What

1
Whats New ?

• Better ambiguity resolution
• LC_AUTCLN now robust for all data with good
  pseudorange from 1994
• gt 90 resolution after 2004, 80 2001, 70 1996
  
• LC_HELP should be equivalent for small networks
• IAU2000 replaces IAU1980 nutation model
• Primary accuracy difference is in UT1 estimation
  (not relevant for regional studies)
• Cannot use g-files created with a different model
  (use SP3 or change nutabl link)

2
Whats New ?

• Better IGS orbits
• Can run GAMIT (and GLOBK) with IGSF orbits fixed
  (BASELINE not RELAX)
• IGSF (from SP3 files) now default, not SIOF (from
  g-files)
• No discernible orbital error to 4000 km for data
  since at least 2004
• Reprocessed orbits available later in 2009
• Reprocessed global h-files available from MIT and
  SOPAC
• Primary improvement is global ambiguity
  resolution
• MIT files up to 300 global sites
• SOPAC files up to 200 global sites plus regional
  networks
• sh_get_hfiles allows selection of MIT
  reprocessed, SOPAC reprocessed, or SOPAC
  operational
• Note scale discontinuity at GPS Week 1400
  (November 2008) with current IGS orbits and SOPAC
  operational h-files due to change to absolute
  PCVs

3
Quality of IGS Final Orbits 1994-2008 20 mm
1 ppb Source
http//acc.igs.org
4
Whats New ?

• Better models for atmospheric propagation effects
• GPT replaces standard temperature and pressure
  for a priori ZHD
• GMF replaces NMF for mapping functions
• VMF1 ZHD and mapping functions from numerical
  weather models available as grid
• Atmospheric loading ( ATML ) corrections
  available
• Gridded values available from T van Dam at
  Luxemburg University and distributed on
  GAMiT/GLOBK ftp site (everest.mit.edu)
• Should be used in conjunction with VMF1 ZHD
• Sub-daily ( thermal tide ) components not yet
  handled correctly