LAGEOS-1, -2: Array Offset Information
Center of Mass Information:
Previously, Center-of-Mass (CoM) values used for LAGEOS-1 and LAGEOS-2 relied on the work of Otsubo and Appleby (J. Geophys Res., 2003). These values have been superceded by the new work described by Rodríguez et al. (J. Geodesy, 2019). The new values can result in a ∼4.5 mm for the LAGEOS satellites compared to earlier modelling. A more detailed description of the updated modelling is provided below.José Rodríguez (IGN, Spain) in collaboration with Graham Appleby (BGS, UK) and Toshimichi Otsubo (Hitotsubashi University, Tokyo, Japan) has modelled the most relevant effects to compute tables of CoM corrections for the geodetic satellites including LAGEOS-1 and LAGEOS-2. The corrections attempt to account to the best extent possible for the relevant documented change in configurations at the laser ranging stations of the ILRS. The latest models are available from a data server at IGN Spain (see below). The tar files contain the data tables, and example software to read this information to return the desired CoM value for a particular satellite on a certain date. Users should read carefully the ILRS Data Handling File (DHF) and use the CoM model specified in the Data Handling File. This is because the applied biases for ILRS stations in the DHF are tied to the CoM model that is used.
When using these CoM models in analysis of SLR data, the following citation should be used:
Rodríguez J., Appleby G. & Otsubo, T. (2019). “Upgraded modelling for the determination of centre of mass corrections of geodetic SLR satellites: impact on key parameters of the terrestrial reference frame”, J. Geodesy, 93, 2553–2568, doi:10.1007/s00190-019-01315-0.
A summary of recent updates is also available in a technical report prepared by José Rodríguez:
Rodríguez J C. (2022). “Centre of mass corrections updates for geodetic spherical satellites: Changes in the latest releases in preparation for the computation of ITRF2020 products”, Technical Report IT-CDT 2022-11, Yebes Observatory, Spain, Nov. 22, 2022.
Link to download the latest CoM models for the geodetic satellites (including LAGEOS-1 & LAGEOS-2), as well as documentation materials:
URL: https://datos-geodesia.ign.es/SLR/centre_of_mass_models/
Other references:
- Arnold, David A. (1978). “Optical and Infrared Transfer Function of the LAGEOS Retroreflector Array”, Smithsonian Institution Astrophysical Observatory, Cambridge, Massachusetts, May 1978
- Arnold, David A. (1979). “Method of Calculating Retroreflector-Array Transfer Functions”, Smithsonian Astrophysical Observatory, Cambridge, Massachusetts, February, 1979
- Fitzmaurice M.W., P.O. Minott, J.B. Abshire, and H.E. Rowe (1974), “Prelaunch testing of the laser geodynamic satellite (LAGEOS)”, NASA Tech. Pap., TP-1062, 1974
- Minott, P.O., T.W. Zagwodzki, T. Varghese, and M. Selden (1993). “Prelaunch optical characterization of the Laser Geodynamic Satellite (LAGEOS 2)”, NASA Tech. Paper, TP-3400, 1993
