GLASS / PLATE LAB
Specimen 14 / 14 · collaborator edition

UV960

Five broad photographic disks within an illuminated field.

Calibration specimen

The dominant structure resembles a repeated focus or exposure test. The broad disks are photographic content and are deliberately excluded from the written annotation selection.

Original scan
6,162 × 4,951 px
Source data
16-bit TIFF
Angular scale
Not established
Sky footprint
Not established
01Complete scan, with its stored orientation retained. Display derivative: recorded 1st–99.7th percentile linear stretch, 8-bit JPEG, reduced for sharing. Click any inspection image to enlarge; click again inside the viewer for its native display pixels.
01 /

What is photographic, and what is written?

Broad target disks; their physical meaning remains open.

Several extended images and an apparent 7/8 October 1949 date suggest a deliberate target or focus study. Their dimensions are measurable in scan pixels, but neither a sky identity nor angular or focal units have been established. Repeated disks alone do not distinguish focus changes, exposure changes and optical structure.

A repeated circular subject

Five broad circular images sit within a larger illuminated circular field. A focus or exposure sequence is a working visual interpretation, not a confirmed object identification.

A separate written margin

The right margin appears to read “1949 Oct 7/8”. That image-based date extends the apparent collection chronology well beyond the initial circa-1930 description. A shape-only segmentation could confuse disk rims with strokes; inspected regions keep the disks out of the ink selection.

The photographic crop shows the broad disks and their surrounding illumination.
The right margin is transformed for reading. Disk edges are protected from the candidate ink mask.
02 /

Separate the observed layers.

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 1.69% of this scan (514,341 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.

Original scan with candidate annotation selection in cyan
Cyan shows the expanded exclusion area, including edge padding. Move the slider to inspect boundaries and incidental selections.

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.

Annotation revision 2

This revision recovers short letter fragments, round digits and inspected dark marks, with broader writing regions. The stroke selection grows from 146,012 to 514,341 pixels (3.52×). The photographic remainder uses a separate 3-pixel exclusion margin, covering 3.57% 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.

Previous photographic remainder at left; revised remainder at right. Black pixels are excluded, not restored sky. Both panels show the same scan. The native stroke and exclusion masks are supplied separately.
Previous mask ←→ Revised exclusion
Photographic remainder using expanded exclusion maskPrevious photographic remainder revealed at left
03 /

What the search can establish.

No direct astrometric field solution is claimed. There is no basis here to call the disks planets, moons or distinct stars, or to infer a focal length from their scan sizes.

No justified sky position is available for this specimen. A catalog image would imply a location the evidence has not established, so none is presented.
03c /

Exposure-aware reassessment.

Broad target disks; their physical meaning remains open.

Several extended images and an apparent 7/8 October 1949 date suggest a deliberate target or focus study. Their dimensions are measurable in scan pixels, but neither a sky identity nor angular or focal units have been established. Repeated disks alone do not distinguish focus changes, exposure changes and optical structure.

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.

04 /

Distortion: what is measured, and what is not.

The disk sequence can support comparisons of radial profiles and sharpness in scan pixels. Turning those differences into physical focus, exposure or angular units requires observing metadata and a known imaging response.

The delivered layers isolate candidate margin writing. They do not remove or flatten the circular photographic field, and no geometric distortion correction has been inferred.

No distortion map is drawn for this plate. The absence of a fitted map records an evidence limit; it does not assert that the glass or optical system is undistorted.
05 /

Where the remaining questions live.

Review locations on the original scan

Select a numbered pin or a note. Locations are editorial review pointers, not measured confidence contours; plate-wide limitations also apply.

01Broad photographic disks

Their identity and the variable changed between exposures remain unverified.

02Illuminated field boundary

Vignetting, illumination and image support are not independently calibrated; this boundary is not a measured distortion contour.

03Written margin

Faint or overlapping strokes may be incomplete in the extracted layer. The margin is a useful target for historical transcription.

The next useful experiment

Measure normalized radial profiles, disk diameters and background illumination on the original scan; compare them only after the focus or exposure sequence is established from the notes.

Present conclusion

Preserve the disks as signal. The useful next result is a calibrated profile comparison, not a forced celestial solution.

06 /

An inspectable record for the next collaborator.

Source filename
UV960.tif
Native dimensions
6162 × 4951 pixels; I;16
Original SHA-256
d97c32759407c7993b409d34c785a6838f99e10521c6168bb9bc755784b7ebd8
Display derivative
2600 × 2089 px; JPEG; no photometric calibration
Display stretch
Linear; percentile 1 = 2, percentile 99.7 = 53065; clipped to 8 bits
Detail crops
Fractional original-coordinate boxes recorded in source.json. Long margins are rotated and mirrored for reading.
Layer coordinates
Native original scan size, except explicitly labeled rectified UV1642 writing
Original TIFF
Not included in this portable report; retained separately, unchanged
Analysis method
Local Astrometry.net 0.98; inspected source selection, exposure grouping where necessary; saved reference associations and internal held-out checks
Snapshot date
27 October 2026

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.

  1. Astrometry.net: local plate-solving software
  2. Bundled methods, limitations and handoff notes
← R3663Return to all plates →