GLASS / PLATE LAB
Specimen 11 / 14 · collaborator edition

OP967

A second spectral grid for an eventual calibrated comparison.

Calibration specimen

Repeated spectral records yield numerical profiles, and five central-row tracks now support a provisional Balmer-reference wavelength scale with unused-line checks.

Original scan
6,108 × 4,931 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?

A companion spectral plate, with five provisional Balmer-reference scales.

Five central-row profiles independently show the same Balmer-series pattern as OP966. Their line positions provide a useful provisional reference scale, with unused-line checks below. The written settings, photographic response and source identity still require verification before comparing absolute intensities across plates.

Resolved spectral structure

The records show repeated transverse features. Five central-row tracks have provisional Balmer-reference coordinates below; all other extracted tracks retain scan-pixel coordinates.

A consecutive date, with protected signal

The margin appears to read “OP 967” and “July 26/27 1950”, consistent with a following-night record rather than proof of the same settings. The mask was narrowed after an initial pass confused photographic bars with ink. The main grid is protected; labels remain candidate annotations.

The central crop retains the graded photographic bars for comparison with OP966.
The transformed right-margin crop preserves metadata clues; no uncertain values are promoted into calibration constants.
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 1.22% of this scan (367,543 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 238,009 to 367,543 pixels (1.54×). The photographic remainder uses a separate 3-pixel exclusion margin, covering 2.15% 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 celestial solution is claimed. The photographic grid requires an experiment-specific calibration model rather than a star-field WCS.

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.
03a /

Recover the embedded spectral profiles.

The photographic streaks contain transverse band structure. These are recoverable spectral records rather than featureless bars: the extraction measures selected tracks across the graded grid, including both bright and faint examples. Their exposure interpretation remains open; a selected subset has provisional Balmer-reference scales below.

43 selected tracks are plotted below. Final measurements use original 16-bit TIFF values, one sample per native Y pixel, with linear interpolation across each traced aperture. The average of two adjacent sidebands estimates local background. Final profiles are not smoothed.

The ordinate is scanner response after background subtraction. It is not calibrated flux or optical density, and the abscissa is original scan Y, not wavelength. Normalized comparisons cannot establish sensitivity, line strength or exposure linearity without the scanner/emulsion response and wavelength references.

Cyan aperture boundaries locate the sampled tracks on the original scan. IDs connect the image to individual plots and CSV files. Sidebands lie outside each aperture; nearby blemishes and low-contrast traces still require inspection.
Download this profile CSV ↓
row 1 · 302 native samples · aperture ±11 px
Top: straightened image strip; cyan lines bound the extraction aperture. Middle: background-subtracted response. Bottom: aperture mean and adjacent background. Nearby blemishes and poorly exposed intervals still require inspection.
Selected profiles shown together, each independently divided by its own 95th percentile absolute response. Native pixel positions are retained. This is a pattern comparison, not a common wavelength axis or a calibrated intensity comparison.

What would make these physical spectra?

Identify known lines or a comparison source, fit wavelength as a function of scan position, test that fit on unused lines, and establish which tracks share the same instrumental setting. Then assess photographic density, saturation, scattered light and scanner response before interpreting line ratios. The present CSVs preserve the measured scanner values for that next analysis.

03c /

Exposure-aware reassessment.

A companion spectral plate, with five provisional Balmer-reference scales.

Five central-row profiles independently show the same Balmer-series pattern as OP966. Their line positions provide a useful provisional reference scale, with unused-line checks below. The written settings, photographic response and source identity still require verification before comparing absolute intensities across plates.

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.

03d /

A provisional hydrogen wavelength ruler.

The selected spectra show five converging features consistent with consecutive Balmer lines: Hγ 4340.462 Å, Hδ 4101.740 Å, Hε 3970.072 Å, H8 3889.049 Å and H9 3835.384 Å (NIST air references). They span violet and near ultraviolet; telescope UV capability alone does not identify a plate’s bandpass.

We use Y = A + B(4000/λ)². Hγ and Hδ determine the two anchor parameters; the other three features are unused checks. Alternative consecutive Balmer assignments starting at upper levels n=3…8 were tested, and n=5 gives the best check residuals for all ten selected OP tracks. The supplied final scale refits all five features after those checks.

Five selected tracks on their Balmer-reference air-wavelength scales. Individual normalization is for pattern comparison, not line-flux measurement. Gray regions are outside the checked reference interval.
Unused-line checks and calibrated profiles
Track Unused-line RMS / native px Plot Data
S17 0.503 Open plot ↗ CSV ↓
S18 0.319 Open plot ↗ CSV ↓
S19 0.718 Open plot ↗ CSV ↓
S20 0.489 Open plot ↗ CSV ↓
S21 0.249 Open plot ↗ CSV ↓

Redshift is still a separate measurement.

A common Doppler shift is absorbed by the fitted coefficient B when stellar Balmer lines themselves define the wavelength ruler. These are Balmer-referenced rest-line coordinates, not independently calibrated observed wavelengths. No redshift or radial velocity is measured. A stationary comparison reference or an independently established instrumental dispersion scale is required to break that degeneracy.

The checked interval is 3835.384–4340.462 Å. Outside it, the model is extrapolation. Scanner response, saturation, photographic density, blending and line widths remain uncalibrated. Reported widths combine instrumental, stellar and photographic effects; they are not a pure resolving-power measurement. No calibration is assigned to the remaining raw tracks merely by proximity.

04 /

Distortion: what is measured, and what is not.

Five selected tracks support the consecutive Balmer assignment Hγ through H9. Hγ and Hδ anchor a two-parameter inverse-square dispersion model; the other three lines test it. Across both OP plates, unused-line RMS spans 0.25–1.32 native pixels. The delivered reference scale is then refitted to all five lines.

This is a provisional Balmer-referenced air-wavelength coordinate over 3835–4340 Å, not an independently determined observed-frame wavelength or flux scale. Fitting stellar lines to rest references absorbs a common Doppler shift into the dispersion coefficient: redshift and radial velocity remain unmeasured.

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.

01Grid identity

The relationship of this sequence to OP966 is unconfirmed, including any changed exposure or processing conditions.

02Signal-label contacts

Some short fragments near photographic bars remain ambiguous. The binary selection should be reviewed before quantitative extraction.

03Written schedule

The margin may establish pairing and units once it is transcribed and checked against records.

The next useful experiment

Obtain an independent comparison-lamp or stationary reference, verify the spectral source and exposure schedule, then test observed wavelengths and photographic response.

Present conclusion

Five Balmer-referenced profiles per plate are supplied alongside the original pixel-coordinate extractions. Wavelength interpretation is provisional; flux calibration and redshift are unresolved.

06 /

An inspectable record for the next collaborator.

Source filename
OP967.tif
Native dimensions
6108 × 4931 pixels; I;16
Original SHA-256
c4d3d4e319c4f3c872a12e259c5d40a61958bece5b849f28253ff88054c9bea0
Display derivative
2600 × 2099 px; JPEG; no photometric calibration
Display stretch
Linear; percentile 1 = 0, percentile 99.7 = 44631; 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
← OP966R3662 →