  I describe and present the results of a newly developed fitting methodology
optimized for very long time series. The development of this new methodology
was motivated by the fact that we now have more than half a decade of nearly
uninterrupted observations by GONG and MDI, with fill factors as high as 89.8%
and 82.2% respectively. It was recently prompted by the availability of a
2088-day-long time series of spherical harmonic coefficients produced by the
MDI team.
  The fitting procedure uses an optimal sine-multi-taper spectral estimator --
whith the number of tapers based on the mode linewidth, the complete leakage
matrix (i.e., horizontal as well as vertical components), and an asymmetric
mode profile to fit simultaneously all the azimuthal orders with individually
parametrized profiles.
  This method was applied to 2088-day-long time series of MDI and GONG
observations, as well as 728-day-long subsets, and for spherical harmonic
degrees between 1 and 25. The values resulting from these fits are
inter-compared (MDI versus GONG) and compared to equivalent estimates from the
MDI team and the GONG project. I also compare the results from fitting the
728-day-long subsets to the result of the 2088-day-long time series. This
comparison shows the well known change of frequencies with solar activity --
and how it scales with a nearly constant pattern in frequency and m/l. This
comparison also shows some changes in the mode linewidth and the constancy of
the mode asymmetry.
