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The redshifted $21$\,cm signal of neutral hydrogen can be used as a direct probe of the intergalactic medium during Cosmic Dawn\,(CD) and Epoch of Reionization\,(EoR). However, detecting this inherently weak signal has numerous challenges.…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-28 Samit Kumar Pal , Abhirup Datta , Aishrila Mazumder

Most data-driven ionospheric forecasting models operate on gridded products, which do not preserve the time-varying sampling structure of satellite-based sensing. We instead model the ionosphere as a dynamic graph over ionospheric pierce…

Machine Learning · Computer Science 2026-04-21 Mert Can Turkmen , Eng Leong Tan , Yee Hui Lee

In radio astronomy, the correlator measures intensity in visibility space. In addition, the EoR power spectrum measured by an experiment such as the MWA is constructed in visibility space. Thus, correcting for the ionosphere in the uv-plane…

Instrumentation and Methods for Astrophysics · Physics 2009-11-23 Michael S. Matejek , Miguel F. Morales

The stability of GPS time and frequency transfer is limited by the fact that GPS signals travel through the ionosphere. In high precision geodetic time transfer (i.e. based on precise modeling of code and carrier phase GPS data), the…

We have investigated a dependence of the relative density of phase slips in the GPS navigation system on the disturbance level of the Earth's magnetosphere. The study is based on using Internet-available selected data from the global GPS…

Geophysics · Physics 2007-05-23 E. L. Afraimovich , O. S. Lesyuta , I. I. Ushakov

Results derived from analysing the ionosphere response to faint and bright solar flares are presented. The analysis used technology of a global detection of ionospheric effects from solar flares as developed by the authors, on the basis of…

Geophysics · Physics 2007-05-23 L. A. Leonovich , A. T. Altynsev , E. L. Afraimovich , V. V. Grechnev.

Context: Low-frequency radio observations are heavily impacted by the ionosphere, where dispersive delays can outpace even instrumental clock offsets, posing a serious calibration challenge. Especially below 100 MHz, phase unwrapping…

Instrumentation and Methods for Astrophysics · Physics 2025-10-03 C. M. Cordun , M. A. Brentjens , H. K. Vedantham , M. Mevius

The gravimetry measurements from the Gravity Recovery and Climate Experiment (GRACE) and its follow-on (GRACE-FO) satellite mission provide an essential way to monitor changes in ocean bottom pressure ($p_b$), which is a critical variable…

Geophysics · Physics 2025-02-20 Junyang Gou , Lara Börger , Michael Schindelegger , Benedikt Soja

The GRACE mission has been providing valuable new information on time variations in the Earth's gravity field since 2002. In addition, the GRACE Follow-On mission is scheduled to be flown soon after the end of life of the GRACE mission in…

Space Physics · Physics 2015-06-18 Peter L. Bender , Casey R. Betts

Dose-Response Functions (DRFs) are widely used in estimating corrosion and/or soiling levels of materials used in constructions and cultural monuments. These functions quantify the effects of air pollution and environmental parameters on…

In the effort to obtain low cost routine space debris observations in low Earth orbit, ESA plans to utilise the radar facilities of the European Incoherent Scatter Scientific Association. First demonstration measurements were performed from…

Astrophysics · Physics 2009-11-07 M. Landgraf , R. Jehn , W. Flury

We present new data processing techniques that allow to correct the main instrumental effects that degrade the images obtained by ISOCAM, the camera on board the Infrared Space Observatory (ISO). Our techniques take advantage of the fact…

Astrophysics · Physics 2009-10-31 M. -A. Miville-Deschenes , F. Boulanger , A. Abergel , J. -P. Bernard

Up to now attempts to measure the general relativistic Lense-Thirring effect in the gravitational field of Earth have been performed by analyzing a suitable J_2-J_4-free combination of the nodes Omega of LAGEOS and LAGEOS II and the perigee…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Lorenzo Iorio

This paper presents data from first GPS measurements of global response of the ionosphere to solar flares of September 23, 1998 and July 29, 1999. The analysis used novel technology of a global detection of ionospheric effects from solar…

We describe a Simplified Gravitational Reference Sensor (S-GRS), an ultra-precise inertial sensor for future Earth geodesy missions. These sensors are used to measure or compensate for all non-gravitational accelerations of the host…

This paper presents a case study from a single, six-hour observing period to illustrate the application of techniques developed for interferometric radio telescopes to the spectral analysis of observations of ionospheric fluctuations with…

Space Physics · Physics 2014-02-05 Joseph Helmboldt , Huib Intema

High resolution (~1 arcminute) astronomical imaging at low frequency (below 150 MHz) has only recently become practical with the development of new calibration algorithms for removing ionospheric distortions. In addition to opening a new…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 A. S. Cohen , H. J. A. Röttgering

The ambitious scientific goals of SKA require a matching capability for calibration of instrumental and atmospheric propagation contributions as functions of time, frequency and position. The development of novel calibration algorithms to…

Instrumentation and Methods for Astrophysics · Physics 2022-02-01 María J. Rioja , Richard Dodson

This paper proposes a new method for estimating the contribution from different ionospheric regions to the response of total electron content variations to the solar flare which uses the effect of partial shadowing of the atmosphere by the…

Geophysics · Physics 2015-06-26 L. A. Leonovich , E. L. Afraimovich , E. B. Romanova , A. V. Taschilin

The gravity field maps of the satellite gravimetry missions GRACE (Gravity Recovery and Climate Experiment) and GRACE Follow-On are derived by means of precise orbit determination. The key observation is the biased inter-satellite range,…

Instrumentation and Methods for Astrophysics · Physics 2021-04-12 Yihao Yan , Vitali Müller , Gerhard Heinzel , Min Zhong