Generic Trans-Neptunian Object (TNO) Ephemeris Files
                     B. Semenov -- October 20, 2022
                  
This folder contains SPICE format (SPK) versions of the most recent 
TNO ephemeris files produced by JPL's Solar System Dynamics Group. 

The naming schema for these files is usually 

  tnosat_vVVVx_IIIIIIII_jplSSS_YYYYMMDD.bsp

where:

  tnosat    indicates a TNO satellite system ephemeris file.

  VVV       is the TNO satellite solution version.
 
  x         is an optional sub-version of the solution.

  IIIIIIII  is the 8-digit NAIF ID of the TNO system barycenter.

  SSS       is the TNO system barycenter solution version.

  YYYYMMDD  is the file release date.

Each TNO satellite SPK includes data for the system barycenter, the main 
body and its satellites.

The NAIF IDs for all bodies are formed following the 8/9 digit 
extended asteroid NAIF ID schema:

  https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/req/naif_ids.html#Asteroids  

NAIF's SPK tutorial provides more information about barycenters, and about 
how to use (read) SPK files. That tutorial is found here: 
    
    http://naif.jpl.nasa.gov/naif/tutorials.html 

Each of these SPKs contains some meta-data in the comment area. Typically 
the meta-data are those provided by the person who generated the source 
file from which the SPK was made. (The Solar System Dynamics Group uses a 
local, internal format for their ephemeris files.) You may view those
meta-data by reading the comment area, using the "commnt" utility available 
in each Toolkit. Those same comments are often available in this folder, 
in files having a "cmt" extension.

The file named "aa_summaries" provides a convenient summary of the 
contents (which satellites are included) and time coverage for every SPK 
file available in this folder.

Older versions of satellite SPK files are found one level down, in the 
"a_old_version" folder.