Intracalibration of particle detectors on a three‐axis stabilized geostationary platform

Abstract

We describe an algorithm for intracalibration of measurements from plasma or energetic particle detectors on a three‐axis stabilized platform. Modeling and forecasting of Earth's radiation belt environment requires data from particle instruments, and these data depend on measurements which have an inherent calibration uncertainty. Pre‐launch calibration is typically performed, but on‐orbit changes in the instrument often necessitate adjustment of calibration parameters to mitigate the effect of these changes on the measurements. On‐orbit calibration practices for particle detectors aboard spin‐stabilized spacecraft are well established. Three‐axis stabilized platforms, however, pose unique challenges even when comparisons are being performed between multiple telescopes measuring the same energy ranges aboard the same satellite. This algorithm identifies time intervals when different telescopes are measuring particles with the same pitch angles. These measurements are used to compute scale factors which can be multiplied by the pre‐launch geometric factor to correct any changes. The approach is first tested using measurements from GOES‐13 MAGED particle detectors over a 5‐month time period in 2010. We find statistically significant variations which are generally on the order of 5% or less. These results do not appear to be dependent on Poisson statistics nor upon whether a dead time correction was performed. When applied to data from a 5‐month interval in 2011, one telescope shows a 10% shift from the 2010 scale factors. This technique has potential for operational use to help maintain relative calibration between multiple telescopes aboard a single satellite. It should also be extensible to inter‐calibration between multiple satellites.

Intercalibration of GOES 8–15 solar proton detectors

“…The standard errors of A 0 and A 1 are calculated from these 50 results. If there are fewer than 30 points in the comparison, no analysis is performed [Rowland and Weigel, 2012].…”

On-orbit calibration of geostationary electron and proton flux observations for augmentation of an existing empirical radiation model

“…The vertical (northsouth) fan is composed of five telescope FOVs with center angles at 0°, ±35°and ±70°from the equatorial plane, the 0°telescope (Telescope 1) looking radially outward in the equatorial plane (toward zenith). The horizontal (east-west) fan is composed of four additional telescope FOVs with center angles at ±35°and ±70°from the north to south plane, as illustrated elsewhere (Rowland & Weigel, 2012;Sillanpää et al, 2017). The MAGED and MAGPD channel names and energies are listed in Table 1.…”

“…However, despite the disturbed conditions, telescope 9 has only one such pitch-angle match with another telescope during this period. Such cases, in which two telescopes observe fluxes at the same local pitch angle, form the basis for the telescope intra-calibration technique of Rowland & Weigel (2012), applied in Section 4.2 to the MAGED and MAGPD data.…”

The STONE curve: A ROC-derived model performance assessment tool

“…This resulted in a nonmonotonic wiggle in the STONE curve at these thresholds. Ganushkina et al (2019) compared real-time output from the inner magnetosphere particle transport and acceleration model (IMPTAM) with measurements from the magnetosphere electron detector (MAGED) on the geosynchronus orbiting environmental satellites (GOES) in geostationary orbit at 6.62 Earth radii geocentric distance over the American sector (Rowland & Weigel, 2012;Sillanpaa et al, 2017), specifically, with data from GOES-13, -14, and -15. IMPTAM, initially developed by Ganushkina et al (2001) and used regularly for investigating the physics of plasma sheet electron transport (e.g., Ganushkina et al, 2013Ganushkina et al, , 2014, has been running in a real-time operational mode since February 2013, first in Europe and then a mirror site at the University of Michigan.…”