Phineas Whitlock, University of Warwick; James McCormac, University of Warwick; Paul Chote, University of Warwick
https://doi.org/10.64861/YVXR9470
Keywords: Parallax, Optical Tracking, Multi-Site Observation, Astrometry, Photometry, SSA, SDA
Abstract:
With recent rapid growth of the space sector, accurate tracking of Resident Space Objects (RSOs) is becoming more crucial for maintaining the continued use of space. In space asset management, high-precision orbital data is required for collision avoidance, manoeuvre scheduling and launch planning. Public orbital data is largely limited to Two-Line Elements (TLEs), mean orbital elements that lack precision and propagation accuracy, whereas commercial high-fidelity ephemerides often come at a high cost. As the ease of access to space increases, the development of accurate, cost-effective tracking techniques must also rise to meet the increased congestion.
We present a dual-telescope optical system that uses parallax to derive 3D coordinates of RSOs. Both instruments pair a 14” Celestron Rowe-Ackermann Schmidt Astrograph (RASA) with a QHY600M CMOS sensor on Planewave direct-drive mounts. This system achieves a 2.63×1.76 degree field of view at 2.97”/pixel with 3×3 binning to decrease data rate. Warwick’s CLASP is the primary instrument, permanently installed at the Roque de los Muchachos Observatory, La Palma. The secondary instrument, built from Commercial Off-The-Shelf (COTS) components costing less than £50,000, is used for flexible multi-baseline testing. The pair observe the same known RSO with the goal of acquiring high-precision ephemeris data.
Two observation campaigns characterised and validated system performance. An initial short-baseline campaign in August 2024 (2 km and 1.6 km baselines in La Palma) tested concept feasibility and components. A follow-up campaign in August 2025 extended the baseline test between CLASP on La Palma and the portable system on Tenerife (140 km) and El Hierro (110 km). An automated observation strategy was developed to target a diverse catalogue of RSOs for evaluating system performance. Object variety was enforced to test the applicability of the technique for differing orbital altitudes/regimes, and object types, sizes and attitudes. Across both campaigns, over 250 unique objects were observed with a total of 1100 orbital arcs.
Image processing diverges from traditional astronomical techniques due to the highly streaked star morphology in tracked images. Our processing acquires sub-pixel astrometric accuracy for all orbital regimes and is highly optimised for a daily turnaround of acquired data. Extracted on-sky coordinates of the RSO are synchronised and interpolated. From these, the parallax angle is derived from the closest approach between the line-of-sight (LOS) vectors. For the small baseline test, accuracy was poor, with range errors of 10 km at LEO and over 1,000 km at GEO. Initial results from the extended baseline test show range improvements of over two orders of magnitude, achieving sub-100 m at LEO and sub-10 km at GEO. The LOS range and angle give access to 3D positional coordinates, which can be used for orbital determination and refinement.
For both systems, photometry is performed to calculate a zero point and extract the magnitude of target RSOs over the observed arc. These light curves can be used to analyse RSO operational status, physical characteristics, and attitude dynamics, such as extracting spin-rates of rocket bodies to aid in end-of-life assessment or active debris removal.
This work demonstrates the viability of low-cost COTS optical assemblies employing parallax to generate 3D positional measurements. By providing capabilities for both ephemeris generation and photometric characterisation, this two-site optical system provides a scalable, cost-effective solution to the current challenges of the congested space environment.
Date of Conference: September 15-18, 2026
Track: SDA Systems & Instrumentation