ACE/ULEIS Level 3 Data
Ion Spectrograms and Multipanel Plots
Multi-panel Plots
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Each plot contains 4 days of data. The top panel shows hourly average intensities
for 3He, 4He, O and Fe for the energy range 230-320 keV/n.
The 3He is subject to spillover from 4He and should not be
considered significant unless it is larger than approximately 10% of the 4He intensity.
The middle panel shows individual ion masses and arrival times
for ions of energy 0.4-10 MeV/nucleon. This panel can be useful in assessing the
presence or lack of 3He. The bottom panel shows individual ion reciprocal speed (1/v)
and arrival time for ions of mass 10-70 AMU. Slanted lines in the panel show the arrival
time for particles released at the sun and traveling down a 1.2 AU magnetic field line.
The appearance of the middle and bottom panels is affected when the instrument door
position changes; when this happens the intensity of the ion tracks changes noticeably.
Velocity spectrograms
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Each plot contains 4 days of data, showing the arrival time of all ions
from H through Fe. The X-axis is the arrival time in units of day of
year. The y-axis is the ion speed in units of AU/hour (left side) or
MeV/nucleon (right side). 1 AU/hour corresponds to a speed of 4.155 x
107 m/s; 1 MeV/nucleon corresponds to a speed of about 1.38
x 107 m/s. Ions traveling along a typical curved
interplanetary magnetic field line will travel about 1.2 AU between sun
and earth's orbit. For a burst of ions released at the sun, ions with
higher speed will arrive at ACE before those at lower speed, leading to
characteristic curved patterns for some flares (see the plot 1998-228
through 1998-231 for an example of several such events).
1/velocity spectrograms
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Each plot contains 4 days of data, showing the arrival time of all ions
from H through Fe. The X-axis is the arrival time in units of day of
year. The y-axis is the ion speed in units of 1/(AU/hour) (left side)
or 1/(MeV/nucleon) (right side). Ions traveling along a typical curved
interplanetary magnetic field line will travel about 1.2 AU between sun
and earth's orbit. The slanted lines drawn at intervals on the plot
show the time an ion takes to travel 1.2 AU for each speed. For a
burst of ions released at the sun, ions with higher speed will arrive
at ACE before those at lower speed, leading to characteristic straight
lines in this plot format (see the plot 1998-228 through 1998-231 for
an example of several such events).
Breaks in the distributions at 0.16 MeV/nucleon and 0.4 MeV/nucleon are due to instrumental effects.
Stack-Energy Plots
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Each plot contains 32 days of data beginning on the first day of a Bartels solar rotation
and extending several days into the next rotation. Each plot has one or more panels and shows
intensities for a single rate channel (H, 3He, 4He, C, O, Ne through S, and Fe). There are
one or more panels on each plot, each of which has multiple traces for the element at
different energies.
Anisotropy Plots
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Each plot contains 4 days of data, and is intended to show qualitatively the
presence or absence of anisotropies. Since ULEIS scans only a small portion of the
sunward hemispshere (covering a zone centered roughly 60 degrees from the solar
direction) it does not produce comprehensive anisotropy information. For example,
if the interplanetary magnetic field is pointing nearly in the sunward direction, ULEIS
will sample only a small range of pitch angles and cannot detect anisotropies. However,
for other field line orientations a range of pitch angles will be sampled, and if anisotropies
are large, the 8-sectors of the ULEIS intensities can show significant differences. Each
plot shows a single element (H, 3He, 4He, C, O, Ne through S, and Fe) and several
panels. Each panel covers one energy range and plots each of the 8 sectored rates
with different colors. Large differences between sectored rates, if statistically significant,
indicate the presence of anisotropies.
Return to ACE Contributed Data
ULEIS door position
The ULEIS telescope has a movable door in front of the opening aperture that allows adjusting
the aperture area in order to protect against instrument saturation in intense events. The door
has four possible settings: 100% (open); 26%, 6%, and 1% (see the instrument description
Mason et al., Space Sci. Rev., 86, 409-448, 1998). Early in the mission, the door was moved
only by ground command; after October 26, 2001, 16:20 UT, the door was controlled autonomously
by the on-board software. Intensities from ULEIS posted at the ACE Science Center are corrected
for the door position automatically, and so users of the intensity data do not need to take account of the door
position. However, spectrogram plots posted at the ACE Science Center (i.e. velocity_spectrograms,
1/velocity_spectograms, and portions of the multi-panel plots) show individual ion arrivals, and the
counting statistics for these decrease or increase when the door changes position. A list of door ULEIS
door positions shows the times of all door motions during the mission. Each time the door moves there
are two entries in the table, showing the prior aperture setting and then the new setting. For an example
of a period when door motions affect the appearance of a plot, see the multi-panel plot beginning
2003 day 306, or the 1/velocity_spectrogram plot beginning 2003 day 306.
View the door-position data
Last Updated: July 18 2000