Registration: matched compact-source occurrence

Registration: matched compact-source occurrence

11 October 2026. This is a prospective scientific protocol, distinct from the completed metadata/header checks and the closed N20/c6828 units. Its registration commit, sample and input hashes must precede retrieval of new map values or MIPSGAL source rows. No comparison has yet been read.

Question, estimand and population

Test whether catalogue-prestellar Hi-GAL clumps at 0 < distance <= 4 kpc show more compact 24-micron catalogue sources than nearby positions with comparable column, sensitivity and surrounding crowding. The primary quantity is a paired observed source-occurrence difference, not the fraction hosting protostars. Catalogue detection, physical association, novelty and birth are different claims.

The parent is every unique designation in the cached higal360clump.csv with evol_flag == 1 and finite distance in (0, 4]. This gives 19,328 entries. The historical 19,219-object E1 cohort omitted 109 of these; it is recorded as a provenance flag, not inherited as a selection rule. The cached 94,604-row clump table is itself a subset of the published catalogue. No inference to missing published objects or the full sky is permitted.

The geometric domain is 0.1 < l < 68.9 or 292.1 < l < 359.9 degrees, with |b| < 0.9 degrees. This buffer lies inside the nominal MIPSGAL disk footprint; it does not certify local coverage. Draw exactly 1,000 entries by ascending SHA-256 of matched-control-20261011: plus exact designation, with designation as tie breaker. Freeze their native coordinates, distances and historical membership in sample.csv; retain the parent, domain and omitted denominators in registration.json. Do not select by infrared flux, an old score or a known YSO match. All 1,000 requested objects remain in the readout, including failures.

Apertures and possible controls

Use a fixed 15-arcsecond radius in both arms. This is an operational aperture, not a clump boundary or a membership assertion. It avoids the conflicting beam-convolved/deconvolved descriptions of DFWHM250 and samples more than one 12-arcsecond PPMAP resolution element. Catalogue-source centres count if their great-circle separation is <= 15 arcseconds; there is no displacement tuning.

Each target has exactly 24 possible controls: offsets of 120, 180 and 240 arcseconds at bearings 0, 45, …, 315 degrees, measured east of Galactic north using spherical geometry. Reject centres outside the registered domain or within 45 arcseconds of any of the 94,604 cached Hi-GAL centres. This fixed exclusion keeps a 15-arcsecond measurement aperture outside a 30-arcsecond catalogue-centre mask; it does not guarantee the absence of an uncatalogued clump. Do not add farther controls after seeing failures. Save every rejection.

Choose one control using covariates only, before opening the on/off occurrence table. Do not rematch after inspecting central completeness or source counts. Reuse across targets is allowed and explicitly reported; it is one reason for spatial rather than source-independent uncertainty estimates.

Native measurements and column gate

Use the original PPMAP lNNN_cdens.fits and lNNN_sigdiffcdens.fits from the Cardiff archive, with their actual per-file Galactic TAN WCS, units and FITS layout. The cached 32x32 display cutouts have no demonstrated native column/uncertainty planes and cannot replace these inputs. Use nearest native pixels, retaining their indices and all duplicated indices; no super-resolution or interpolation is inferred. At overlaps choose the tile with the greatest minimum distance to its pixel edges, then lexical tile name. Unknown coverage, nonfinite/nonpositive column, unsupported WCS or incomplete transport is unknown, never zero.

Measure central column N and a fixed 13-point profile: offsets (i,j)7.5 arcsec, where i,j are integers in [-2,2] and ii+j*j <= 4, with the same spherical construction. Compare central N, profile median and profile 90th percentile (linear order-statistic interpolation) between arms. Require absolute log10 ratios <= 0.15, 0.20 and 0.20 dex respectively, with all 13 values valid.

At each surviving centre acquire all 12 differential-column uncertainty bins. Use U = sum(sigma_k), requiring every sigma finite and nonnegative and U/N <= 0.30 in both arms. This is a conservative upper bound on the standard deviation of a sum for arbitrary bin covariance, conditional on the supplied sigmas. It is not an empirical confidence bound and excludes opacity/calibration model errors. Independent-bin quadrature is not assumed.

Perform the geometry/central-column gate first. If fewer than 800 targets have any possible column-matched control, stop with independently verified insufficient evidence before acquiring source rows. Profile/uncertainty checks may only eliminate further controls. A stricter necessary gate can therefore fail without reading an infrared outcome.

Sensitivity and crowding: avoid conditioning away a source

The published MIPSGAL differential-completeness cube is derived from artificial source tests and can be reduced by a bright source already in the cell. Matching the central cube value can therefore remove the occurrence being tested. Select controls using the surrounding completeness curve and crowding, then audit central completeness without selecting a replacement.

Use native completeness-cube WCS and magnitude axes, not the nominal one-arcminute cell size. For each centre sample the surrounding curve at radii 100 and 160 arcseconds and bearings 22.5, 67.5, …, 337.5 degrees. Exclude any sample within 15 arcseconds of the target or any of its 24 possible control centres. Require at least eight remaining samples with valid native coverage. At each of the 13 exact magnitude centres 0.75, 1.25, …, 6.75, take the median completeness. All values must be in [0,1], both medians >= 0.90 and their absolute difference <= 0.05 at every magnitude. No extrapolation, missing-plane imputation or monotonic repair is allowed. Preserve missing/invalid cells.

For surrounding crowding count high-reliability mipsgalc catalogue sources with 0.75 <= MAG_24 <= 8.75 in the 90–180-arcsecond annulus, masking all 25 15-arcsecond primary apertures. Use exact spherical separations. Estimate the remaining solid-angle area with 4,096 deterministic equal-area annulus points (radial midpoint quantiles, golden-angle azimuth), applying the same masks. Require at least half the nominal area and |log10[(n_on+1)/area_on] - log10[(n_off+1)/area_off]| <= 0.20 dex. The +1 is registered smoothing, not a hidden source; catalogue crowding remains an incomplete proxy for true crowding.

Among passing controls minimise the sum of squared differences divided by the registered tolerances: central log N/0.15, profile-median log N/0.20, profile-p90 log N/0.20, crowding log density/0.20, and mean completeness-curve difference/0.05. Tie break by radius then bearing. Record all costs/covariates. Before the occurrence readout require at least 800 chosen pairs, at least 20 occupied five-degree longitude blocks, and absolute standardised mean differences <= 0.10 for each log-column feature, crowding and mean surrounding completeness. Standardisation uses the pooled marginal sample SD; equal constant features pass, unequal constants fail. Missing values cannot pass balance.

Central completeness is then evaluated at each arm, using the same 13 magnitude centres. The primary cohort additionally requires both central curves >= 0.90 and pairwise differences <= 0.10 at every plane, with no rematching. It must retain at least 800 pairs/20 blocks and pass the same covariate balance checks. This produces an explicitly conditional common-sensitivity estimand. Report attrition by arm and a mandatory result on the selected surrounding-only cohort, without this central gate. Disagreement or unsupported sensitivity prevents a robust positive/null conclusion. Neither completeness gate certifies 90% completeness for all catalogue quality cuts or for embedded protostars.

Outcome, uncertainty and decisions

Use the IRSA high-reliability mipsgalc product, rather than mixing it with the lower-reliability mipsgala archive. The product’s published selection is part of the estimand. Keep exact mipsgal_name and cntr strings, coordinates, MAG_24, flux/error, FWHM and edge/confusion metadata; do not impose an invented shape cut or require an external young-star counterpart. Do not interpret a completeness curve as validation of this full quality selection.

For each retained aperture, Y is one if it contains at least one catalogue source with 0.75 <= MAG_24 <= 6.75, otherwise zero only with verified complete query support. Delta is mean(Y_on - Y_off), in percentage points. Also report source counts and paired discordances, but neither is a substitute primary.

Use 20,000 bootstrap resamples of the occupied five-degree Galactic-longitude blocks, with replacement, seed 20261011; calculate each resample as the ratio of summed paired differences to summed pairs. Report the 2.5/97.5 percentile interval. This represents variation across the sampled spatial blocks, not systematic catalogue/model uncertainty or independence of every clump. Disclose overlapping apertures and repeated controls. Repeat with ten-degree blocks as a mandatory dependence diagnostic, requiring >= 10 occupied blocks.

Mandatory diagnostics also use (a) the surrounding-only cohort and (b) a stricter column cohort with |Delta log10 N| + (U_on/N_on + U_off/N_off)/ln(10) <= 0.15 dex. The latter requires >= 300 pairs and >= 10 five-degree blocks. Freeze these diagnostics now; do not search aperture, flux or colour thresholds.

A supported positive requires primary interval lower endpoint > 0 and every mandatory diagnostic supported with a positive interval lower endpoint. A precise null requires every supported primary/diagnostic interval wholly inside [-3,+3] percentage points. An interval wholly below zero refutes a positive excess and is reported as a deficit, not equality. Otherwise report insufficient evidence for the registered positive/precise-null decision, including estimates and intervals when supported. Missing coverage or failed matching yields insufficient evidence with exact failure denominators.

For the full requested 1,000 objects report the identification bounds obtained by assigning each unmeasured paired difference any value in [-1,+1]; these are worst-case missingness bounds, not sampling intervals. Do not generalise a selected-cohort excess to all 19,328 clumps. No birth, lifetime, calibrated class-probability, population precision or recall follows from this test.

Only after a supported positive prepare up to 20 source-specific follow-up records from primary on-aperture sources. Rank by separation/15 arcsec, then MAG_24, then exact source name. Preserve all clump alternatives, duplicate source appearances, measured source metadata, local projected density and published astrometric limitations. Proximity/density are not an ownership probability. Known-reference/novelty status stays unknown unless separately verified; a catalogue source is neither a newly discovered star nor a birth.

Frozen acquisition, storage and stopping limits

Reuse the verified archive listing and three native headers. No all-sky source download, full 95-MiB uncertainty cube, image gallery, new survey or ML training. Only these public endpoints/products are allowed: Cardiff PPMAP native column and uncertainty files; IRSA MIPSGAL native completeness cubes and TAP mipsgalc. Use public GET queries over occupied two-degree longitude bins padded by 0.15 degrees and |b| <= 1.05, with the registered magnitude range. No coordinate file upload or E121 action. Request all rows within each frozen bound, reject truncation, and deduplicate overlapping queries only when native fields agree.

Native image access uses verified FITS headers and bounded exact byte ranges; reject whole-file responses to range requests before reading their bodies. At most 100 ranges per request, 64 KiB partial response, three 2,880-byte header blocks per file. Individual completeness cubes may be read whole only if <= 512 KiB. TAP responses <= 4 MiB and 100,000 rows each. Total limits: 8,000 HTTP requests, 512 MiB received body bytes, 30 minutes acquisition execution, one CPU thread, 64 MiB new scientific outputs and >= 5 GiB free before each request. Exact responses are compressed in one local database; retain all scientific prefixes and hash inventories. Hash-bound evidence is never temporary cleanup. Unsupported byte ranges, changed resources, transport failure, exhausted caps or lost disk reserve stop acquisition without an automatic retry or alternative route. A stopped acquisition cannot certify an absence or an excess.

The dependency runtime is separately budgeted at <= 250 MiB installed plus 100 MiB download/build peak, using only native Python/numerical/WCS/testing packages needed for this study. No GPU runtime. This documented setup estimate does not increase the 64-MiB scientific-output cap. Offline processing and independent verification each have a 30-minute execution cap and one thread. Freeze generation/analysis code before comparison; test geometric boundaries, WCS/range decoding, unknown handling, spatial uncertainty and central-gate selection on controlled fixtures. Independently regenerate sample membership, native measurements, matches and headline arithmetic from frozen raw inputs.

Commit the registration first, then implementation/controls, then independently verified scientific readout. No history rewrite, N20/c6828 restart, E29–E160 continuation or restricted Atlas/E155/E121 action. Publish actual terminal evidence separately from the already published program; logistics are not results.

Sources and known limitations

Cached Hi-GAL coverage is incomplete; PPMAP calibration/dust assumptions, coarse cells, catalogue incompleteness and unobserved environmental variables remain. A matched observational excess supports targeted follow-up rather than causal attribution to hidden protostars. Spatial bootstrap intervals cannot remove these limitations.