The retry succeeds: selecting one real exposure member reveals the northern polar field. A blind solve is independently supported by 530 additional catalog matches.
A clean list of 1,613 detections still contains multiple images of the same stars. The common 0, 153, 301 binned-pixel triple pattern yields 46 actual left-anchor positions. Both an all-sky run and a Polaris-assisted run recover the same near-polar field. Other displacement peaks cannot all be combined into one complete exposure sequence; arbitrary chain averages were misleading.
The writing appears to include “UV1693”, “1917 Apr 12”, “Calibration”, “Polaris”, “Seed 30”, and exposure notes. These do not establish telescope focal length, angular field, or the exact meaning of the observing plan.
The compact-source detector ranked at least one detached ink fragment as a strong star candidate. Separately, genuine photographic stars recur at large horizontal displacements, even in quiet strips away from handwriting.
The revised layer uses local contrast in both polarities, expanded inspected writing regions and contextual recovery of short fragments and round digits. Known photographic targets and sampled spectral apertures are protected. It is not OCR and does not reconstruct hidden sky or invent pen strokes.
The selection covers 6.21% of this scan (1,836,303 pixels). Faint marks, scratches and contacts between ink and photographic images remain ambiguous. The cyan overlay shows the wider exclusion footprint used by the photographic remainder; the stroke mask is supplied separately.
The writing PNG is a white, contrast-rendered stencil of bright and dark observed marks. The observed-pixel PNG preserves their stretched scan appearance. Both use original scan coordinates. The photographic remainder displays excluded pixels as black holes. It is neither a clean-sky reconstruction nor a new photometric product. Keep the mask alongside any measurements. Native original-intensity TIFF/FITS products, where generated, remain in the analysis workspace and are not duplicated in this handoff.
This revision recovers short letter fragments, round digits and inspected dark marks, with broader writing regions. The stroke selection grows from 656,207 to 1,836,303 pixels (2.80×). The photographic remainder uses a separate 3-pixel exclusion margin, covering 15.81% of the scan.
The wider selection deliberately favors removing writing. Nearby stars, scratches and ambiguous fragments can also be excluded. Explicit photographic protection regions retain known target images and sampled spectra; this does not establish perfect separation elsewhere.
A blind solve of 46 left-anchor positions finds 12 solver matches with odds 1.08 × 10¹⁷ in index 4112. A separate Polaris-assisted run returns the same field. The center is RA 198.60907774°, Dec +88.71094609°; Polaris lies within the footprint. The recovered native scale is 5.533 arcsec/pixel, essentially the same as UV1642, so a wider instrument is no longer needed to explain the original failure.
The DSS2 image is resampled into the recovered plate orientation and footprint. Its photographic epochs, bands, resolution and contrast differ. Brightness and morphology need not match. It is context from the recovered WCS, not an additional independent fit check.
A clean list of 1,613 detections still contains multiple images of the same stars. The common 0, 153, 301 binned-pixel triple pattern yields 46 actual left-anchor positions. Both an all-sky run and a Polaris-assisted run recover the same near-polar field. Other displacement peaks cannot all be combined into one complete exposure sequence; arbitrary chain averages were misleading.
Center RA 198.60907774°, Dec +88.71094609°. After excluding reference stars near solver inputs, 530 additional associations have median/p90 residuals 1.782/3.257 native pixels. Shifted controls yield 36, 32, 56, 39, 37, 36 associations.
This is a separate coordinate frame for one sky/exposure component. Residuals use a finite association gate and no historical proper-motion propagation; they validate location rather than isolate glass distortion.
Across these scans, repeated photographic images need not imply the same mechanism. Shutter timing, guiding offsets, objective optics and different pointings can leave related patterns. Establish consistent component membership before fitting a smooth warp. No result here isolates glass deformation from telescope optics, emulsion, scanner geometry and centroid bias.
The location was checked against a finer reference index after excluding catalog positions near every solver input. There are 530 additional matches, with median/p90 residuals of 1.782/3.257 native pixels; six displaced controls give 32–56 matches. The 4-native-pixel association gate truncates these residuals. This validates the sky location; it does not certify a fitted distortion correction.
The downloadable WCS maps the selected left-anchor exposure component. It neither co-registers every repeated stellar image nor supplies a new polynomial or physical glass correction. No rectified UV1693 image is claimed.
Select a numbered pin or a note. Locations are editorial review pointers, not measured confidence contours; plate-wide limitations also apply.
The anchor WCS does not register all repeated images. Several offset families do not form one complete sequence.
The Polaris and calibration notes are compatible with the recovered field, but do not establish the exact number or order of shutter operations.
Additional reference matches validate the location through a finite association gate. They are not a held-out distortion-model experiment.
Use the recovered field to assign each photographic image to a consistent exposure component, propagate reference positions to the plate epoch and reserve independent stars before fitting distortion.
UV1693 is now an identified near-polar field with strong additional reference support. The earlier unresolved result and wider-telescope explanation are superseded; exposure decomposition and distortion remain separate unfinished measurements.
All scientific numbers are snapshots of the saved analysis products. The original 16-bit scans remain the measurement source. JPEG derivatives, contrast stretching and masked previews are inspection tools; do not derive photographic density or absolute response from their appearance.
