Astronomy and Geodesy (AstroGeo)

Geodesy uses astronomical techniques to measure the Earth’s shape, gravitational field, and position in space. This helps scientists better understand processes such as plate tectonics, ocean tides, the atmosphere, and the motion of the Earth’s poles.

The following resources provide products to assist researchers in the field of geodesy, astronomy, and geophysics.

The AstroGeo Data Point of Contact is Leonid Petrov.

Astronomy and Geodesy Scientific Data Products

This collection of Astronomy and Geodesy Scientific Data Products includes catalogs of compact radio source positions and their their images, the atmospheric angular momentum online service, and links to the space geodesy services that are also listed below.

International Path Delay Service

The International Path Delay Service uses the output of assimilation numerical weather models to compute slant path and zenith path delays in the atmosphere at radio, infrared, or optical ranges, including dry and wet components. In addition, it computes atmospheric opacity and atmosphere brightness temperature in a range of 1 to 360 GHz.

The service solves the logistical problems of downloading large datasets, preprocessing large datasets, and performing CPU-intensive computations at a dedicated server. It also presents the results in a form that can be used for analyzing data from Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), Very Long Baseline Interferometry (VLBI), radioastronomy, Interferometric Synthetic Aperture Radar (InSAR), and airborne and spaceborne altimetry. The service provides access to data products that can either be used directly or via client software.

International Mass Loading Service

The Earth as a whole responds to external forces as an elastic body. Putting an additional mass on the Earth’s surface causes crust deformation. Changes in mass loading create variable displacements of the Earth’s surface. If not properly accounted for, such variations distort precise geodetic measurements.

The goal of the International Mass Loading Service is to ingest the outputs of numerical models, compute 3D displacements caused by mass loading, and regularly disseminate the results for the entire geodetic community with low latencies. The service is provided free of charge, and no registration is required.

Network Earth Rotation Service

Earth orientation parameters (EOP) describe irregularities in the Earth’s rotation compared to a fixed frame of reference. They are determined partly from observations and partly from numerical weather models. The Network Earth Rotation Service (NERS) is an online tool that provides automatic access to EOP from 1976.01.01 through 48 hours in the future.

Since the irregularities in Earth’s rotation are caused by the motions of the hydrosphere and atmosphere, no deterministic model can describe them as accurately as observations can. Earth’s rotation is constantly monitored by space geodesy observations. The NERS assembles the results of data analysis from Very Long Baseline Interferometry (VLBI), Global Navigation Satellite Systems (GNSS), and the output of numerical models, computes the short-term EOP forecast, takes the long-term EOP forecast distributed by the Paris Observatory, and presents the results in a form convenient for users.