3I/ATLAS Photometric–Chromatic Anomaly (2025)

This dataset accompanies the study “Photometric and Non-Gravitational Anomalies in the Interstellar Object 3I/ATLAS (C/2025 N1)” (Version 2.2).It contains all verified data, figures, and code supporting the detection of a pre-perihelion photometric acceleration and associated color evolution in 3I/ATLAS — the third confirmed interstellar visitor to the Solar System. Using 4 ,280 MPC photometric observations between May and October 2025, the analysis identifies a sharp optical acceleration event on 2025-09-10, approximately 50 days before perihelion, coincident with a reddening of the g–o color index (Δ ≈ +0.57 mag). These findings suggest a physical transition in the object’s surface or coma composition, although the underlying mechanism remains under investigation. All datasets, scripts, and figures are cryptographically timestamped using OpenTimestamps and signed with GPG for proof of existence and authorship.The materials are intended to enable independent reproduction, validation, and further comparative analysis of interstellar cometary activity. Contents:• Raw MPC photometry (I3.txt)• Processed CSV datasets (color indices, optical acceleration)• Python scripts and LaTeX manuscript• Figures (I3_Optical_Acceleration_Trend_v2.png, I3_Optical_Color_Correlation.png)• Blockchain-timestamped proof manifests (.ots, .asc) Author: Salah-Eddin Gherbi (Independent Researcher, UK)ORCID: 0009-0005-4017-1095License: CC BY-NC 4.0Repository: GitHub — salah-gherbi-3I_ATLAS_Anomaly_2025