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\@writefile{toc}{\contentsline {paragraph}{Product gaps.}{1}{section*.1}\protected@file@percent }
\@writefile{toc}{\contentsline {section}{\numberline {2}Products measured}{1}{section.2}\protected@file@percent }
\@writefile{toc}{\contentsline {section}{\numberline {3}Overview}{2}{section.3}\protected@file@percent }
\@writefile{lof}{\contentsline {figure}{\numberline {1}{\ignorespaces Overview of sgrb2. Left: source surface density in 72$\times $72 sky cells for F466N, the filter with the most detections. Centre: the sky coverage of each filter, sub-sampled. Right: number counts per filter; the peak of each curve is the turnover magnitude, the practical completeness limit beyond which the counts are set by detectability rather than by the stellar population.}}{2}{figure.1}\protected@file@percent }
\newlabel{fig:D1_overview}{{1}{2}{Overview of sgrb2. Left: source surface density in 72$\times $72 sky cells for F466N, the filter with the most detections. Centre: the sky coverage of each filter, sub-sampled. Right: number counts per filter; the peak of each curve is the turnover magnitude, the practical completeness limit beyond which the counts are set by detectability rather than by the stellar population}{figure.1}{}}
\@writefile{toc}{\contentsline {section}{\numberline {4}Astrometry}{2}{section.4}\protected@file@percent }
\@writefile{toc}{\contentsline {paragraph}{How the offsets were measured.}{2}{section*.2}\protected@file@percent }
\@writefile{toc}{\contentsline {subsection}{\numberline {4.1}Repeatability}{3}{subsection.4.1}\protected@file@percent }
\@writefile{toc}{\contentsline {subsection}{\numberline {4.2}Absolute tie}{3}{subsection.4.2}\protected@file@percent }
\@writefile{toc}{\contentsline {section}{\numberline {5}Photometry}{3}{section.5}\protected@file@percent }
\@writefile{toc}{\contentsline {subsection}{\numberline {5.1}Precision and depth}{3}{subsection.5.1}\protected@file@percent }
\@writefile{lof}{\contentsline {figure}{\numberline {2}{\ignorespaces Internal astrometry of sgrb2. Per filter: the scatter of the individual-exposure centroids about the merged position, against brightness; greyscale is source density, the coloured line and band are the running median and 16--84th percentile, and the dotted line marks the bright-decile floor quoted in the panel. The final panel is the median separation between the same stars measured independently in each pair of filters; only sources independently detected in both bands are counted, since a forced or seeded position imported from another band would measure the merge radius rather than the astrometry.}}{4}{figure.2}\protected@file@percent }
\newlabel{fig:D2_astrometry_internal}{{2}{4}{Internal astrometry of sgrb2. Per filter: the scatter of the individual-exposure centroids about the merged position, against brightness; greyscale is source density, the coloured line and band are the running median and 16--84th percentile, and the dotted line marks the bright-decile floor quoted in the panel. The final panel is the median separation between the same stars measured independently in each pair of filters; only sources independently detected in both bands are counted, since a forced or seeded position imported from another band would measure the merge radius rather than the astrometry}{figure.2}{}}
\@writefile{lof}{\contentsline {figure}{\numberline {3}{\ignorespaces Absolute astrometry of sgrb2 against its registered reference catalogue. Each per-filter panel maps the offset-histogram tie on a 12$\times $12 tile grid (arrows, exaggerated; colour is the per-tile peak contrast), with the whole-field bulk tie quoted in the corner. Grey crosses mark tiles whose tie was only found by widening the search window and whose offset is therefore not trustworthy. The final panel collects the bulk ties. Offsets are measured by offset-histogram stacking, which is immune to the nearest-neighbour pairing collapse that a median against a dense reference suffers; the per-tile map is shown because a bulk offset near zero does not by itself mean the field is registered.}}{5}{figure.3}\protected@file@percent }
\newlabel{fig:D3_astrometry_absolute}{{3}{5}{Absolute astrometry of sgrb2 against its registered reference catalogue. Each per-filter panel maps the offset-histogram tie on a 12$\times $12 tile grid (arrows, exaggerated; colour is the per-tile peak contrast), with the whole-field bulk tie quoted in the corner. Grey crosses mark tiles whose tie was only found by widening the search window and whose offset is therefore not trustworthy. The final panel collects the bulk ties. Offsets are measured by offset-histogram stacking, which is immune to the nearest-neighbour pairing collapse that a median against a dense reference suffers; the per-tile map is shown because a bulk offset near zero does not by itself mean the field is registered}{figure.3}{}}
\@writefile{lof}{\contentsline {figure}{\numberline {4}{\ignorespaces Photometric precision of sgrb2. Greyscale is source density; the solid line is the running median of the fitter's formal uncertainty $\sigma _F/F$ and the dashed line the same quantity propagated from the per-exposure scatter. The dotted horizontal line is $\sigma _F/F = 0.2$, and where the median crosses it is quoted as the $5\sigma $ depth. A propagated-to-formal ratio above unity means the exposures disagree by more than the fit covariance predicts.}}{6}{figure.4}\protected@file@percent }
\newlabel{fig:D4_photometry_precision}{{4}{6}{Photometric precision of sgrb2. Greyscale is source density; the solid line is the running median of the fitter's formal uncertainty $\sigma _F/F$ and the dashed line the same quantity propagated from the per-exposure scatter. The dotted horizontal line is $\sigma _F/F = 0.2$, and where the median crosses it is quoted as the $5\sigma $ depth. A propagated-to-formal ratio above unity means the exposures disagree by more than the fit covariance predicts}{figure.4}{}}
\@writefile{toc}{\contentsline {subsection}{\numberline {5.2}Fit quality}{6}{subsection.5.2}\protected@file@percent }
\@writefile{toc}{\contentsline {subsection}{\numberline {5.3}Colour diagrams}{6}{subsection.5.3}\protected@file@percent }
\@writefile{lof}{\contentsline {figure}{\numberline {5}{\ignorespaces PSF-fit quality for sgrb2. Per filter, the normalised fit residual qfit against brightness (greyscale: source density; line: running median; dotted: the qfit\,=\,0.2 vetting threshold). The final panel is the fraction of each filter's catalogue touched by the saturation-handling paths: flagged saturated, core-replaced, rejected by the saturated-star gate, and clip-corrected.}}{7}{figure.5}\protected@file@percent }
\newlabel{fig:D5_photometry_quality}{{5}{7}{PSF-fit quality for sgrb2. Per filter, the normalised fit residual qfit against brightness (greyscale: source density; line: running median; dotted: the qfit\,=\,0.2 vetting threshold). The final panel is the fraction of each filter's catalogue touched by the saturation-handling paths: flagged saturated, core-replaced, rejected by the saturated-star gate, and clip-corrected}{figure.5}{}}
\@writefile{lof}{\contentsline {figure}{\numberline {6}{\ignorespaces Colour diagrams for sgrb2, from the stage-m7 cross-band merge, in Vega magnitudes. These are differential between filters and so respond to systematics that per-filter statistics cannot see: a zero-point error shifts a sequence bodily, a saturation-correction discontinuity breaks it at a specific magnitude, and a filter-dependent background error tilts it.}}{8}{figure.6}\protected@file@percent }
\newlabel{fig:D8_color_diagrams}{{6}{8}{Colour diagrams for sgrb2, from the stage-m7 cross-band merge, in Vega magnitudes. These are differential between filters and so respond to systematics that per-filter statistics cannot see: a zero-point error shifts a sequence bodily, a saturation-correction discontinuity breaks it at a specific magnitude, and a filter-dependent background error tilts it}{figure.6}{}}
\@writefile{toc}{\contentsline {section}{\numberline {6}Background and diffuse emission}{8}{section.6}\protected@file@percent }
\@writefile{toc}{\contentsline {paragraph}{Two different quantities.}{8}{section*.3}\protected@file@percent }
\@writefile{toc}{\contentsline {subsection}{\numberline {6.1}Distributions}{8}{subsection.6.1}\protected@file@percent }
\@writefile{toc}{\contentsline {subsection}{\numberline {6.2}Spatial structure}{9}{subsection.6.2}\protected@file@percent }
\@writefile{toc}{\contentsline {section}{\numberline {7}Implications}{9}{section.7}\protected@file@percent }
\@writefile{toc}{\contentsline {section}{\numberline {8}Reproducibility}{9}{section.8}\protected@file@percent }
\@writefile{lof}{\contentsline {figure}{\numberline {7}{\ignorespaces Background estimators for sgrb2. First panel: the distribution of the annulus background handed to the fitter (solid) and, where available, the residual-footprint background (dashed). Remaining panels: the running median of each against brightness, with the 16--84th percentile band for the annulus estimator; the vertical dotted line marks the brightest 1 per cent, where a star's own wings begin to enter its own background aperture. The residual-footprint column is present for 0 of 12 filters; it was added in 2026-07, so catalogues produced before then carry only the annulus estimator.}}{10}{figure.7}\protected@file@percent }
\newlabel{fig:D6_background_distributions}{{7}{10}{Background estimators for sgrb2. First panel: the distribution of the annulus background handed to the fitter (solid) and, where available, the residual-footprint background (dashed). Remaining panels: the running median of each against brightness, with the 16--84th percentile band for the annulus estimator; the vertical dotted line marks the brightest 1 per cent, where a star's own wings begin to enter its own background aperture. The residual-footprint column is present for 0 of 12 filters; it was added in 2026-07, so catalogues produced before then carry only the annulus estimator}{figure.7}{}}
\@writefile{lof}{\contentsline {figure}{\numberline {8}{\ignorespaces Spatial background structure in sgrb2. Left column: the median per-source background in 56$\times $56 sky cells -- a map of the diffuse emission built entirely from the star catalogue. Right column: the same per-source value against the surface brightness of the drizzled mosaic sampled at that source's position, with the running median in red and the Spearman rank correlation quoted. A high rank correlation is the evidence that the per-source background is measuring the astrophysical extended emission rather than a fitting artefact.}}{11}{figure.8}\protected@file@percent }
\newlabel{fig:D7_background_spatial}{{8}{11}{Spatial background structure in sgrb2. Left column: the median per-source background in 56$\times $56 sky cells -- a map of the diffuse emission built entirely from the star catalogue. Right column: the same per-source value against the surface brightness of the drizzled mosaic sampled at that source's position, with the running median in red and the Spearman rank correlation quoted. A high rank correlation is the evidence that the per-source background is measuring the astrophysical extended emission rather than a fitting artefact}{figure.8}{}}
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