https://spdf.gsfc.nasa.gov/pub/data/pioneer/pioneer10/particle/gtt/ip_15min_ascii/aareadme.txt
This directory contains half-year files of 15-min count rates and
related parameters from the the Geiger Tube Telescope (GTT) flown
on Pioneer 10. The data were initially provided to NSSDC by the
GTT team at U. Iowa in VMS binary format on magnetic tapes. They
have been converted to ASCII format at GSFC/SPDF, with an almost
complete retention of the original sequence of words in the data
records. (Only unused words were dropped, and the spacecraft ID
was moved.) The data, and their binary format, are extensively
discussed at
https://spdf.gsfc.nasa.gov/pub/data/pioneer/pioneer10/particle/gtt/aavoldesc.sfd.
The format of the ASCII data contained in this directory follows:
Length of record =1445bytes + LF
Item number Format Function
1 A24 ASCII timecode format of start
time (in spacecraft event time)
2 Note 1 I5 Year of Data 72,73 ...(ERT)
3 Note 1 I4 Day of Data (ERT)
4 Note 2 F11.8 Beginning Day Fraction (ERT)
5 F11.8 Ending Day Fraction (ERT)
6 I3 Spacecraft ID (10 or 11)
7 Note 3 I4 Length of Period in Minutes
8 Note 4 I4 Period Type
9 I4 Number of samples this interval
10-21 Note 5 12E13.5,1x Effective Counts
22-33 12E13.5,1x (Sum of Raw Counts)/.09375
34-45 12E13.5,1x Counting Rate Ave in Counts/sec
46-57 12E13.5,1x Sigma (Standard Deviation)
58-69 Note 6 12E13.5,1x M Fourier Coefficients
70-81 12E13.5,1x K " "
82-93 12E13.5,1x D " "
94-105 12E13.5 Sum of Raw Counts
106 I5 Number of Errors this Interval
107 Note 7 F11.3 Day and Day Fraction since 1950.0
108 F11.3 Radius to SC from earth in AU
109 F9.3 Earth-Sun distance in AU
110 F9.3 Radius to SC from the Sun in AU
111 Note 8 F9.3 Celestial Longitude of Earth
112 Note 8 F9.3 Celestial Longitude of SC
113 Note 9 F9.3 Longitude of Solar Equator + 270
114 Note 8 F15.11 Celestial Latitude of Earth
115 Note 8 F11.7 Celestial Latitude of SC
116 Note 9 F11.7 Heliographic Latitude of SC
117 Note 9 F11.7 Heliographic Latitude of Earth
Note 1: Earth received time (ERT) for the data.
Note 2: Beginning time is the time of the first data point
found in the interval. The Ending time is the
time of the last data point in the interval.
Note 3: This number will be the number of minutes in the
interval since these are quarter hour averages
the number will be 15.
Note 4: This is a number assigned to describe the
accumulation period; for quarter hour averages
it will be 1.
Note 5: Items 10 through 105 represent 8 sets of values. The
order of the detectors are as follows:
Position Detector
1 G
2 A
3 B
4 G
5 AB
6 ABC
7 C
8 D
9 ABC
10 DEF
11 G + G
12 ABC + ABC
Note 6: The Fourier Coefficients are used in the following
formula.
F(phi) = M ( 1 + K Cos ( phi - D ) )
Note 7: This time is spacecraft event time for the center
time of the data used in the sum.
Note 8: The celestial latitude and longitude are measured in
a reference system using the Sun as the reference body
body and the true ecliptic of date as the reference
plane.
This plane contains the vernal equinox and the
longitudes are measured eastward from the line
between the vernal equinox and the Sun. The latitudes
are measured from the plane. Northward being positive.
Note 9: Calculated quantities.
Inclination of solar equator to ecliptic, I=7.25
degrees. Longitude of the ascending node of the
solar equator on the ecliptic
Omega=73 degrees+40 minutes +50.25*t seconds
where t is the time in years reckoned from 1850.0 .
Reference: Explanatory Supplement to the Astronomical
Ephemeris and the American Ephemeris and Nautical
Almanac, 1961, page 307.
Note 10: All positional coordinates are referred to the
equinox/ecliptic of date.