This version provides the fully revised Volume I (v7) analytical manuscript for Independent Cross-Observatory Analysis of the 3I/ATLAS Perihelion Event (29–31 October 2025). It integrates NASA, ESA, JAXA, and NOAA archival datasets with independent correlation analysis, multi-instrument cross-validation, timing-offset reconstruction, and structured falsification modeling of perihelion-window anomalies. The update includes expanded brightness-modulation tracking, solar-wind boundary conditions, reflectance-curve harmonization, and refined non-gravitational acceleration models derived from SOHO, SDO, Hinode, Parker Solar Probe, and SWPC datasets. This version introduces a complete systematic uncertainty budget, a statistical independence analysis, and a unified model for observed perihelion deviations. This upload contains: • Full Master Manuscript (PDF) • Supplementary Tables (PDF) • Supplementary Figures (PDF) Author: Julius Nicholson (ORCID: 0009-0003-1662-0669)

We present Volume I (v7) of an independent cross-observatory analysis of the 3I/ATLAS perihelion event (29–31 October 2025). Using multi-instrument datasets from NASA, ESA, JAXA, and NOAA archives, we evaluate reported timing offsets, light-curve anomalies, non-gravitational acceleration signatures, and instrument-specific inconsistencies. We introduce a unified model reconciling LASCO C2/C3 brightness modulation, OMNI solar-wind variations, Hinode X-ray flux irregularities, and SDO extreme-ultraviolet (EUV) fluctuations. Our results emphasize dataset provenance, reproducible falsification pathways, and identification of statistically significant deviations not attributable to calibration artifacts or thermal-outgassing assumptions. The analysis demonstrates strong cross-instrument correlation of short-interval perturbations during peak perihelion and provides the foundation for expanded modeling in Volume II.

Methods summary: Multi-observatory datasets were integrated across NASA SOHO/SDO, ESA Solar Orbiter, JAXA Hinode, NASA/NOAA OMNI/SPWC, and LASCO C2/C3 frames. Analysis includes 1-minute solar-wind telemetry, IMF vector alignment, proton-density gradients, emission-spectrum harmonization, perihelion timing irregularities, cross-instrument brightness-modulation comparisons, reflectance-curve normalization, and reconstruction of non-gravitational acceleration terms using independent falsification pathways for each observation window (29–31 Oct 2025).

Methods notes document cross-instrument alignment across NASA SOHO, SDO, ESA Solar Orbiter, JAXA Hinode, Parker Solar Probe, and NOAA SWPC datasets. Included analyses: X-ray flux drift, proton-density variation, magnetic-field vector shifts, IMF discontinuities, emission-spectrum offsets, and reflectance-curve comparison across perihelion interval (29–31 Oct 2025). Notes include validation steps, dataset provenance, and structured error-elimination pathways.