Advanced Composition Explorer (ACE) Solar Isotope Spectrometer (SIS) Level 2 Data

The Solar Isotope Spectrometer (SIS) is designed to provide high
resolution measurements of the isotopic composition of energetic
nuclei from He to Ni (Z=2 to 28) over the energy range from ~10 to
~100 MeV/nucleon. During large solar events, when particle fluxes can
increase over quiet-time values by factors of up to 10000, SIS
measures the isotopic composition of the solar corona, while during
solar quiet times SIS measures the isotopes of low-energy Galactic
cosmic rays and the composition of the anomalous cosmic rays which are
thought to originate in the nearby interstellar medium. The solar
energetic particle measurements are useful to further our
understanding of the Sun, while also providing a baseline for
comparison with the Galactic cosmic ray measurements carried out by
CRIS.

SIS has a geometry factor of ~40 cm2--sr, which is significantly
larger than previous satellite solar particle isotope
spectrometers. It is also designed to provide excellent mass
resolution during the extremely high particle flux conditions which
occur during large solar particle events.

SIS 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 energetic charged
particle fluxes over the following time periods:

- 256 seconds
- hourly
- daily
- 27 days (1 Bartels rotation)

Currently, flux data are available for 8 elements, in units of
particles/(cm2 Sr sec MeV/nucleon), in eight energy ranges. The energy
ranges are different for each element. The elements for which data are
available are:

- He, C, N, O, Ne, Mg, Si, S, and Fe.

See:
http://www.srl.caltech.edu/ACE/ASC/level2/sis_l2desc.html