaxy background was paired in turn with the recent and combined-master star layers, with color-profile conversion handled during recomposition.","image":"assets/checkpoints/recomposition.jpg","evidence":"observed"}, {"id":"after-output","time":"00:07","phase":"Compose","title":"Save the After presentation","summary":"Galaxy Background + recent-session stars. The result was plate-solved at 1.188 arcsec/px.","evidence":"observed"}, {"id":"before-output","time":"00:10","phase":"Compose","title":"Save the comparison baseline","summary":"Galaxy Background + combined-master stars. The file is labeled Before, but its star layer is a blend of both source eras.","evidence":"observed"}, {"id":"isolate","time":"00:16","phase":"Experiment","title":"Suppress the common foreground star field","summary":"PixelMath compared the recent and combined-master star layers. A 90× reference gate rejected the small residual differences and retained the transient signal.","evidence":"interpreted"}, {"id":"isolate-save","time":"00:20","phase":"Experiment","title":"Save the isolated transient layer","summary":"The sparse result was saved as isolated_supernova.fit, then recomposed with the shared galaxy background.","evidence":"observed"}, {"id":"normalize","time":"00:30","phase":"Finish","title":"Normalize the three comparison states","summary":"After, baseline, and isolated-SN presentations were linked as a sequence and received the same generalized-hyperbolic black-point shift.","evidence":"observed"}, {"id":"detail","time":"00:32","phase":"Detail","title":"Create the C30 detail view","summary":"The After presentation was cropped to 847 × 847, solved, resampled 3× with Lanczos4 to 2541 × 2541, and solved again at 0.396 arcsec/px.","image":"assets/checkpoints/galaxy-detail.jpg","evidence":"observed"}, {"id":"annotate","time":"00:41","phase":"Verify","title":"Verify the transient coordinates","summary":"A coordinate annotation landed at 22:37:05.6 +34:24:35.4 within NGC 7331.","image":"assets/checkpoints/astrometric-annotation.jpg","evidence":"observed"}, {"id":"export","time":"00:42","phase":"Export","title":"Export the four presentation images","summary":"Before, After, isolated-SN, and C30-detail FITS products were batch-exported to PNG.","evidence":"observed"} ], "methods": [ {"label":"Transient isolation","value":"iif(recentStars - k * referenceStars > 0, recentStars - k * referenceStars, 0)","parameters":"k = 90","source":"Siril PixelMath"}, {"label":"Coordinate annotation","value":"show -clear \"SN 2026aaiv\" 339.27341 +34.409825","parameters":"J2000","source":"Siril console"}, {"label":"3× detail solve","value":"focal length 250.10 mm · pixel size 0.48 µm","parameters":"0.396 arcsec/px · 16′45.9″ square field","source":"Siril plate solution"} ], "outputs": [ {"id":"before","label":"Comparison baseline","shortLabel":"Before","image":"assets/final/before.jpg","dimensions":"3171 × 1784","note":"Shared combined-starless galaxy background with the combined-master star layer."}, {"id":"after","label":"Recent-session presentation","shortLabel":"After","image":"assets/final/after.jpg","dimensions":"3171 × 1784","note":"Shared combined-starless galaxy background with the recent-session star layer."}, {"id":"isolated","label":"Foreground-star-suppressed presentation","shortLabel":"Isolated SN","image":"assets/final/isolated.jpg","dimensions":"3171 × 1784","note":"Illustrative composite using a thresholded star-layer difference; not a photometric difference image."}, {"id":"detail","label":"C30 and surrounding galaxies","shortLabel":"Detail","image":"assets/final/detail.jpg","dimensions":"2541 × 2541","note":"A 3× resampled detail crop from the After presentation."} ], "integrityNotes": [ "The working directory and several saved filenames transpose the final letters as SN2026aavi. The official TNS designation used by this companion is SN 2026aaiv.", "The isolated-SN presentation is a visualization experiment, not an independent measurement of transient flux.", "The presentation labeled Before uses the star layer from the 1,002-frame combined master, which contains both acquisition eras. It is a comparison baseline rather than a strictly pre-event observation.", "All three comparison outputs share the same developed starless galaxy background, intentionally holding galaxy treatment constant while the star-layer evidence changes.", "The 3× detail resample changes sampling, not optical resolution; the corrected plate solve uses 0.48 µm effective pixels with the original approximately 250 mm focal length." ] }