DESCRIPTION OF THE OMNI DATA SET:
Data Availability
Comments
Spacecraft Identifiers
Description of the Coordinate Systems
Activity Indices
Crossnormalization of Parameters
The OMNI table is a part of "Heliosphere" database supported by the
Institute of Cosmophysical Research and Aeronomy SB RAS, Yakutsk, Russia. All the data in
this table and the description were taken from U.S. National Space Science Data Center.
The OMNI table contains the hourly mean values of the interplanetary magnetic field (IMF)
and solar wind plasma parameters measured by various spacecraft near the Earth's orbit, as
well as geomagnetic and solar activity indices, and energetic proton fluxes. 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.
From (Date) 
To (Date) 
From (Bartels r.n.) 
To (Bartels r.n.) 

IMF  Nov 27 1963  Nov 30 1999  1783  2271 
Plasma  Nov 27 1963  Dec 19 1999  1783  2271 
Geomag.Activity  Nov 02 1963  Nov 30 1999  1783  2271 
DST indices  Nov 02 1963  Dec 31 1997  1783  2245 
Provisional DST  Jan 01 1998  Sep 30 1999  2245  2268 
Particle Fluxes  Jan 01 1973  Dec 16 1998  1907  2258 
All the data in this table and description were taken from U.S. National Space Science Data Center.
Flag1 meanings:
flag1 = 0  No flag1 value in original data
flag1 = 1  IMF and Plasma data, same spacecraft
flag1 = 2  IMF and Plasma data, different spacecraft
flag1 = 3  No Plasma data
flag1 = 4  No IMF data
flag1 = 5  No IMF or Plasma data
Sigma B is sqrt((sigma Bx)^2 + (sigma By)^2 +(sigma
Bz)^2)
The sigma B values were not provided with HEOS IMF
data, i.e. for such records the words 2123 of the original OMNI data set (fields sigma_bx,
sigma_by, sigma_bz of this table) contain sigmaB (repeat word 19 or sigma_bmod),
sigma theta B and sigma phi B in degrees respectively.
Flag2 meanings:
flag2 = 0  there are no Proton Flux data, or all of the Proton Flux data are
contaminated by the magnetospheric events
flag2 = 1  then the channels >1,>2,>4,>10,>30 Mev were judged to
have magnetospheric 'contamination'
flag2 = 2  then the channels >1,>2,>4,>10 Mev were judged to have
magnetospheric 'contamination'
flag2 = 3  then the channels>1,>2,>4 Mev were judged to have
magnetospheric 'contamination'
flag2 = 4  then the channels >1,>2 Mev were judged to have magnetospheric
'contamination'
flag2 = 5  then the channels >1 Mev channels were judged to have magnetospheric
'contamination'
flag2 = 6  then no channel was judged to have magnetospheric 'contamination'
flag2 = 1  then not checked for magnetospheric relevant after 88/306.
Spacecraft Name  ID 
IMP 1 (Expl 18)  18 
IMP 3 (Expl 28)  28 
IMP 4 (Expl 34)  34 
IMP 5 (Expl 41)  41 
IMP 6 (Expl 43)  43 
IMP 7 (Expl 47)  47 
IMP 8 (Expl 50)  50 
AIMP 1 (Expl 33)  33 
AIMP 2 (Expl 35)  35 
HEOS 1 and HEOS 2  1 
VELA 3  3 
OGO 5  5 
Merged LANL VELA Speed Data (July 1964  March 1971)  99 
Merged LANL IMP T,N,V (Including all IMP 8 LANL Plasma)  98 
ISEE 1  11 
ISEE 2  12 
ISEE 3  13 
PROGNOZ 10  10 
WIND  51 
No spacecraft  0 
DESCRIPTION OF COORDINATE SYSTEMS:
The Heliographic Inertial (HGI) coordinates are Suncentered and inertially fixed with
respect to an Xaxis 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 74.367 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 Yaxis completes the righthanded 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 the R and T axes. At zero heliographic
latitude, when the spacecraft is in the solar equatorial plane, the N and solar rotation
axes are parallel.
Convention for Latitude and Longitude Angles:
Latitude and longitude angles of solar wind plasma flow are generally measured from the radius vector away from the Sun. In all cases, latitude angles are positive for northgoing flow. The flow longitude angles have been treated differently for the nearEarth data, i.e. the OMNI, and for the deep space data. The flow is positive for the nearEarth data when coming from the right side of the Sun as viewed from the Earth, i.e. flowing toward +Y from X GSE or opposite to the direction of planetary motion. On the other hand, the flow longitudes for the deep space spacecraft use the opposite sign convection, i.e. positive for flow in the +T direction in the RTN system.
ACTIVITY INDICES:
The OMNI data set contains daily sunspot numbers and three geomagnetic activity indices:
Kp (3hr), C9 (24hr), and Dst (1hr). The multihour
indices are distributed into the relevant 1hour OMNI records.
The Dst index is calculated at Kyoto University. Recent improvements have included quickly
released provisional values. See http://swdcdb.kugi.kyotou.ac.jp/dstdir/index.html.
OMNIweb now includes Provisional Dst values as noted in the Data
Availability section above. The provisional values are replaced with the final values
as soon as they become available (in oneyear segments).
The Kp index is calculated at NGDC. The OMNI convention is to multiply the value by 10.
This transforms, for example, 3+ to 33 and 4 to 37.
CROSSNORMALIZATION OF PARAMETERS:
Note that, as discussed in the paper data books, crossnormalization of parameters
obtained from different sources has been done to yield more
multisource uniformity and to allow comparison of parameters. For data later than 1971,
only plasma density and temperature values have been
normalized. No implication about which data set is "correct" is implied; the
historical choice was to normalize to the IMP8/LANL data. For the
post1971 period the normalization equations used were (from Table 9 of Data Book
Supplement 3, NSSDC 8604):
For IMP8/LANL  no normalization 
For IMP8/MIT  (log N)norm = 0.12 + 0.89*(log N)obsvd (log T)norm = 0.62 + 1.11*(log T)obsvd 
For ISEE3  (log N)norm = 0.20 + 0.83*(log N)obsvd (log T)norm = 0.55 + 1.07*(log T)obsvd 
For ISEE1  (log N)norm = 0.18 + 0.85*(log N)obsvd (log T)norm = (log T)obsvd 
ACKNOLEWDGEMENT:
Acknowledgements to the National Space Science Data Center OMNIWeb database as the
source of data used in publications is requested. Copies of preprints or reprints of
OMNIbased publications sent to Joseph King (address below) would be appreciated for
tracking purposes.
For questions about this data set, please contact:
Dr. Joseph H. King, Code 633, Goddard
Space Flight Center, Greenbelt, MD, 20771.
Dr. Natalia Papitashvili, Code 633,
Goddard
Space Flight Center, Greenbelt, MD, 20771.