File: ulymgd.txt
------------------------------------------------------------------
MERGED ULYSSES DATA DESCRIPTION
This directory contains hourly averages of parameters for the
interplanetary magnetic field, solar wind plasma, and spacecraft
trajectory coordinates.
Principal Investigator of magnetic field data: Dr. A. Balogh,
Imperial College, London, UK
Principal Investigator of plasma data, Dr. John L. Phillips
Los Alamos National Laboratory
ULYSSES data have been reprocessed to ensure a uniformity of
content and coordinate systems relative to data from other deep-
space missions:
- All spacecraft trajectory data were transformed to a Heliographic
Inertial (HGI) coordinate system.
- calculation of RTN Spherical components of the solar wind velocity from
RTN cartesian components:
- merging of trajectory coordinates, magnetic field data, and plasma data
files into a single annual file ULY_YR.DAT, where YR is the year;
- Data gaps were filled with dummy numbers for the missing hours or entire
days to make all files of equal length. The character '9' is used to
fill all fields for missing data according to their format, e.g.
' 9999.9' for a field with the FORTRAN format F7.1. Note that format F7.1
below really means (1X,F6.1),etc.
Note that an COHOWeb interface to this dataset, providing data
subsetting and and graphical browsing, is available at
"http://cohoweb.gsfc.nasa.gov/"
For the daily resolution data (one file), simple averages were taken over
the hourly values. The format is identical to that for the hour averages
However, the "hour" field has 0 as a value.and the "Magnitude of Average
Vector" field is the simple average of the 24 hourly values of this parameter.
FORMAT DESCRIPTION
WORD ASCII MEANING UNITS/COMMENTS
1 I4 Year 1992, 1993, etc.
2 I4 Decimal Day January 1 = Day 1
3 I3 Hour 0,1,...,23
4 F7.2 Spacecraft Heliographic Astronomical units
distance
5 F7.1 Heliographic Inertial latitude Degrees, +/-90.
of the Spacecraft
6 F7.1 Heliographic Inertial longitude Degrees, 0-360
of the Spacecraft
7 F7.2 BR RTN-Coordinate System nanoteslas
8 F7.2 BT RTN-Coordinate System nanoteslas
9 F7.2 BN RTN-Coordinate System nanoteslas
10 F7.2 Field Magnitude Average |B| 1/N SUM |B|, nT
(B-scalar)
11 I5 Number of vectors for Number
Mag field to the average
12 F7.1 Plasma flow speed, RTN km/s
13 F7.1 THETA-elevation angle degrees
of flow velocity vector
(RTN-cordinate system)
14 F7.1 PHI- azimuth angle of degrees
flow velocity vector.
(RTN-coordinate system) .
15 F9.5 Proton density [n/cc]
16 F9.5 Alpha density [n/cc]
17 F9.0 Proton Temperature (Large) degrees, K
18 F9.0 Proton Temperature (Small) degrees, K
The difference between T (Large) and T (Small) is discussed at
ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/ulysses/plasma/swoops/
ion/swoops_ion_users_guide_update_20030214.txt
DESCRIPTION OF COORDINATE SYSTEMS
The Heliographic Inertial (HGI) coordinates are Sun-centered and inertially
fixed with respect to an X-axis directed along the intersection line of
the ecliptic and solar equatorial planes. The solar equator plane is
inclined at 7.25 degrees from the ecliptic. This direction was towards
ecliptic longitude of 74.36 degrees on 1 January 1900 at 1200 UT;
because of precession of the celestial equator, this longitude increases
by 1.4 degrees/century. The Z axis is directed perpendicular and northward
from the solar equator, and the Y-axis completes the right-handed set. This
system differs from the usual heliographic coordinates (e.g. Carrington
longitudes) which are fixed in the frame of the rotating Sun.
The RTN system is fixed at a spacecraft (or the planet). The R
axis is directed radially away from the Sun, the T axis is the cross
product of the solar rotation axis and the R axis, and the N axis is the
cross product of R and T. At zero Heliographic Latitude when the
spacecraft is in the solar equatorial plane the N and solar rotation axes
are parallel.
------------------------------------------