PVO-V-OMAG-4-P-SENSOR-24SEC-V1.0 PVO VENUS MAG RESAMPLED P-SENSOR 24SEC AVGS V1.0 Dataset Overview This dataset contains resampled magnetometer data from the Pioneer Venus Orbiter spacecraft beginning with orbit 3602 (Oct 16, 1988) and continuing until the orbiter was lost in the Venusian atmosphere (orbit 5055, Oct 7, 1992). The dataset differs from the 2 spin period averaged mag dataset from the previous orbits due to an anomaly in the multiplexer that controled the sampling of the magnetometer sensors. During orbit 3602, and for the remainder of the mission, the spacecraft downlink contained magnetometer data from only the P sensor. The P sensor is the sensor which is aligned with the spacecraft spin axis, nominally in the direction of the ecliptic normal. After the anomaly was first detected, the magnetometer team made a substantial effort to recover the average magnetic field vector using the single sensor data. Since the sensor is not perfectly aligned with the spacecraft spin axis, a small amount of spin modulation is present in the sensor data. In theory, the amplitude of the spin plane field can be determined from the amplitude of the spin modulation and knowledge of the true sensor mounting geometry. In practice, this turned out to be a very difficult task because the spin axis of the spacecraft is not sufficiently constant in body-fixed coordinates. Data Processing and Sampling This dataset has been calibrated to account for gains only. The data are given in units of nanoTesla. The data have been derived from the high resolution dataset PVO-V-OMAG-3-RDR-PSENSOR-HIRES-V1.0 by resampling. These data have been averaged over two spin period intervals on one spin period centers. The time tag given to each record is the project assigned time value for the spin period (UADS time tag). The dataset contains the following columns: Column Description ___________________________________________________________________________ UT S/C event time (UT) of the sample Bz-SC Calibrated/Averaged value of S/C coord. Z component of B Var-Bz The variance of Bz-sc over the two spin period interval Bn The magnetic field magnitude |B|. Ancillary Products Other datasets on the CD-ROM are the Ephemeris which contains spacecraft position in Venus Solar Orbital coordinates, spacecraft altitude, solar zenith angle, Venus centered longitude and latitude, spacecraft spin axis components, celestial longitude and latitude of the spacecraft, celestial longitude of the earth, and the Sun-spacecraft range. Other ancillary datasets are the: 1) phase and offset which contains the phase amplitude of sun synchronous modulation of the 4 signals (E100, E730, E5.4 and E30K), and offsets of the G sensor. 2) The engineering dataset which contains temperatures, magnetometer modes, magnetometer sample format, magnetometer spin average select, telemetry data format, telemetry bit rate, spacecraft spin period, pulse time, the difference between the Sun pulse time and the Rip pulse time, and the pulse time flag. CONFIDENCE_LEVEL_NOTE These data have been reprocessed several times during the course of the mission. Each successive reprocessing has eliminated some of the problems found in earlier version of the data. Please bring to the attention of the original investigator any suspicious section of data. No zero level correction has been applied to the data. References: Russell, C.T., R.C. Snare, J.D. Means and R.C. Elphic, 'Pioneer Venus Orbiter Fluxgate Magnetometer', Ieee Trans. Geo. Elec., vol. GE 18, no. 1 p. 32, 1980. /* /* Elphic R.C., C.T. Russell, J.A. Slavin, L.H. Brace, and A.F. Nagy, 'The location of the dayside ionopause of Venus: Pioneer Venus Orbiter Magnetometer observations', Geophys. Res. Lett., vol. 7, no. 8, p. 561, 1980. /* Elphic R.C., C.T. Russell, J.A. Slavin, and L.H. Brace, 'Observations of the dayside ionopause and ionosphere of Venus', J. Geophys. Res., vol. 85, no. A13, p. 7679, 1980. /* Luhmann J.G., R.C. Elphic, C.T. Russell, and J.A. Slavin, 'Observations of large scale steady magnetic fields in the nightside Venus ionosphere and near wake', Geophys. Res. Lett., vol. 8, no. 5, p. 517, 1981. /* Russell C.T, J.G. Luhmann, and R.C. Elphic, 'The distant bow shock and magnetotail of Venus: Magnetic field and plasma wave observations', Geophys. Res. Lett., vol. 8, no. 7, p. 843, 1981. /* Elphic, R.C., C.T. Russell, and J.G. Luhmann, 'The Venus ionopause current sheet: Thickness length scale and controlling factors', J. of Geophys., vol. 86, no. A13, p. 11,430, 1981. /* Luhmann J.G., C.T. Russell, L.H. Brace, H.A. Taylor, W.C. Knudsen, F.L. Scarf, D.S. Colburn and A. Barnes, 'Pioneer Venus observations of plasma and field structure in the near wake of Venus', J. Geophys. Res., vol. 87, no. A11, p. 9205, 1982. /* Russell, C.T., J.G. Luhmann, and J.L. Phillips, 'The location of the subsolar bow shock of Venus: Implications for the obstacle shape', Geophys. Res. Lett., vol. 12, no. 10, p.627, 1985. /* Phillips,J.L., J.G. Luhmann, and C.T. Russell, 'Magnetic configuration of the Venus magnetosheath', J. Geophys. Res., vol. 91, no. A7 p. 7931, 1986. /* Saunders, M.A., and C.T. Russell, 'Average dimension and magnetic structure of the distant Venus magnetotail', J Geophys. Res., vol.91, no.A5 p.5589, 1986. /* McComas,D.J., H.E. Spence, C.T. Russell, and M.A. Saunders, 'The average magnetic field draping and consistent plasma properties of the Venus magnetotail' J. Geophys. Res., vol 91, no. A7, p. 7939, 1986. /* Phillips, J.L., and C.T. Russell, 'Upper limit on the intrinsic magnetic field of Venus', J. of Geophys. Res, vol. 93, no. A3, p. 2253, 1987. /* Russell, C.T., E. Chou, J.G. Luhmann, P. Gazis, L.H. Brace and W.R. Hoegy, 'Solar and interplanetary control of the location of the Venus bow shock', J. of Geophys. Res, vol. 93, no. A6, p. 5461, 1988. /* Russell,C.T., 'Magnetic flux ropes in the ionosphere of Venus', Geophysical Monograph, vol. 58, p. 413 /* Orlowski D.S., and C.T. Russell, 'ULF waves upstream of the Venus Bow Shock: Properties of one-hertz waves ', J. Geophys. Res., vol. 96, no. A7, p. 11271, 1991.