[IGSMAIL-6588] Issue with recent IGS final LODs

[Paul Rebischung]

Dear Colleagues,

Since GPS week 1671, the IGS final LODs, obtained through the
combination of the Analysis Center SINEX solutions, have been affected
by an issue in our preprocessing of the NGS solutions. As a result, NGS
LOD estimates have overwhelmed the IGS combined LODs since that time.

This issue will be fixed in the next SINEX combination (week 1686). We
have also resubmitted corrected products to the global data centers for
weeks 1671 to 1685.

For information, the differences over weeks 1671-1685 between the new,
corrected combined LODs and the old ones range between -22 us and +35
us, with a mean of -1 us and std. dev. of 10 us. The other products of
the SINEX combinations (pole coordinates, pole coordinate rates and
station positions) are not significantly changed (differences of a few
uas, a few 10 uas/d and below 0.1 mm, respectively).

With apologies for the inconvenience,

Paul Rebischung