The corrected extraction follows three non-crossing records through the bright lower feature. The outer patterns agree closely; the middle spectrum is different.
The two outer records share line structure; the middle record is distinct. The previous two-track model could drift between records and stopped before the conspicuous lower feature. It has been superseded by separate non-crossing specreduce traces. The mirrored lower inscription appears to read 2 August 1920. Chemistry, source identity and wavelength scale remain open.
Three independently traced records preserve their spatial identity through the full feature range. Pattern resemblance does not by itself establish wavelength, lamp chemistry or source identity.
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 4.28% of this scan (1,737,597 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 1,319,233 to 1,737,597 pixels (1.32×). The photographic remainder uses a separate 3-pixel exclusion margin, covering 8.18% 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.
This is a spectral record rather than a solved sky field. A–B–A describes the observed pattern similarity, not an established identification of the lamp or astronomical source.
Three separate records form A–B–A. Their constrained traces cannot cross into neighboring records. specreduce 1.9.0 FitTrace and fractional-pixel BoxcarExtract recover each profile with a common external two-sided Background. The previous two-track extraction is superseded: it could drift between records and omitted the lower bright feature.
The extraction now spans native Y 1264–7799, through the formerly clipped feature. Outer-record pattern correlation is 0.967 after a three-pixel Y alignment; comparisons with the middle record are 0.149 and 0.207 in the inspected line-rich interval (native Y 2202–6200). This supports the observed A–B–A arrangement without identifying the comparison material or establishing that the middle source is stellar. Native Y is retained; cross-dispersion sampling uses a bilinear rectification and a nine-pixel fractional aperture. The middle trace is extrapolated within a bounded lane where it is faint.
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.
RASCAL 0.3.11 was run on the corrected left flanking record against a NIST iron comparison-line hypothesis. This bounded exploratory trial does not establish a unique wavelength scale or an iron identification. Its candidate matches only 30 of 189 training peaks (2.22 Å training RMS). Just 7 of 48 unused peaks fall within 3 Å of an atlas line, compared with 6–12 under shifted controls. Those checks do not support accepting it. No IB5894 wavelength calibration is accepted; the middle record has not been forced onto a hydrogen model.
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.
The two outer records share line structure; the middle record is distinct. The previous two-track model could drift between records and stopped before the conspicuous lower feature. It has been superseded by separate non-crossing specreduce traces. The mirrored lower inscription appears to read 2 August 1920. Chemistry, source identity and wavelength scale remain open.
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.
Three constrained traces are extracted with specreduce 1.9.0 from original 16-bit scanner values. The previous two-trace curves are superseded. No accepted wavelength solution is available for this plate.
Tracing corrects measured cross-dispersion curvature for extraction. This is a local sampling transformation, not a celestial WCS or physical glass correction.
Select a numbered pin or a note. Locations are editorial review pointers, not measured confidence contours; plate-wide limitations also apply.
The middle spectrum is distinct and poorly exposed in some intervals. Its source is not established as stellar or as a hydrogen lamp.
The extraction now includes the conspicuous lower feature, through native Y 7799. Its wavelength and physical origin are not established.
The notes need transcription and comparison with an observing log; mask fragments do not constitute a textual reading.
Identify a comparison source or instrument setting from the plate log, then test wavelength candidates against unused lines and both flanking records.
Three physical profiles and their complete extraction recipes are ready for collaborators. Their pattern supports A–B–A, but no elemental identity, stellar classification or radial velocity is established.
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.
