Fundamental Technologies

Voyager LECP Pages


February 2, 1982

TO:  Voyager LECP Team Members

FROM:  J. F. Carbary

SUBJECT:  GSFC MAG Data and Merged NAV-MAG Data


The GSFC magnetometer team has recently made available to us the Saturn encounter MAG data.  The data have a time resolution of 48S and cover the time intervals:

VGR 1 1980-317-00:00
VGR 2 1981-237-00:00

The MAG data are given in the spacecraft payload (PLD) system - not the usual heliographic (RTN) system.  The experimenters must take care to make the necessary transformations.  The PLD data are in the same positions on a MAG tape as the usual RTN data were.

In addition, tapes have been created which contain merged navigation (NAV) and MAG data at a 48S time resolution.  These NAVMAG tapes are FB, 1600 BPI and have the following record format:


1 I*2 YY 2 digit year
2 I*2 DDD Day of year (Jan 1 = 1)
3 I*2 HH Hour of day
4 I*2 MM Minute of hour
5 I*2 SS Second of minute
6 I*2 II Spare
7-10 R*8 TSEC Seconds since 1977.000.00
11-16 R*4 R(3) Spacecraft X,Y,Z in STN frame* in RS**
17-22 R*4 B(3) Magnetic field Bx, By, Bz in STN frame* in g
23-40 R*4 TM(3,3) Transform matrix from LECP frame*** to STN frame*
41-42 R*4 LON Spacecraft SLS longitude**** in degrees
43-44 R*4 LAT Spacecraft latitude in degrees
45-50 R*4 SPR Spares


* The STN frame is similar to the solar ecliptic frame used at earth. In the STN system, Z points along the spin axis of Saturn, X points sunward in the meridian defined by Z and the planet-sun line, and Y completes the RH system.
** 1 RS = 60000 km. Users may wish to convert to 1 RS = 60330 km, in which case the conversion factor is 0.99453.
*** The LECP frame is the scan frame of the instrument with Z along the stepper axis, X along the centerline of sector 8, and Y along the centerline of sector Z.
**** Desch and Kaiser, Geophys. Res. Lett., 8, 253, 1981.
DEC compatible software is available to read and average these tapes.

NAV-MAG File Format

2   DDD
3   HH
4   MM
5   SS
6   spare
8   sec
  11 1  

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Last modified 5/12/05, Tizby Hunt-Ward
Original page by I. Robertson