For all Space Physics data in CDAWeb we provide access to extra notes in the data files themselves at Master Notes.
For ISTP we provide access to ISTP Principal Investigator provided explanatory materials related to the Key Parameter (and in some cases, Higher Resolution) data.
For ISTP we also provide limited notes on identified problems and issues. Click here for Notes on ISTP Key Parameters.
For other Space Physics Data we provide links to Web pages maintained by the Investigator Teams. Click here for Other Space Physics Web sites.
See also NSSDC Space Physics Flight Projects for other background information on the sources - spacecraft or ground-based investigations.
The ISTP Key Parameters are preliminary data intended for use as BROWSE data. Users interested in publication-quality versions of these data are encouraged to contact the appropriate Principal Investigator(s) listed with the datasets in CDAWeb or found through the Heliophysics Data Portal
The information below is compiled from files kept centrally at the ISTP CDHF until late 1994 and additional important warnings/information as we receive them.
Browse data for the MAG instrument consists of 16-second, major-frame averages of the measured magnetic field with subsequent analysis yielding 5-minute, 1-hour and 1-day averages consistent with Browse data from other ACE instruments. Instrument offsets, including spacecraft fields, are derived from past weeks of data and necessarily lag behind the most accurate values computed for use in Level-2 analyses. Users of Browse data should be aware that spurious AC signals, such as possible spacecraft or instrument noise, are not detected and are not removed from the Browse analysis. Depending on the accuracy and stability of offsets applied in the above manner, spacecraft spin tones may be evident in the data. MAG data is not guaranteed during spacecraft maneuvers and spacecraft nutation is likely to contribute directional errors following maneuvers.
MAG Browse data is not validated by the experimenters and should not be used except for preliminary examination prior to detailed studies.
Note: The Electron, Proton, and Alpha Monitor (EPAM) is designed to make measurements of ions and electrons over a broad range of energy and intensity. Through five separate solid-state detector telescopes oriented so as to provide nearly full coverage of the unit-sphere, EPAM can uniquely distinguish ions (E > 47 keV) and electrons (E > 38 keV) providing the context for the measurements of the high sensitivity instruments on ACE.
The browse parameters contain spin averaged data coming from two of the five telescopes. The full resolution and angular data is available from the Johns Hopkins University Applied Physics Laboratory. EPAM is also part of the real-time Solar Wind (RTSW) system developed by NASA and NOAA. The instrument provides 24 hour coverage of the space weather environment as measured by ACE. For additional information contact Dennis Haggerty (Dennis.Haggerty@jhuapl.edu) or Rob Gold (Robert.Gold@jhuapl.edu).
SIS Browse data is not validated by the experimenters and should not be used except for preliminary examination prior to detailed studies.
Note: During periods of high solar activity, the livetime for these
browse parameters may not be calculated correctly, resulting in
incorrect flux values.
Two noisy matrix strip in the instrument were turned off on 2000-318. These strips were causing the livetime for these browse parameters to be calculated incorrectly. This is the cause of the apparent large drop in flux on 2000-318.
Integral flux of high-energy solar protons from the T4 and T67 counting rates of the Solar Isotope Spectrometer (SIS). These browse parameters are designed to emulate the SIS proton rates contained in ACE Real Time Solar Wind Data from NOAA.
During solar quiet times, these fluxes are contaminated by background
from particles entering from the sides of the instrument.
During solar minimum (e.g., 1992 to 1998), on days when the Sun is quiet, the 7 to 10 MeV/nuc energy interval is dominated by anomalous cosmic ray (ACR) nitrogen and oxygen, with a small contribution (< 10%) from galactic cosmic rays (GCRs). Anomalous cosmic rays originate from interstellar neutral particles that are swept into the heliosphere, ionized, picked up by the solar wind and carried to the solar wind termination shock, where they are accelerated to energies of ~1 to ~50 MeV/nuc. The flux of these nuclei sometimes varies by as much as a factor of ~2 over the 27 day solar rotation period in response to interplanetary conditions. The ~40 cm2sr geometry factor of SIS allows these variations to be seen clearly. As we move toward solar maximum conditions in 1999 and beyond, the flux of ACRs is expected to decrease by a factor of ~100 or more, as it becomes more difficult for low energy cosmic rays to enter the inner heliosphere.
During large solar energetic particle (SEP) events, the intensity of low energy nuclei in interplanetary space can increase by factor of 10 to 1000 or more, and for days at a time, this energy interval can be dominated by solar energetic particles with C:N:O ~ 0.4:0.15:1. An example of such an event is seen in early November of 1997 (~Day 310). The quiet time intensity measured by this browse parameter should vary from ~10-8 per cm2sr.sec.MeV/nuc at solar maximum to ~10-6 per cm2sr.sec.MeV/nuc at solar minimum. During large solar particles events it could be as high as ~1 per cm2sr.sec.MeV/nuc.
Note that the energy intervals for the most abundant elements C, N,
and O all differ somewhat from the nominal values of 7 to 10 MeV/nuc.
This browse parameter responds mainly to anomalous cosmic rays during solar-minimum quiet times, to galactic cosmic rays during solar maximum quiet times, and to solar particles during large solar energetic particle events (see discussion for the 7 to 10 MeV/nuc CNO browse parameter). The quiet time flux should vary from a few x 10-8 per cm2sr.sec.MeV/nuc at solar maximum to ~10-5 per cm2sr.sec.MeV/nuc at solar minimum. During large solar particles events it could be as high as ~0.1 per cm2sr.sec.MeV/nuc.
Note that the energy intervals for the dominant elements C, N, and O
all differ somewhat from the nominal values of 10 to 15 MeV/nuc, and
that the relative abundance of the contributing elements depend on the
source of the particles, as noted above and in the description of other SIS
During solar quiet times this browse parameter responds mainly to galactic cosmic rays, with an admixture of anomalous cosmic ray Ne (see also discussion of 7 to 10 MeV/nuc CNO browse parameter from SIS). During large solar particle events the intensity can be orders of magnitude greater for periods of days. The quiet time intensity should vary from ~10-8 per cm2sr.sec.MeV/nuc at solar maximum to a few times 10-7 per cm2sr.sec.MeV/nuc at solar minimum. During large solar particle events the intensity could rise to >10-2 per cm2sr.sec.MeV/nuc.
Note that the quoted energy interval of ~9 to 21 MeV/nuc is strictly valid only for Si. For Ne the corresponding interval is ~8 to ~17 MeV/nuc, while for Fe it is ~12 to ~26 MeV/nuc.
For more information on SIS, see The CRIS/SIS Home Page.
SWEPAM Browse data is not validated by the experimenters and should not be used except for preliminary examination prior to detailed studies.
Sampling schemes are in development to accomodate longer time spans.
Key Parameters for the Plasma instrument are computed at MIT using Level Zero data that are staged to the ISTP/CDHF approximately two weeks after being received on Earth. Thus the plasma instrument's Key Parameters lag real time by something greater than 2 weeks, but less than four.
The electron measurements are obtained 21.5 secs after the ion measurements. Epoch is the measurement time appropriate for the ions. The moments are computed after the fluxes are corrected for background and s/c potential. Algorithms for these corrections are relatively unsophisticated, so the moments are suspect during times of high background and/or high spacecraft potential. Because the determined spacecraft potential is not very precise, the magnitude of the low- energy ion flow velocity is probably not accurate, but the flow direction is well determined.
Tperp and Tpara are obtained from diagonalization of the 3-dimensional temperature matrix, with the parallel direction assigned to the eigenvalue which is most different from the other two. The corresponding eigenvector is the symmetry axis of the distribution and should be equivalent to the magnetic field direction. The eigenvalue ratio Tperp/Tmid, which is provided for each species, is a measure of the symmetry of the distribution and should be ~1.0 for a good determination.
Several of the parameters have a fairly high daily dynamic range and for survey purposes are best displayed logarithmically. These parameters are indicated by non-zero 'SCALEMIN' values in this file. A quality flag value of 1 indicates that the values are preliminary and have not been checked in detail.
We provide six fluxes: Low energy Protons: 50 keV to 400 keV High energy Protons: 1.2 MeV to 5 MeV Low energy Electrons: 50 keV to 225 keV High energy Electrons: 315 keV to 1.5 MeV Helium : ~0.9 MeV to ~1.3 Mev Heavy Ions : ~5 MeV to ~15 MeV (includes carbon, nitrogen, and oxygen We also compute two electron temperatures and densities and two proton temperatures and densities. These are based on approximately the same energy ranges as the fluxes given in above and are determined for relativistic Maxwellian distributions.
Status of SOPA Instrument 1989-046: Operating normally as of 01-Feb-1993
Status of SOPA Instrument 1990-095: Loss of all ion data as of July 1992 All three thin, front, D1 detectors have failed, having become intolerably noisy. The net result of this failure is the complete loss of proton, helium, carbon, nitrogen, oxygen and other high Z Key Parameter data from the instrument. Since all three thick, back D2 detectors are still operating normally, the electron measurements remain only insignificantly affected.
Status of SOPA Instrument 1991-080: Operating normally as of 01-Feb-1993 with the following exception. Detector D1 on Telescope 2 is becoming noisy. This affects proton and ion data from that telescope. Bad data is disabled thru software in the ground processing and is NOT averaged into the Key parameter data. Therefore, the parameters given are good but do not cover the same percentage of the sky.
Data is flagged with a data quality flag as follows: +1 Data is Good 0 Data is Suspect -1 Data is Unusable LANL personnel should be contacted before using any data tagged as suspect.
A variety of malfunctions of the spin plane components (He and Hn) of this instrument have occurred since at least September 1992. These data are useful for detecting a variety of disturbances in the space environment, but the actual field values are not to be trusted. The parallel, or spin axis, component (Hp) of the field appears to be unaffected by the spacecraft or instrument difficulties; however, the offset of this component is difficult to calibrate and questionable. Interpretation of the data is also complicated by the fact that the GOES 6 spacecraft orbit has become more inclined to the equatorial plane than is typical of the GOES satellites.
The GOES 7 magnetometer transverse components (He and Hn) failed on May 2, 1993. At this time an offset also appeared in the spin axis component. This offset was removed on May 18, 1993; however as with GOES 6, the absolute value of the spin axis component also has uncertainties.
The GOES E1 and P1 channels were designed to measure the geostationary flux of electrons of energy E > 2 MeV and protons of energy E such that .6 > E > 4.2 MeV. Because of radiation damage to the GOES-6 E1 detector, these data are not included in the data-set. The GOES -7 electron detector also responds to protons of energy E > 80 MeV. Therefore, during solar energetic particle events, the electron data are often compromised to the extent that they may primarily represent the detector response to energetic protons. GOES-7 particle detector data is missing during an eclipse and for approximately the following 4 hours.
Finally, the geomagnetic cutoff at geostationary orbit is of the order of 1 MeV, which is within the energy range of the P1 channel. Therefore, the flux observed during a solar energetic particle event by channel P1 is a composite of trapped protons at the lower channel energies and event protons which reach the satellite from sources outside the magnetosphere.