Philip J. Castro, Applied Optimization, Inc.; Tamara E. Payne, Applied Optimization Inc.; Luke W. Weisenbach, Applied Optimization Inc; Trenton J. Godar, U.S. Government; Veronica L. Wiley, U.S. Government; James Frith, AFRL/RVSW; Scott P. Milster, AFRL/RVSW
Keywords: photometry, non-resolved object characterization, spectral, color index, Space Situational Awareness (SSA), Space Domain Awareness (SDA)
Abstract:
We present an analysis of induced color index error due to sequential filter photometry. We performed an analysis on multi-filter photometry signatures of three-axis stabilized GEOs to estimate the color index error due to forming color indices using sequential filter photometry. A color index is the difference in magnitude between two filters. Its formation assumes that the objects brightness is not changing during the collection of the two magnitudes.
For this analysis, we will utilize four-filter photometric signatures collected simultaneously. We performed glint season observations of GEOs using our system called Peacock with the goal of collecting simultaneous filter photometry that contains signatures that are rapidly changing. Peacock is a persistent, wide-field-of-view, simultaneous multispectral system built and operated by Applied Optimization.
The color indices formed from sequential filter photometry may contain non-negligible error when the object brightness is rapidly changing with respect to the filter duty cycle. We refer to this error as induced color index error. Characterization of RSOs using color indices could be affected by the induced color index error during these dynamic brightness periods. We converted the simultaneous signatures to form sequential signatures for our analysis. By forming color indices with the simultaneous data, which we define as truth, and taking the difference between color indices formed using the sequential data, we calculate the induced color index error. We found that the dynamic brightness regions of a 3-axis stabilized GEO signature due to solar panel glints and body glints contain induced color index error of up to about 30%. The Space Domain Awareness (SDA) community should be cognizant of the potential existence of this error when using color indices formed from sequential filter photometry for characterization, as this error is intrinsic and could not be reported by the SDA data providers.
This abstract was approved for public release. Case number: AFRL-2022-1559.
Date of Conference: September 27-20, 2022
Track: Non-Resolved Object Characterization