Satellite Laser Ranging in 5x5 Spherical Harmonics

This is a variant of the weekly, 5x5 SLR product created at the University of Texas’s Center for Space Research (CSR) which is released alongside the GRACE series:

ftp://podaac.jpl.nasa.gov/allData/tellus/preview/L2/deg_5/CSR.Weekly.5x5.Gravity_Harmonics.txt. 

The version here is averaged monthly, rather than weekly, to make it more directly comparable to the monthly GRACE data.  It contains an estimate of C₆₁/S₆₁ (but no other degree-6 harmonics) to avoid skewing the C_­21 harmonic due to a lack of sufficient degrees of freedom during the creation of the SLR gravity product (Cheng and Ries, 2017).  From January - November 1993, only four satellites were used in its creation (Starlette, Ajisai, and Lageos 1 and 2).  After that point, Stella was added as well.  Data exists through mid-2017.

The layout of the files contains a header section followed by one line containing the date for the following lines, and then 22 lines of spherical harmonic data.  The time lines are formatted as:  IARC, MAXDEG, NP, IYEAR, IM, XMJD:
       IARC: the arc number (ie: month number) 
       MAXDEG: spherical harmonic maximum degree/order of the field   
       NP:  number of coefficient pairs (Cnm & Snm)
       IYEAR:  year
       IM:  month
       XMJD: epoch of the arc at the first day in modified Julian date

The data lines are formatted as:  N, M, Cnm, Snm, Cnm-sigma, Snm-sigma:
      N:  spherical harmonic degree 
      M:  spherical harmonic order
      Cnm:  C coefficient 
      Snm:  S coefficient
      Cnm-sig:  The formal errors of the C coefficient
      Snm-sig:  The formal errors of the S coefficient