Analysis of IMP-8 Data
Nov. 1-5, 1993
NOV. 1:
- IMP-8 is initially in the solar wind. At about 1830 UT there is a
brief excursion into the magnetosheath as evidenced by a brief tripling
of the magnetic field from 6 to 18 nT. For most of the rest of the day until
just before midnight the spacecraft is found to be in the solar wind whenever
there is data.
NOV. 2:
- IMP-8 crosses into the magnetosheath just before the beginning of the
day as evidenced by the tripling of the magnetic field. The spacecraft is at
(-7.7, 32.1, -15.5) Re in GSM coordinates. This is not an unusual location
of the bow shock. Four more bow shock crossings follow in the next 3
hours as the spacecraft moves further behind the Earth and closer to the
tail. The spacecraft appears to remain in the magnetosheath for the rest
of the day.
NOV. 3:
- IMP-8 appears to enter the geomagnetic tail just before the start of
the day. The magnetic field is directed toward the Earth with a slight
negative y component as expected for the duskside of a flaring magnetotail.
From the size of the tail and its magnetic flux density we estimate there
is about 400 MW in the tail at this time. At 0000 UT the spacecraft is
at (-21.5, 30.5, -7.18) Re GSM. At 0600 the field becomes less tail like
and magnetosheath plasma appears. This plasma is observed until 0100 UT
of November 4, whenever there is telemetry. The velocity is not exceedingly
high, only about 300 km/s. However, the solar wind density must be very high,
since the inner
magnetosheath along the flanks is usually a low density region. At 2315 UT,
a strong density spike appears lasting about 30 min. after this the velocity
climbs to 420 km/s and the proton density is about 25 cm^-3. The magnetic
field is strongly southward in the distant (IMP-8) magnetosheath during the
density spike.
NOV. 4:
- At 0000 UT the spacecraft is at (-31.7, 22.9, 2.6) Re GSM. At about
0400 UT it enters the tail. The field is pointed to the Earth and slightly
toward -y characteristic of the northern lobe at the dusk tail flank. The
estimated magnetic flux in the tail is 630 MW. Thus the southward turning
and the pressure pulse seem to have added flux to the tail. The spacecraft
stays in the northern lobe of the tail for the rest of the interval (at
least to midnight Nov. 5).
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Last Modified: August 8,1995