The sensor providing data here (called EFD-P in Geotail
Prelaunch Report, April 1992) measures the difference of
electric potential between two electrodes (probes) immersed
in the plasma. There are two sperical probes and two wire
antennas each of which is extended by 50 meters from the
satellite in its rotational plane. The two sperical probes
are opposite each other (100 meters tip-to-tip) as are the
two wire antennas. The probe pairs are orthogonal to each
other. Diving the potential difference by the distance
between the probes or the centers of the conducting portion
of the wire antennas gives the electric field component along
the probe extension. The measurement of the electric field in
the satellite rotational plane gives the vector electric
field when the electric field along the magnetic field is
much smaller than the perpendicular component.
- Prior to March 8, 1993, the >34keV electron
anisotropy parameters a1, a2, phi1, and phi2 are not useable.
After this date, all electron intensity and anisotropy data
are not useable due to EPIC key parameter software
calibration problems.
- A small subset of the ICS key parameters are not
correct because the EPIC KP software failed to recognize when
the instrument was in a reduced aperture or calibration mode.
Please contact Dr. Richard McEntire at
richard_mcentire@jhuapl.edu or (301)953-5410 or Dr. Tony Lui
at anthony_lui@jhuapl.edu or (301)953-6000, ext. 8407 to
verify whether your periods of interest are affected.
- In periods of low flux, the 96-second averaging
interval is insufficient for calculating meaningful
anisotropy measurements. Large values of a1 and a2 and random
values of phi1 and phi2 result.
- Not all aspects of the STICS key parameters have
been fully validated.
- Several miscellaneous corrections are needed to the
EPIC KP CDF file meta information:
- The range of all phi1 and phi2 anisotropy
parameters should be -pi to +pi, not 0.0 to 2pi.
- The range of all a1 and a2 anisotropy
parameters should be 0.0 to 2.1, not 0.0 to 2.0.
- The lower bounds of the two STICS proton
differential intensity energy bands are not correct. For the
given center values of 9.38 and 22.86 keV, the minus values
to specify the lower limits of the bands should be 0.11 keV
and 0.27 keV, respectively, not 0.3 keV and 0.0 keV,
respectively.
- ICS Ion channels can change between two sets of
energy pass bands from record to record; consult the
associated energy information to determine what the current
values are. Anisotropy Calculation Qualification: A) a1, a2,
phi1 and phi2 are not calculated when the count rate is below
a threshhold, currently 8 counts/96 seconds.
- supplied by Stewart Nylund (ISTP::NYLUND)
HPA 1-min data are provisional until calibrations are corrected for
long-term drift. Also, caution is advised for occasional telemetry
errors.