ACE/ULEIS Release Notes:
The following are cumulative release notes for the ACE Ultra
Low Energy Isotope Spectrometer (ULEIS) Level-2 datasets. As
new datasets are released or old datasets are processed, this
file will be extended. The assessment of data quality, such
as for instrument saturations, represents the best current
knowledge and may be retroactively updated in future releases.
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Time periods of significance to the Level-2 data are as follows:
1) periods of instrument saturation:
1998 120.25 to 1998 122.25
1998 124.00 to 1998 125.00
1998 126.25 to 1998 126.50
1998 238.25 to 1998 239.00
1998 267.75 to 1998 269.25
1999 22.75 to 1999 24.50
1999 49.00 to 1999 49.25
1999 125.50 to 1999 128.00
1999 177.00 to 1999 178.75
1999 265.25 to 1999 265.75
2000 42.75 to 2000 43.50
2000 97.50 to 2000 98.00
2000 160.25 to 2000 160.75
2000 175.50 to 2000 176.00
2000 195.25 to 2000 198.00
2000 261.50 to 2000 262.00
2000 313.75 to 2000 315.50
2001 86.50 to 2001 87.00
2001 90.00 to 2001 90.50
2001 101.25 to 2001 101.75
2001 118.00 to 2001 118.75
2001 268.75 to 2001 270.50
2001 294.50 to 2001 295.00
2) other events:
1998-161 16:50 - 1998-167 16:35 No data due to possible C&DH reset problem.
1998-226 18:12 - 1998-226 19:21 No data due instrument commanding.
1998-227 14:18 - 1998-227 16:55 No data due instrument commanding.
1998-227 16:55 Switch to TOF-2 triggering
1998-317 15:00 - 1998-324 19:10 No data due to Leonid shower protection.
2000-047 13:15 - 2000-049 09:45 No data due to instrument commanding.
2000-108 16:00 - 2000-109 17:00 Instrument calibration mode; no science data
2000-116 15:00 - 2000-118 00:00 Instrument commanding.
2001-282 17:25 - 2001-283 22:10 Instrument commanding.
2001-299 16:20 Automatic aperture door operation commenced
(see entry below for October 26, 2001).
2003-301 10:20 - 2003-302 13:00 Approximate period in which the instrument
had significant dead time due to high count
rates. During this time, the dead time
varied, with a maximum value of about 83%
during the most intense portions of the event.
2017-297 05:58 Instrument inadvertently turned off.
2017-315 00:00 Instrument returned to pre-shutdown operating state
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Aug. 14, 1998:
Switch telescope basic triggering from Start-1/Stop (= TOF1) to Start-2/Stop (= TOF2)
in order to decrease the frequency of periods when the instrument is saturated. Since
Start-2 MCP stack has lower count rate than Start-1 it is less susceptible
to saturation due to high count rates.
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Apr. 3, 2000:
Gain of Start-1 MCP stack decreases to near zero at 09:52; after this time no
useful TOF1 data.
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October 26, 2001:
Automatic door operation commenced on Oct 26 (DOY 299), 2001, and greatly
reduces the incidence of saturation and loss of MCP gain during intense events.
When the door moves to change the size of the entrance aperture of the
instrument, the door location is telemetered in the instrument housekeeping
data. Existing software automatically adjusts the instrument geometry factor
for such periods, and so the ULEIS Level 2 fluxes at the ASC need no correction
for door motion.
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August 21, 2008:
release of new version of uleis intensities, generated with udf_lister
program including all efficiency updates. List of instrument saturations
updated; several additional periods added.
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Nov. 6, 2009:
release of modified uleis intensities for Bartels rotations 2373-2404 to correct
for a decrease in efficiency for H and He. Other species are not affected.
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April 20, 2012:
release of new version of uleis multipanel browse intensity 4-day plots with added indicator
color bar near top of lower panel that shows approximate door position:
100% open: no indication
25% open: blue line
6% open: orange line
1% open: red line
0% open: black line
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Sept. 3, 2014:
release of new version of uleis multipanel browse intensity 4-day plots with added indicator
on top panel where saturation periods in above list are marked in yellow. List of instrument
saturation periods updated.
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Aug 17, 2022:
comparison between intensities measured by uleis and the Solar Orbiter Suprathermal Ion Spectrograph during
the Solar Orbiter near-Earth flyby in November 2021 show that the uleis He (3 and 4) intensities are
too high. The He (3 and 4) efficiency was increased to lower the He fluxes by a factor of 2.3. Other species
are not affected. Data and plots containing He intensities were reprocessed with the new efficiencies
beginning with uleis observations beginning Jan-1-2020 0:0 to overlap with the start of the Solar Orbiter
mission.
A processing error where during some periods time dependence of the H and He intensities was not implemented
has been corrected. Intensity (HDF) 1 hr, 24 hr, and 27 day averages files, and anisotropy and stack energy plots
for H and He were reprocessed. Since the affected time periods were spread through the mission in an
irregular way, it was decided to reprocess all time periods even though some were not affected.
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