The SLR contribution to ITRF is nowadays a time series of weekly
station coordinates and daily Earth Orientation Parameters (X-pole,
Y-pole and excess Length-Of-Day (LOD)) estimated over 7-day arcs
(15-day arcs for the period 1983-1992) aligned with calendar weeks
(Sunday to Saturday), starting from January 1983. Each weekly
solution is obtained through the combination of weekly solutions
submitted by the official ILRS Analysis Centers (ASI, BKG, DGFI,
ESA, GA, GFZ, GRGS, JCET and NSGF).
weekly solutions for ILRS
The weekly ILRS products consist of SINEX files [IERS
Analysis Coordination] of weekly station coordinates and
daily Earth Orientation Parameters (x-pole, y-pole and excess
Length-Of-Day (LOD)) estimated from 7-day arcs (Sunday 00 UTC
to Saturday 24 UTC). Official ILRS Analysis Centers (AC) and
Combination Centers (CC) are tasked with the generation of the
products with individual and combined solutions respectively.
SLR observations on LAGEOS-1, LAGEOS-2, Etalon-1 and Etalon-2
are reduced in 7-day arcs to generate the individual EOP and
station positions solutions; the measurements are retrieved
from the official ILRS archives either at CDDIS and/or EDC archiving
facilities. The observations are reduced to generate a loosely
constrained solution for station coordinates and EOPs following
strict standards agreed upon within the ILRS Analysis Working
Group to provide high quality products consistent with the IERS
The time series of weekly ASI sinex file is available at CDDIS
named as asi.pos+eop.yymmdd.vxx.snx.Z.
ASI/CGS is both an ILRS Analysis Center and the ILRS Primary
More details can be found in International
Laser Ranging site.
and Monitoring of the time series submitted by the ILRS ACs and
by the Primary CC are available here.
daily solutions for ILRS
The daily ILRS products consist of SINEX files of weekly station
coordinates and daily Earth Orientation Parameters (x-pole,
y-pole and excess Length-Of-Day (LOD)) estimated each day
from 7-day arcs. Official ILRS Analysis Centers (AC) and Combination
Centers (CC) are tasked with the generation of the products
with individual and combined solutions respectively.
The solution is completely equivalent to the weekly solution
described in the previous paragraph. This rapid product, obtained
by increasing the generation frequency up to once per day and
hence labelled as ‘daily’, is characterized by a
sliding window of 7 day data analyzed daily, reducing the overall
potential product latency to 2 days. It is mainly produced to
provide frequent update of the EOPs