PDS_VERSION_ID        = PDS3                                                  
RECORD_TYPE           = STREAM                                                
OBJECT                = TEXT                                                  
  PUBLICATION_DATE      = 2009-02-01                                          
  NOTE                  = "GEOMINFO.TXT describes the geometry data           
                           available on this volume."                         
END_OBJECT            = TEXT                                                  
END                                                                           
                                                                              
The GEOMETRY directory contains ORBFACTS.TAB, an ASCII file that              
summarizes orbit information for the time period of the data. This            
information includes orbit number; periapsis data (time, spacecraft           
clock, longitude and latitude of spacecraft and Sun, altitude, and            
Mars-Sun distance); and apoapsis time. The data columns in ORBFACTS.TAB       
are indicated by column headings.                                             
                                                                              
The GEOMETRY directory also contains the following kernel files, which        
are ASCII text files.                                                         
                                                                              
     MAG_ER.TI,    a SPICE MAG/ER instrument kernel containing a MAG/ER       
                   instrument mounting description. (JPL NAIF)                
                   This file defines the various coordinate systems           
                   associated with the spacecraft and the mounting            
                   positions for the MAG and ER.  ASCII drawings are          
                   included.                                                  
                                                                              
     PCK.TPC,      a "planetary constants" (PCK) kernel file, which           
                   contains constants needed by NAIF subroutines              
                   which require body size, orientation, etc. (JPL NAIF)      
                   Any coordinate system transformation to body fixed         
                   or quasi body fixed coordinates consults this file.        
                   It will be altered from time to time as deemed             
                   necessary by NAIF.                                         
                                                                              
     MO_MAGS.KER,  a magnetometer constants file used for conversion          
                   of telemetry.                                              
                                                                              
     MO_OBJ.KER,   a file that provides information about program             
                   variables used in preparation of the data.                 
                   (GSFC MAG)                                                 
                                                                              
     SCLK.KER,     a spacecraft clock kernel file for the time                
                   period spanned by the data. (JPL NAIF)                     
                   This is one of two files needed to convert spacecraft      
                   tics - the long binary word in the header, roughly         
                   equal to seconds past a specific date - to Universal       
                   Time. This file will change from time to time.             
                                                                              
     LEAP.KER,     a "leapseconds" file; contains time conversion             
                   data needed by NAIF subroutines.  (JPL NAIF)               
                   This is a short file that contains a list of leapseconds,  
                   also needed to convert spacecraft tics to UTC.             
                                                                              
     HGA.TF,       a Frames Kernel file (FK); contains set of frame           
                   definitions for the Mars Global Surveyor                   
                   Surveyor High and Low gain antennas.  (JPL NAIF)           
                                                                              
     SC_MOD.KER,   Spacecraft Magnetic Field Model File for Mars Global       
                   Surveyor. (GSFC MAG)         

The NAIF node of the Planetary Data System (PDS) maintains an archive of      
SPICE kernel files, which contain ancillary geometry data for planetary       
missions. NAIF also maintains software for the utilization of SPICE           
data. For further information on NAIF and SPICE data, consult the NAIF        
Website at http://pds.jpl.nasa.gov/naif.html.                                 
                                                                              
Besides the files mentioned above, the GEOMETRY directory contains two        
image files, MGS_ER_1.JPG and MGS_ER_2.JPG, which show the geometry of        
the ER instrument on the MGS spacecraft. As their filename extensions         
indicate, these files are in JPEG format. These files were provided by        
Dr. David Mitchell.                                                           
                                                                              
The GEOMETRY directory also contains a detached PDS label for each of         
the above mentioned files.  The label describing a given file has the         
same filename as the file, but with the extension changed to LBL (for         
example, ORBFACTS.LBL).                                                       
                                                                              
Additional spacecraft ephemeris data are contained in the magnetic field      
data in Sun-State (like GSE) and Planetocentric coordinates. These data       
can be found in the MGS Level 1 Magnetometer data (PDS data set IDs
MGS-M-MAG-3-MAP1/FULLWORD-RES-MAG-V1.0 and 
MGS-M-MAG-3-PREMAP/FULLWORD-RES-MAG-V1.0).