| Sensor | Full Name | Measured Species | Measured Quantities | Typical Energy (KeV) | Measurement Technique | ||||||
SWEPAM |
Solar Wind Electron, Proton & Alpha Monitor | H, He, e- | E/Q distributions | 0.26 - 36 (ions) 0.001 - 1.35 (e-) |
E/Q |
The Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) measures the solar wind plasma electron and ion fluxes (rates of particle flow) as functions of direction and energy. These data provide detailed knowledge of the solar wind conditions and internal state every minute. SWEPAM also provides real-time solar wind observations which are continiously telemetered to the ground for space weather purposes.
Electron and ion measurements are made with separate sensors. The ion sensor measures particle energies between about 0.26 and 36 KeV, and the electron sensor's energy range is between 1 and 1350 eV. Both sensors use electrostatic analyzers with fan-shaped fields-of-view. The electrostatic analyzers measure the energy per charge of each particle by bending their flight paths through the system. The fields-of-view are swept across all solar wind directions by the rotation of the spacecraft.
For more information about the SWEPAM instrument, visit the SWEPAM Home Page, at Los Alamos National Labs.
Oct 23, 2012: SWEPAM data status update
The SWEPAM observations,
especially the density measurement, have become increasing sparse over the
past few years as the primary channel electron multiplier (CEM) detectors have
aged. Now, 13 years past the original planned mission lifetime, these Ulysses
spare detectors do not provide adequate gain to make good measurements. In
response, the ACE science team has developed and implemented, starting Oct 23 2012,
an innovative mission operations concept that more frequently repoints the ACE
spacecraft's spin axis further away from the Sun. This allows other, stronger
CEMs that have received significantly less total fluence to measure the solar
wind; this operational improvement should significantly increase the frequency
of good quality SWEPAM observations, back to levels not seen in several years.
Release notes for SWEPAM level 2 data - provided by the SWEPAM instrument team.
All users of SWEPAM data should read these notes.
Time Data
All level 2 data records for all ACE instruments contain timing information
in the same format. The format of the timing information is described
here.
Solar Wind Data
SWEPAM level 2 data is organized into 27-day time periods (Bartels Rotations -
roughly one solar rotation period).
For each Bartels Rotation, the level 2 data contains time averages of
solar wind parameters over the following time periods:
SWEPAM level 2 data consists of the following data items:
In addition, the ACE spacecraft position is provided, in the GSE coordinate system (float32) and in the GSM coordinate system (float32):
Release notes for SWEPAM level 2 data - provided by the SWEPAM instrument team. All users of SWEPAM data should read these notes.
A data value of -9999.9 indicates bad or missing data for the given time period.
Our Email Address: asc@srl.caltech.edu
Last Updated: 13 July, 2006