arXiv subjects

Nico Pfeffer

Publications and source records attributed to Nico Pfeffer.

2 recordsLinked to original sources

arXiv2026

The PANSY Meteor Head-echo Orbit Catalogue: Continuous Antarctic Radar Observations of Southern Meteoroid Streams

Meteor head echoes from high-power, large-aperture radars provide pulse-resolved positions and velocities for individual micrometeoroids in a submillimeter-radius range that contribute significantly to the mass influx to Earth. We present the first meteor head-echo orbit catalogue from the Antarctic Syowa Mesosphere--Stratosphere--Troposphere/Incoherent Scatter radar (PANSY). The catalogue contains two million meteors and 50 million pulse-resolved measurements. The observed radiant distribution contains the helion, antihelion, south toroidal and apex sources, and provides unprecedented head-echo coverage of southern ecliptic latitudes. The initial detection-height distribution is found to be double-banded, with both bands increasing in height with meteor speed and exhibiting distinct radiant distributions, consistent with a mixture of meteoroid-size differences and differential ablation. Estimation of dynamic mass indicates that the survey is sensitive to initial radii of approximately 100 micrometers. As part of an initial exploration of the catalogue, we investigate the nighttime alpha Capricornids (CAP) and the extended Daytime Capricornids-Sagittariids (DCS) radiant. Their similar activity durations at opposite nodes are consistent with membership in the CAP--169P/NEAT complex. The radiant distribution suggests a new meteor shower candidate, with peak flux near solar longitude 110 degrees, mean Sun-centered ecliptic radiant longitude 291.0 degrees, latitude -48.2 degrees, and geocentric speed 48.7 km s^{-1}. During catalogue production, event-level raw voltage cuts are retained temporarily to support improvements in data analysis. This first catalogue release, covering 2025 January 26 to 2026 July 26, will be useful for further studies of the southern-hemisphere Earth-crossing meteoroid population.

astro-ph.EP↗

arXiv2026

Optical and Radar Observations of the February 2025 Falcon 9 Upper-Stage Re-entry

We investigate the February 19, 2025, re-entry of a Falcon 9 upper stage using optical observations from 43 meteor cameras across central Europe together with radar detections of re-entry plasma obtained with the 32.55 MHz SIMONe Germany multistatic radar system. Optical observations of fragment emissions between 85 and 36 km altitude were used to reconstruct 30 fragment trajectories, identify two main fragment families, and fit ballistic trajectories to estimate kinetic energy loss per unit mass. The optical detection-height distribution peaks near 60 km with a standard deviation of 10 km, and both optical and radar signatures occur in the same broad altitude region as the maximum kinetic-energy loss. Radar echoes were detected at altitudes between 55 and 75 km, and the radar-derived positions are consistent with those obtained from optical observations. Two distinct radar echo types associated with the re-entry plasma were identified: (1) specular trail echoes from overdense wake plasma, with radar cross-sections (RCS) of up to 60 dBsm, and (2) short-lived non-specular trail echoes with RCS values of 20--30 dBsm, exhibiting a delay of 1--2 s compared to optical signatures. The characteristic decay time of both echo types is approximately 1 s. In the radar-echo altitude range, the estimated Knudsen numbers for meter-scale fragments are well below unity, consistent with continuum-flow conditions and shock-driven plasma production rather than ordinary meteor-like impact ionization. These serendipitous radar observations demonstrate that the atmospheric re-entry of other spacecraft, including objects smaller than the Falcon 9 upper stage such as Starlink satellites, may likewise be detectable using comparable multistatic meteor radar systems deployed globally.

physics.space-ph↗