3I/ATLAS Photometric–Chromatic Anomaly (2025)

Version Summary

This version introduces automated peak detection for optical acceleration, corrected Δv timing, and a new station-level consistency test for evaluating late-November photometric deviations. The MPC dataset is now extended through 2025-12-01, and Δv(t) reconstructions, acceleration plots, and IAI components have been regenerated accordingly. Newly published UVES spectroscopy is incorporated via a compositional anomaly axis (Aₓ) based on Ni/Fe enrichment, expanding the Interstellar Anomaly Index. Station-by-station validation confirms that the November 22–25 and November 28–December 1 features are noise rather than physical acceleration events. All data products, figures, and analysis scripts are cryptographically timestamped for full reproducibility.

🧾 Version 2.6 Detailed Notes (Fully Expanded)

Major Improvements

• Automated optical peak detection

• Corrected Δv timing

• New colour–brightness timeline

• Updated post-perihelion fading analysis (to Dec 1)

• Station-level consistency tests (two windows)

• Ni/Fe anomaly integrated into IAI

• Regenerated Δv figures, including overlays

• New figures for station-level noise discrimination

• All scripts updated for auto-detection of colour files

• Manifest updated with all new files + integrity proofs

Data Coverage

• Observations: 4,960 MPC records

• Time span: 2025-05-08 → 2025-12-01

• Nights with valid photometry: ≈ 130

• Multi-filter colour coverage: 2025-07-01 → 2025-09-11

Noise Assessment

The two apparent late-November bumps are now conclusively identified as noise, based on:

• 29 independent stations

• No >3σ coherent deviations

• Mixed signs across stations

• Weak daily means (0.0266×10⁻³ and 0.0004×10⁻³)

• Second bump dominated by a single observatory

Forensic Reproducibility

All outputs are sealed using:

• SHA-256 checksums

• GPG signatures

• OpenTimestamps (Bitcoin)

🧩 Files Included (v2.6)

A fully updated table reflecting the structure of this version.

🧪 2. Scientific Context — Updated for v2.6

A polished, stronger, and fully accurate version reflecting the expanded dataset.

The photometric–chromatic anomaly framework developed in previous releases demonstrated that photometry alone can reveal dynamical precursors—changes in brightening rate and colour evolution—before orbital astrometry reflects non-gravitational acceleration.

Version 2.6 expands this framework significantly.

What v2.6 reveals:

• The optical-acceleration proxy continues to provide a precise chronology of activation:

  • two sharp pre-perihelion spikes (Sept 9 and Oct 2),

  • followed by a monotonic post-perihelion decline.

• Automated peak detection removes subjective human timing.

• Δv reconstruction confirms that these short-lived impulses dominate the momentum budget (90–95% of Δv).

• The colour–brightness timeline shows a clean transition to fading, with +1.5 mag dimming in the g-band.

• UVES spectroscopy introduces Ni/Fe overabundance, enabling a new compositional anomaly axis AxA_xAx.

Novel capability introduced in v2.6

The station-by-station, time-normalised validation is a major methodological advance:

• It distinguishes real physical acceleration from artefacts by checking:
  ✔ coherence across telescopes
  ✔ sign consistency
  ✔ amplitude significance
  ✔ temporal clustering

• Both late-November features fail these tests:

  • Nov 22–25: appears coherent in aggregation but not in station signals.

  • Nov 28–Dec 1: dominated by a single station (703), not physical.

Thus no third activation event is detected beyond the two major pre-perihelion impulses.

Scientific impact

Version 2.6 establishes that:

1. Photometric anomaly analysis is a robust early-warning tool for interstellar objects.

2. Δv estimates derived purely from photometry can match dynamical requirements (e.g., Loeb’s Jupiter geometry).

3. The Interstellar Anomaly Index provides a multi-axial classification across photometric, chromatic, dynamical, morphological, and compositional domains.

4. The Ni/Fe anomaly integrates compositional spectroscopy into the anomaly-scoring framework for the first time.

5. Noise discrimination using multi-station analysis becomes essential for interpreting faint post-perihelion signatures.

This combination of methods—photometry, colour indices, Δv reconstruction, anomaly quantification, and station-consistency analysis—constitutes a reproducible, instrument-independent system for assessing interstellar-object behaviour.

🔐 Verification and Reproducibility

All analytical assets are timestamped, hashed, and digitally signed.
The protect_atlas_v2_6.sh script generates a deterministic proof bundle containing:

• SHA-256 integrity manifest

• GPG signature (.asc)

• OpenTimestamps blockchain proof (.ots)

These provide verifiable provenance and cryptographic reproducibility for all datasets, figures, and analysis scripts.

Check folder manifests with the files:

📚 Suggested Citation

Gherbi, Salah-Eddin (2025).
3I/ATLAS (C/2025 N1) — ATLAS Photometric–Chromatic Anomaly (2025): Automated Peak Detection, Δv Correction, and Station-Consistency Validation (v2.6).
Zenodo. https://doi.org/10.5281/zenodo.17793630

🪶 Project Metadata

Project: 3I/ATLAS Photometric–Chromatic Anomaly Series
Scope: Independent research programme (2025 – ongoing) focused on photometric, chromatic, and dynamical diagnostics of the interstellar object 3I/ATLAS (C/2025 N1).

Author: Salah-Eddin Gherbi
Independent researcher — photometry, interstellar object analysis, planetary dynamics, anomaly quantification.

Reproducibility Pipeline:
protect_atlas_v2_6.sh — automated archival and authentication pipeline using:

• SHA-256 manifests

• GPG detached signatures

• OpenTimestamps (Bitcoin-anchored) proofs
  ensuring full temporal integrity and verifiable provenance of the dataset.

Previous Release:
v2.5 — Δv-based dynamical modelling, Interstellar Anomaly Index (IAI), extended post-perihelion evolution.

Current Release:
v2.6 — Automated Peak Detection, Δv Correction, Ni/Fe Integration & Station-Consistency Validation, extended post-perihelion evolution, updated manuscript, complete pipeline and proof bundle.

License: CC BY-NC-SA 4.0
Open for non-commercial use with attribution; derivatives permitted under identical terms.