Surveys→ SDSS

SDSS DR18

Sloan Digital Sky Survey Data Release 18. Three-threshold disclosure: 77,905 (cross-transfer top-1% continuity baseline), 19,253 (native top-1% S>=0.2051), 12 (native S>5 field-defining threshold). Domain shift confirmed: DESI-trained autoencoder sees SDSS-specific spectral types (ultra-cool dwarfs, M7/T2/L3) as anomalous.

QC CAUTION

2.3M spectra

77,905 anomalies (3.4%)

Optical spectroscopy (3800-9200 Å)

Readiness

QC CAUTION

SDSS

Cross-transfer baseline (77,905 at S>=0.1060). Path-C native retrain (gate-PASS val_loss=0.0311) yields only 12 sources at S>5 — a ~6500x reduction confirming domain shift. Use 77,905 for cross-survey rate comparison; use 12 for purity; use 19,253 (top-1% native, S>=0.2051) for SIMBAD novelty pool.

Cost~$10

Runtime~2.8h

Sources2.3M spectra

Anomalies77,905

Rate3.4%

BandOptical

Key Findings

Results that define how this survey should be used in the paper set.

0177,905 cross-transfer anomalies (domain-shift inflation vs DESI)
02Path-C native retrain: only 12 sources at S>5 (~6500x reduction)
03Native top-1% (19,253 at S>=0.2051) is SIMBAD novelty pool
04Ultra-cool dwarfs (M7, T2, L3) dominate cross-transfer catalog
053 SDSS × DESI 5-arcsec positional coincidences

Pipeline

Model	DESI BigAE transfer (cross-transfer baseline) + native BigAE retrain (val_loss=0.0311)
Wavelength	Optical spectroscopy (3800-9200 Å)
Cost	~$10
Runtime	~2.8h

Top Anomalies

Rank	RA	Dec	Score	Type
#1	0.0deg	0.0deg	194532737024.00	Score explosion (domain shift)

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