Weekly station positions aligned to the IGS reference frame are generated for the whole SIRGAS-CON network (SIRGAS-C core network + SIRGAS-N national reference networks) after combining the loosely constrained weekly solutions delivered by the SIRGAS Processing Centres. An IGS reference frame corresponds to a subset of ITRF positions and velocities for a selected set of GNSS reference stations used as the fiducial points for the determination of the IGS satellite orbits, satellite clocks offsets, and Earth orientation parameters as well as the corrections for the phase centre variations (PCV) at both transmitting and receiving GNSS antennas. As globally there is no translation, rotation or scale difference between both ITRF and IGS reference frame, products referring to the latter are considered to be nominally in the ITRF. According to the current practice, the publication of a new ITRF is quickly followed by the release of an updated IGS reference frame solution, which profits from the improved ITRF solution and the update of the GNSS PCV models. The SIRGAS weekly processing refers to the same IGS reference frame, in which the satellite orbits are determined.
The file names correspond to cccyyPwwww:
ccc identifies the combination centre (IBG: IBGE, SIR: IGS RNAAC SIRGAS),
yy represent the last two digits of the year,
P stays for GPS(GNSS) technique,
wwww is the GPS week.
Weekly solutions computed before GPS week 1400 (November 4, 2006) were reprocessed including absolute corrections for the phase center variations of the GNSS antennae (see [IGSMAIL-5189], [IGSMAIL-5272]) and applying IGS05 as reference frame (see [IGSMAIL-5438], [IGSMAIL-5447], [IGSMAIL-5455]). These reprocessed solutions are identified with si1yyPwwww.crd.
Weekly station positions from October 7, 2012 (GPS week 1709) to January 28, 2017 (GPS week 1933) refer to the IGb08 frame (see [IGSMAIL-6663]).
Weekly station positions from January 29, 2017 (GPS week 1934) to May 16, 2020 (GPS week 2105) refer to the IGS14 frame (see [IGSMAIL-7399]).
Weekly station positions after May 17, 2020 (GPS week 2106) refer to the IGb14 frame, an updated version of IGS14 (see [IGSMAIL-7921]).
Files with extension crd contain the final weekly SIRGAS-CON positions. Files with extension SUM are the corresponding reports.
Week Epoch IBGE Combination IGS-RNAAC-SIR combination
2104 2020-05-06 (2020.35) ibg20P2104.crd IBG2104S.SUM sir20P2104.crd SIR21047.SUM
2105 2020-05-13 (2020.37) ibg20P2105.crd IBG2105S.SUM sir20P2105.crd SIR21057.SUM
2106 2020-05-20 (2020.39) ibg20P2106.crd IBG2106S.SUM sir20P2106.crd SIR21067.SUM
Solutions for previous weeks are available at:
ftp.sirgas.org/pub/gps/SIRGAS/ ... wwww ... (wwww= GPS week)