This upload contains the full integrated manuscript, tables, and supplementary figures for the study “Independent Cross-Observatory Analysis of the 3I/ATLAS Perihelion Event (29–31 October 2025).” The document synthesizes cross-observatory data from NASA, ESA, JAXA, and NOAA archives and integrates light-curve anomalies, spectral emissions, solar-wind interactions, perihelion timing irregularities, and non-gravitational acceleration profiles into a unified analysis. This version includes:• The full master manuscript (PDF)• Supplementary Tables (PDF)• Supplementary Figures (PDF) The work provides a structured methods section, dataset provenance, falsification pathways, and analysis of perihelion multi-instrument inconsistencies. Author: Julius Nicholson (ORCID: 0009-0003-1662-0669)