Voyager Low Field Magnetometer Summary Record Format
LFM Record Components
Header block: 32 words
MAG data block: 496 words
SEDR data block: 40 words
---
568 words total (32 bit words)
Header Block Description
word type description
---- ---- -----------
1 A*4 Data Identifier ("LFM ")
2 A*4 Telemetry Format ("ENG ","CR-1","CR-2","CR-3","CR-4","CR-5",
"CR-6","CR-7","CR5A","GS-2","GS-3","GS-4",
"GS-6","GS-7","GS-8","GS10","G10A","OC-1",
"OC-2","UV5A","****")
3 A*4 S/C Identification ("FLT1","FLT2","PTM ","SIM1","SIM2","UKWN")
4 I*2 Year of Data
4.5 I*2 Day of Year (Jan. 1 = 1)
5 I*2 Hour of Day
5.5 I*2 Minute of Hour
6 I*2 Second of Minute
6.5 I*2 Millisecond of Second
7 R*8 Decimal Day of Year (Jan. 1 = 0)
9 R*8 Decimal Day Count since August 20, 1977
11 A*4 Time Type (SCET = spacecraft event time,
ERTS = start earth receive time)
12 R*4 Time period of data block (48 sec)
13 I*2 48 Minute Counter (2**16 sequence counter of data at time
of telemetry readout.)
13.5 I*2 48 Second Counter (Modulo 60 sequence counter of data at time
of telemetry readout.)
14 I*2 60 Millisecond Counter (Line counter of data at time
of telemetry readout.)
14.5 I*2 Spare
15 Z*4 MAG Status Word
16 Z*4 MAG Command Word
17 I*2 Data Identifier (LFM=2,HDR1=8)
17.5 I*2 Data Rate (GS-X=0,CR-1=1,CR-2=2,CR-3=3,CR-4=4,CR-5=5,
CR-6=6,CR-7=9,ENG=8,CR5A=13,UV5A=13)
* CR5A and UV5A are both VIM-5 modes
18 I*4 Spare
19 A*8 Data Confidence Flag (indicates reduced data confidence due to
software/hardware intervention)
21 I*4 Spare
22 I*4 Spare
23 I*4 Spare
24 I*4 Spare
25 I*4 Spare
26 I*4 Spare
27 I*4 Spare
28 I*4 Spare
29 I*4 Spare
30 I*2 Number of primary data words
30.5 I*2 Number of secondary data words
31 I*2 Number of primary full words
31.5 I*2 Number of secondary full words
32 I*2 Record number in file
32.5 I*2 Number of words remaining in logical record
MAG Data Block Description
48 second averages
------------------
33 R*4 F1: 48 second average of 9.6 second norms (nT)
34 R*4 F2: Norm of 48 second component averages (nT)
35 R*4 Latitudinal field angle = arcsin(B1/F2) (degrees)
36 R*4 Longitudinal field angle = 180 - atan(B2,-B1) (degrees)
37 R*4 B1: 48 second average of first 9.6 second averaged component (nT)
38 R*4 B2: 48 second average of second 9.6 second averaged component (nT)
39 R*4 B3: 48 second average of third 9.6 second averaged component (nT)
40 R*4 RMS of B1 (nT)
41 R*4 RMS of B2 (nT)
42 R*4 RMS of B3 (nT)
43 I*4 Number of 9.6 averages per 48 second average
9.6 second averages
-------------------
44-48 5(R*4) F1: 9.6 second averages of 1.92 second norms (nT)
49-53 5(R*4) F2: Norms of 9.6 second component averages (nT)
54-58 5(R*4) Latitudinal field angle = arcsin(B1/F2) (degrees)
59-63 5(R*4) Longitudinal field angle = 180 - atan(B2,-B1) (degrees)
64-68 5(R*4) B1: 9.6 second average of first 1.92 second averaged component (nT)
69-73 5(R*4) B2: 9.6 second average of second 1.92 second averaged component (nT)
74-78 5(R*4) B3: 9.6 second average of third 1.92 second averaged component (nT)
79 R*4 RMS of B1 (nT)
80 R*4 RMS of B2 (nT)
81 R*4 RMS of B3 (nT)
. . .
. . . 5 sets of (B1,B2,B3) triplets
. . .
91 R*4 RMS of B1 (nT)
92 R*4 RMS of B2 (nT)
93 R*4 RMS of B3 (nT)
94-98 5(I*4) Number of 1.92 averages per 9.6 second average
1.92 second averages
--------------------
99-123 25(R*4) F1: 1.92 second average of detail norms (nT)
124-148 25(R*4) F2: Norm of 1.92 second component averages (nT)
149-173 25(R*4) Latitudinal field angle = arcsin(B1/F2) (degrees)
174-198 25(R*4) Longitudinal field angle = 180 - atan(B2,-B1) (degrees)
199-223 25(R*4) B1: 1.92 second average of first detail component (nT)
224-248 25(R*4) B2: 1.92 second average of second detail component (nT)
249-273 25(R*4) B3: 1.92 second average of third detail component (nT)
274 R*4 RMS of B1 (nT)
275 R*4 RMS of B2 (nT)
276 R*4 RMS of B3 (nT)
. . .
. . . 25 sets of (B1,B2,B3) triplets
. . .
346 R*4 RMS of B1 (nT)
347 R*4 RMS of B2 (nT)
348 R*4 RMS of B3 (nT)
349-373 I*4 Number of detail points per 1.92 second average
S/C field averages
------------------
374-520 Z*4 spare words
521 R*4 RMS of first 48 second averaged s/c field component (nT)
522 R*4 RMS of second 48 second averaged s/c field component (nT)
523 R*4 RMS of third 48 second averaged s/c field component (nT)
524 I*4 Number of 9.6 s/c field averages per 48 second average
525 R*4 48 second average of first s/c field component (nT)
526 R*4 48 second average of second s/c field component (nT)
527 R*4 48 second average of third s/c field component (nT)
528 R*4 Norm of 48 second s/c field component averages (nT)
SEDR Data Block Description
---------------------------
529-530 R*8 TN: Epic day of navigation block "closest" to data time
531-532 R*8 TP: Epic day of pointing vector block "closest" to data time
533 R*4 s/c X position component (A.U. or planetary radii *)
534 R*4 s/c Y position component (A.U. or planetary radii *)
535 R*4 s/c Z position component (A.U. or planetary radii *)
536 R*4 s/c X velocity component (km/s)
537 R*4 s/c Y velocity component (km/s)
538 R*4 s/c Z velocity component (km/s)
539 R*4 s/c distance (A.U. or planetary radii *)
540 R*4 s/c longitude (radians *)
541 R*4 s/c latitiude (radians *)
542-550 R*4 Matrix 1
551-559 R*4 Matrix 2
560-568 R*4 Matrix 3
Notes:
* Spacecraft position data is dependent upon the coordinate system selected
during EDR processing. The HDR1 record contains this information at word
number 13. Valid coordinates are HG (heliographic), S3 (Jupiter planetary
system), L1 (Saturn planetary system), U1 (Uranus planetary system) and
N1 (Neptune planetary system). During cruise processing (HG), the spacecraft
location is based upon the Inertial Heliographic system (IHG). During
encounter processing (S3, L1, U1, N1), the spacecraft location is based upon
planocentric system coordinates.
