UNJITR: UV/Optical Nonlinear Jitter & Instability Trajectory Recovery
Restoring Blurred Space Telescope Images from Spacecraft Jitter
Unguided Spacecraft Drift vs. Restored Airy Core
During fast target-of-opportunity pointings, the Swift space telescope drifts without a guide-star lock. Reaction-wheel jitter smears stars into long streaks across the detector. UNJITR tracks this motion directly from photon arrival times, turning smeared ribbons back into sharp, focused point sources.
Performance Across 4 Physical Jitter Regimes
Spacecraft jitter ranges from subtle pointing drift to rapid 15-second wobble and wide wandering paths. Explore how UNJITR restores image sharpness across each motion type.
The 4 Spacecraft Jitter Regimes
The 4-Step UNJITR Restoration Engine
Instead of relying on star catalogs or noisy sensor telemetry, UNJITR reconstructs telescope drift directly from the arrival times of individual photons.
Direct-Photon Cross-Correlation Pipeline
Complete Mathematical Architecture Flowchart
Eliminating Orbit-Long Star Doubling Across Sub-Exposures
When an orbit observation is split into multiple exposures, slight pointing shifts between them create duplicate 'ghost' stars when stacked. UNJITR aligns all exposures to a single master frame, merging split stars back into single sharp points.
The Star Doubling Problem
Standard pipeline tools stack sub-intervals without sub-pixel inter-frame registration. Small attitude slews between intervals cause every star in the field to appear as a false binary system, destroying scientific astrometry.
Master Anchor Registration
UNJITR automatically designates the highest-count interval as master anchor H₀. Secondary intervals are cross-correlated against H₀ in the Fourier domain, establishing a rigid global astrometric datum across the entire 45-minute orbit.
Diffraction-Limited Stacking
All photon events across all GTIs are transformed into the master coordinate system prior to stacking. Stellar FWHM collapses from > 6.2″ split doubles into a single symmetric 3.1″ core, perfectly preserving total flux.
Stellar PSF Stamps: Before vs. After Across Multiple GTIs
High-resolution star stamps from isolated calibration stars located > 1,200 detector pixels from the galaxy nucleus. Serpentine filaments, diagonal slews, and dumbbell elongations are consistently collapsed into circular diffraction cores with sharp Gaussian profiles.
282-Observation Archival Campaign Benchmark
To demonstrate production readiness and archive-scale robustness, UNJITR was executed across the entire Swift UVOT archival observation campaign of the dwarf Seyfert galaxy NGC 4395, comprising 329 Good Time Intervals across 282 separate pointing datasets.
| QA Classification | Count | Percentage | Physical Criteria |
|---|---|---|---|
| ACCEPTED | 314 | 95.4% | PSF EER ≥ +5% & cross-corr peak ≥ 0.45 |
| MARGINAL | 14 | 4.3% | Low photon count; partial recovery; passed null test |
| REJECTED | 1 | 0.3% | > 1,100 px catastrophic roll & field-rotation limit |
| RECOVERY RATE | 328 / 329 | 99.7% | Non-Rejection Operational Success |
Strict Do-No-Harm FITS Contract
Scientific integrity is paramount. Astronomical archives cannot tolerate altered telemetry. UNJITR enforces a strict cryptographic byte-contract ensuring zero irreversible corruption:
Pipeline Architecture & Release Status
The UNJITR software package is being prepared for public release alongside peer-reviewed methodology and software papers.
Code repository is currently private pending publication of companion papers.
Hoisted 2D FFT cross-correlation, sub-pixel vertex fitting, and automated Do-No-Harm quality gates.
Methodology and software architecture papers currently in final author review.
Scientific Literature & Citation Manifest
Methods, astrophysical validation, and software architecture submitted for peer review. Use the buttons below to copy formatted BibTeX entries.
Blind Sub-Pixel Photon-Event Jitter Restoration and Astrometric Alignment for Space Observatories: UNJITR Algorithm, Spacecraft Dynamics, and Swift UVOT Archive Recovery
Formulates the UNJITR (UV/Optical Nonlinear Jitter & Instability Trajectory Recovery) framework: direct photon-stream attitude drift reconstruction at 6.7 Hz, the 1.0s correlation slab discovery, and master orbit coregistration. Achieves a 99.7% archive recovery rate across 282 Swift UVOT galaxy observations under extreme reaction-wheel limit cycling.
UNJITR: A Python Toolkit for Sub-Pixel Photon-Event Jitter Correction and Astrometric Sharpening
Details the forthcoming UNJITR Python package, implementing hoisted 2D Fast Fourier correlation, sub-pixel parabolic vertex fitting, automated Do-No-Harm quality gates, and high-throughput batch FITS event processing. Software release in preparation alongside peer-reviewed publication.