File: AAREADME.txt Version: NSSDC 11/15/2001 JFC ------------------------------------------------------------------------------ Hourly Interplanetary Magnetic Field Data from Pioneer Venus Orbiter: 1978 - 1988 Principal Investigator: Prof. Christopher T. Russell Univ. of California, Los Angeles ctrussell@igpp.ucla.edu Phone: (310) 206-3051 Date Coverage: 1978-12-06 to 1988-08-07 Data Set Description: This data set includes hourly averages of the interplanetary magnetic field magnitude and vector components measured by the Pioneer Venus Orbiter. The magnetic field data and spacecraft coordinates are provided in the Venus Solar Observer (VSO) system (see below). Data collection periods inside the Venusian bow shock have been removed and hour averages have computed for those data points. Note that the BT values are computed from magnitudes of high resolution (1/4 sec.) vectors and are actually overlapped two-hour averages computed every hour to avoid potential aliasing effects from non-overlapping averages. The vector component averages are also overlapped in the same manner. Also note that BT will generally be higher than the magnitude of the hour-average field vector, so the latter should not be used to compute magnitude. Data records for hours 8-10 of July 3, 1979 have been removed since the data values are erroneous. Two-minute overlapping averages without the bow shock cuts were previously archived at NSSDC as dataset 78-051A-12G for data from 1978-12-06 through 1984-09-30 (this data set now extends through 1992-10-08, the end of the PVO mission). Detailed questions on the removal procedure should be directed to Chris Russell. This data was supplied by Janet Luhmann (now at UC-Berkeley) and Muriel Kniffen of the UCLA PVO magnetometer team in support of PVO data archiving and the COHO program. A transformed version of this data set in heliographic & RTN coordinates may be found in COHO directory PIONEER_VENUS/MERGED and can also be plotted on-line using the COHOWeb system (see below). Data Format: 1 UT - Universal Time (YEAR MONTH DAY HOUR) 2 BX VSO - BX average (nanoteslas in VSO coordinates) 3 BY VSO - BY average (nanateslas in VSO coordinates) 4 BZ VSO - BZ average (nanateslas in VSO coordinates) 5 BT - B total average (nanoteslas) 6 VSOX - SC position X (Venus radii in VSO coordinates) 7 VSOY - SC position Y (Venus radii in VSO coordinates) 8 VSOZ - SC position Z (Venus radii in VSO coordinates) Venus Solar Orbital (VSO) coordinates are defined with respect to the orbital plane of Venus which is tilted about two degrees from the Ecliptic. The VSO system is Venus-centered with the X axis towards the Sun, the Y axis in the orbital plane and directed opposite to the planet's orbital motion, and the Z axis is northward and perpendicular to the orbital plane. Related Information and Data: Further details on the spacecraft, experiment, data sets at NSSDC, and related WWW sites can be found on the Pioneer Venus flight project page under http://nssdc.gsfc.nasa.gov/space/ Hour averages of the interplanetary solar wind data from, and hourly heliocentric coordinates of, Pioneer Venus Orbiter and other interplanetary spacecraft may be also be accessed and plotted on-line through the COHOWeb service based at the same WWW site as above. Acknowledgement: Use of these data in publications should be accompanied at minimum by acknowledgements of the National Space Science Data Center and the responsible Principal Investigator defined in the experiment documentation provided here.