SGRs denote “soft γ-ray repeaters”, a small class of slowly spinning neutron stars with strong magnetic fields. On 27 December 2004, a giant flare was detected from magnetar SGR 180620. The initial spike was followed by a hard-X-ray tail persisting for 380 s with a modulation period of 7.56 s. This event has received considerable attention, particularly in the astrophysics area. Its relevance t...

In this paper we calculate explicitly the secular classical precessions of the node Ω and the perigee ω of an Earth artificial satellite induced by the static, even zonal harmonics of the geopotential up to degree l = 20. Subsequently, their systematic errors induced by the mismodelling in the even zonal geopotential coefficients Jl are compared to the general relativistic secular gravitomagnet...

There is a need to develop secular variation (SV) models using satellite data as the use of ground data is not always possible. Ground data has many limitations including limited data points and lack of data over ocean areas that are not easily accessible. Two regional geomagnetic field modelling techniques, namely polynomial surface modelling (PolyM) and Spherical Cap Harmonic Analysis (SCHA),...

The gravity field dedicated satellite missions like CHAMP, GRACE, and GOCE are supposed to map the Earth’s global gravity field with unprecedented accuracy and resolution. New models of Earth’s static and time-variable gravity field will be available every month as one of the science products from GRACE. Here we present an alternative method to estimate the gravity field efficiently using the i...

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The Multi-Instrument Data Analysis System (MIDAS) algorithm is a spatial and temporal imaging program for the atmosphere and ionosphere. This analysis algorithm can routinely use dual-frequency ground-based observations from the GPS satellites to produce four-dimensional images of electron concentration over very large geographical regions (potentially globally). MIDAS also has the facility to ...

Precision orbit ephemerides (POE) are used to estimate atmospheric density along the orbits of CHAMP (Challenging Minisatellite Payload) and GRACE (Gravity Recovery and Climate Experiment). The densities are calibrated against accelerometer derived densities and considering ballistic coefficient estimation results. The 14-hour density solutions are stitched together using a linear weighted blen...

Bursts of very intense kilometer-scale fieldaligned currents (KSFACs) are observed quite frequently by the CHAMP satellite when passing through the auroral region. In extreme cases estimated current densities exceed 3 mA/m2. Typical scale sizes of these KSFACs are 1 km. The low-Earth, polar orbiting satellite CHAMP allows one to assess KSFACs down to scales of a couple of 100 m based on its hig...

In this thesis, an integrated approach is developed for the regional renement of global gravity eld solutions. The analysis concepts are tailored to the in-situ type character of the observations provided by the new satellite missions CHAMP, GRACE, and GOCE. They are able to evaluate data derived from short arcs of the satellite's orbit and, therefore, oer the opportunity to use regional satell...

This study examined the convergent construct validity of a new performance-based assessment instrument called the Comprehensive High-Level Activity Mobility Predictor (CHAMP) as a measure of high-level mobility in servicemembers (SMs) with traumatic lower-limb loss (LLL). The study was completed by 118 SMs. Convergent construct validity of the CHAMP was established using the 6-minute walk test ...