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Overview

Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) use short-pulse lasers and state-of-the-art optical receivers and timing electronics to measure the two-way time of flight (and hence distance) from ground stations to retroreflector arrays on Earth orbiting satellites and the Moon. Scientific products derived using SLR and LLR data include precise geocentric positions and motions of ground stations, satellite orbits, components of Earth’s gravity field and their temporal variations, Earth Orientation Parameters (EOP), precise lunar ephemerides and information about the internal structure of the Moon. Laser ranging systems are already measuring the one-way distance to remote optical receivers in space and can perform very accurate time transfer between sites far apart. Laser ranging activities are organized under the International Laser Ranging Service (ILRS) which provides global satellite and lunar laser ranging data and their derived data products to support research in geodesy, geophysics, Lunar science, and fundamental constants. This includes data products that are fundamental to the International Terrestrial Reference Frame (ITRF), which is established and maintained by the International Earth Rotation and Reference Systems Service (IERS). The ILRS develops the necessary global standards/specifications for laser ranging activities and encourages international adherence to its conventions.

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Highlights

2019 ILRS Technical WorkshopRelease Date: 08/06/2019The 2019 ILRS Technical Workshop will take place in Stuttgart, Germany, October 21-25. If you plan to attend, please register by August 15 (next Thursday) on the workshop website:

https://ilrsworkshop2019.besl-eventservice.de/front/index.php

If you have any trouble registering, please send an email to ilrs.workshop@dlr.de.

If you plan to present at the workshop, we ask that you also upload your abstract as soon as possible so we can commence planning the program.

The ILRS is looking forward to seeing you all in Stuttgart!

GNSS Tracking StrategyRelease Date: 08/01/2019 The ILRS has been working with the IGS and other interested parties to settle on a GNSS tracking strategy that would satisfy both mission and user requirements. For some applications, users want denser tracking on a few satellites. For other applications, users want some tracking on the full complex of GNSS satellites, even if that tracking is sparse. In addition, there are also requests for focused campaigns, in particular, for tracking GNSS satellites while going through Earth shadow to study the effects of radiation pressure. We presently have over 60 GNSS satellites (GLONASS, Galileo, BeiDou) on the ILRS roster. More will be added in the near future. The total could reach nearly 100 when GPS is added in the 2024 timeframe.

The strategy that the ILRS has agreed to implement is the following:

GNSS tracking will continue to be prioritized with the other ILRS satellites by the standard ILRS priority scheme (by altitude and inclination);
Four GNSS satellites will be identified by each constellation (Galileo, GLONASS, and BeiDou) for intensive tracking, with three sectors (at least 2 normal points each) spaced widely apart over the pass. If stations cannot obtain three sectors they should try to get two sectors. These four satellites per constellation would be selected by the constellation and would have the highest priority among the GNSS satellites.
All of the remaining GNSS satellites would be tracked by the stations on an as time available basis; selection of targets should be determined by the stations for data yield, but stations are asked to try to diversify among all three constellations because we need some data on all three.
There may be some special tracking periods (e.g. satellite eclipses, etc.) that may need other scheduling.

The agreed high priority GNSS satellites are:

BeiDou3-M2, 3-M3, 3-M9, and 3-M10
Galileo-102, -202, -209, -210
GLONASS-131, -134, -138, and -139

The ILRS asks that you implement this new priority strategy in your tracking operation, by August 15, 2019. Please contact the ILRS CB if you have any questions.

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Recent News

GNSS Tracking Strategy - The ILRS has been working with the IGS and other interested parties to settle on a GNSS tracking strategy that would satisfy both mission and user requirements. For some applications, users want denser tracking on a few satellites. For other applications, users want some tracking on the full complex of GNSS satellites, even if that tracking is sparse. In addition, there are also requests for focused campaigns, in particular, for tracking GNSS satellites while going through Earth shadow to study the effects of radiation pressure. We presently have over 60 GNSS satellites (GLONASS, Galileo, BeiDou) on the ILRS roster. More will be added in the near future. The total could reach nearly 100 when GPS is added in the 2024 timeframe.

Read more...

2019 ILRS Technical Workshop - The 2019 ILRS Technical Workshop will take place in Stuttgart, Germany, October 21-25. If you plan to attend, please register by August 15 (next Thursday) on the workshop website:

https://ilrsworkshop2019.besl-eventservice.de/front/index.php

If you have any trouble registering, please send an email to ilrs.workshop@dlr.de. If you plan to present at the workshop, the ILRS asks that you also upload your abstract as soon as possible so we can commence planning the program. We are looking forward to seeing you all in Stuttgart!

Results of the 2019 Etalon-1 and -2 tracking campaign released - The results from the actual data analysis of the Etalon campaign period, focusing on the EOP improvement have been collected. Data from the same timeframe in 2018 were reanalyzed in order to have results compared to exactly the same IERS C04 series. As can be seen in this report, the additional Etalon data makes a significant difference, bringing the ILRS EOP product a lot closer to the "final" IERS series (which is ∼90% a GNSS product). The ILRS Analysis Coordinators have requested that the network do their best to increase their collection of Etalon data on a permanent basis.

Updated data screening process at the ILRS Operations Centers (OCs) at EDC and NASA - The ILRS Operations Centers (OCs) at EDC and NASA are updating their data screening process in order to coordinate data quality control (QC) and provide feedback on data issues to the stations. Incoming data will be screened and characterized as:

"errors" if they will adversely impact the quality of the data and the derived data products (e.g., invalid date, invalid satellite, erroneous calibration, etc.)
"warnings" if the impact on the quality of the data is minor, or if there are format errors that make processing or QC evaluation more difficult.

Data that are marked as having errors will not be submitted to the ILRS Data Centers at EDC and CDDIS. Data marked as having warnings will be submitted.

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