Preprint catalogs 263 GNSS occultation arcs observed in cislunar space and on the Moon

Findings

Researchers compiled an observational dataset of 263 dispersive arcs attributed to ionospheric and plasmaspheric occultation. The arcs appeared in Global Navigation Satellite System signals recorded by the Lunar GNSS Receiver Experiment, or LuGRE, during Blue Ghost Mission 1. The receiver collected the signals while in cislunar space and on the lunar surface.

The researchers identified and classified the arcs as ingress, egress or tangent events. Their approach combined independently obtained dual-frequency observations from GPS and Galileo, calculations of the rate of total electron content and its variability index, and a geometric validation criterion based on the grazing altitude of the signal’s tangent point.

For each arc, the catalog supplies its timing and grazing altitude, the level of geomagnetic activity, and summary measurements related to electron content. It also includes time series for leveled slant total electron content, its rate and variability, and the tangent point’s position and local time. The HDF5 file contains dataset-wide metadata, statistics for the event classes and one entry for each arc.

Why it matters

According to the researchers, the catalog allows users to select occultation arcs quickly for statistical studies or targeted analyses. They say observations made from cislunar and lunar-surface locations can complement radio-occultation data collected from the ground and from low Earth orbit during the declining phase of solar cycle 25. The abstract reports the creation of a research resource; it does not present findings from those future analyses.

What remains uncertain

The catalog does not separate the ionospheric and plasmaspheric contributions to an arc. Instead, each event is represented as a single combined dispersive signature. The slant total electron-content time series have also not been corrected for instrumental biases.

The abstract does not provide uncertainty estimates, detection accuracy, the number of events in each class, or comparison against an independent reference dataset. It also does not state how many potential arcs were missed. Completeness, representativeness and measurement error therefore cannot be assessed from the available abstract. The work is an arXiv preprint and has not been peer reviewed.