2019 SLR Etalon-1 and -2 tracking campaign


SLR has the opportunity to play a more significant role on the determination of Earth Orientation Parameters (EOP), an important element in the reference frame and parameters for many of our customers. The ILRS ASC proposed conducting a 3-month Etalon tracking campaign in 2019. Although we have tried in the past to strengthen our role, the SLR data has been too sparse. Now, however, with our improving ability to track GNSS satellites, it is incumbent upon us to try again. We would need to at least double the number of passes and increase the pass coverage on the two Etalon satellites. The next 3 months is a good time to try; the passes of LAGEOS and LAGEOS are well separated and most of the very productive stations will have some Etalon pass time in darkness.

Therefore, we are conducting a 3-month Etalon campaign, from February 15 through May 15, 2019.

Ideally, we would like the Etalon orbit sampled with 3 NPs at low elevation early in the pass, 3 NPs around maximum elevation, and 3 NPs toward the end of the pass. Choose long passes if available. We would like each station to try to get one pass on each of the Etalon satellites, each day, if conditions allow it. If you cannot get 3 segments in the pass, try for 2. If you cannot get 2, try for one. Every bit of enhanced data will help.

Weekly reports on station tracking during the campaign are available:

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.