GLASS / PLATE LAB
Specimen 07 / 14 · collaborator edition

UV1753

A repeated target sequence, with too little independent sky.

Unresolved field

The visible structure is dominated by a sparse photographic ladder and extensive writing. A useful next analysis is exposure morphology and historical metadata rather than a speculative sky warp.

Original scan
4,877 × 6,060 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?

Repeated target images favor a focus experiment; no field solution.

The apparent Vega label, date 5 August 1918 and focus settings accompany a structured rosette of repeated images. Those marks are compatible with deliberate focus variation. A source detector cannot safely treat the rosette points as unrelated catalog stars. Stellar identity, focal settings and exposure order still need a logbook or a recognizable background field.

A ladder of photographic images

A small number of repeated target-like images lie among labels. They may encode an exposure or calibration sequence, but the sequence meaning is not yet established.

Vega and a focus sequence in the notes

The transformed margin appears to include “UV1753”, “1918 Aug. 5”, “Vega” and “Focus”, with values near 22.08 and 42.02. These are visual readings, not an independent identification of the photographic target. The physical units and relation to the repeated images still need a logbook check.

The central crop emphasizes the repeated photographic target images.
The transformed margin makes the tentative “Vega”, “1918 Aug. 5” and focus notes readable. Their units and experiment interpretation remain open.
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 6.08% of this scan (1,796,362 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 597,849 to 1,796,362 pixels (3.00×). The photographic remainder uses a separate 3-pixel exclusion margin, covering 17.33% 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 confirmed astrometric solution was recovered. The available evidence does not support a field center, angular scale or reliable telescope assignment.

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.

Repeated target images favor a focus experiment; no field solution.

The apparent Vega label, date 5 August 1918 and focus settings accompany a structured rosette of repeated images. Those marks are compatible with deliberate focus variation. A source detector cannot safely treat the rosette points as unrelated catalog stars. Stellar identity, focal settings and exposure order still need a logbook or a recognizable background field.

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.

A distortion fit requires many independent reference positions spread across the plate. The sparse ladder supplies neither that spatial coverage nor a catalog association. Photographic size, intensity and repetition could still be measured in scan coordinates.

Only scan-coordinate annotation products are provided. No celestial WCS, catalog comparison or geometric correction has been fabricated for the empty parts of the field.

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.

01Repeated target ladder

The identity of the target and relation between exposures remain open. Multiple marks may represent repeated measurements of one object.

02Historical instructions

Written notes may encode durations or planning instructions; a logbook or careful transcription would be more informative than an unconstrained blind solve.

03Sparse sky background

The scan has insufficient confirmed reference geometry for a spatial distortion field.

The next useful experiment

Check the tentative Vega/focus reading against the plate log, then measure each photographic profile consistently and compare image width with the recorded settings. Keep saturation, physical focus units and unknown scanner response explicit.

Present conclusion

An unresolved sky identification does not make the specimen uninformative. It is a plausible calibration sequence whose quantitative interpretation needs metadata.

06 /

An inspectable record for the next collaborator.

Source filename
UV1753.tif
Native dimensions
4877 × 6060 pixels; I;16
Original SHA-256
c77cb25377bb5ce5afa0968762b40b3d138bb3a73616a180684bd565e368e48a
Display derivative
2092 × 2600 px; JPEG; no photometric calibration
Display stretch
Linear; percentile 1 = 60, percentile 99.7 = 52462; 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
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