Telescope Collimation Lab

Keep star-test photos, manual centering points and before/after records together on your Android phone or tablet. MEASURE WITH THE PHOTO Import a still PNG or JPEG. Mark the reference ring center, inner-feature center and ring edge. Tap the image, pinch to zoom, enter precise X/Y values, nudge one working pixel and undo placements. Original bytes stay unchanged with a SHA-256 checksum. EXIF orientation is applied to the sRGB working preview, with a maximum 2048-pixel edge. COMPARE RECORDED ROUNDS Select two rounds and view their marked photos and centering percentages. Keep titles, notes, seeing and magnification. Numeric rounds are available for offsets and radius already measured in matching units. New sessions contain no invented measurement. An optional synthetic ring study is clearly labeled; it is not an astronomical observation or optical simulation. EXPORT A SOURCE-BACKED RECORD Create annotated PNG images, a centering PDF with every round, a full CSV, a restorable JSON backup and a ZIP containing original photo sources and a SHA-256 manifest. Original metadata remains in source files. Saved exports are independent of later session edits or deletion. Preview PDF pages, save files with Android's system controls or choose a sharing destination. Import a JSON backup as a separate restored session. ORGANIZE YOUR WORK Save telescope sessions, edit notes, duplicate a session and explicitly confirm deletion. A wide tablet workspace places the photograph beside its measurements. The iOS photo-backup-1 JSON format is accepted when source and working image dimensions match; malformed or incompatible files are rejected without replacing existing sessions. MEASUREMENT SCOPE The result is manual image-plane geometry: center distance divided by marked reference radius, multiplied by 100. Image direction is 0 degrees right and 90 degrees down; zero offset has no defined direction. A smaller marked offset alone does not establish optical collimation. Focus, seeing, reference-ring selection, scale and orientation affect comparisons. Follow your telescope maker's procedure and re-center the star between observations. No automatic ring detection, optical pass/fail test, sky bearing, calibrated screw-turn instruction or camera capture. LIMITS Single still PNG/JPEG, up to 8 MB and 30 megapixels, at least 32 pixels per side. Up to 100 sessions, 500 rounds per session, 128 MB of retained photos, 20 saved exports and a 1 GB total library. JSON backup import: 180 MB. PDF excerpts may be shortened with a continuation label; CSV and JSON retain full notes. No FITS, RAW, animation or video. Paid once. No account, subscription, in-app purchases, ads, analytics or network permission. Android automatic app backup is disabled; save important backups yourself. Uninstalling removes local app data. Screenshots show the explicitly selected synthetic ring study.

Initial Android release: manual photo centering, three-point precision controls, before/after comparison, annotated images, PDF/CSV and source-bearing JSON/ZIP exports.