Comments and Links for Isee Data

Acknowledgements



Links related to Isee1 and Isee2

  1. Isee-1 & Isee2 MAG Team at UCLA
  2. Isee 1 and 2 Mission Archive Info from NASA's NSSDC
  3. Isee 1 Mission Description
  4. Isee 2 Mission Description

Comments about the ISEE 1 dataset

The instrument paper for the ISEE-1 particle instrument is:
          IEEE TRANSACTIONS ON GEOSCIENCE ELECTRONICS, VOL. GE-16, NO. 3,
          JULY 1978, PAGE 270
Here is the abstract from the instrument paper:
We describe the medium energy particles experiment (MEPE) on-board ISEE 1 and 2. The MEPE consists of the WIM instrument on ISEE 1 and the KED instrument on ISEE 2. Both instruments employ solid-state detectors and magnetic analysis to measure the angular, energy, and intensity distributions of protons (ions) above 24 keV and electrons above 20 keV. The WIM instrument also includes a composistion measurement employing delta-E by E and time-of-flight techniques. Three-parameters analysis is performed above 250 keV/nucleon, and single parameter analysis is performed above 125 keV/nucleon for heluim through oxygen. Three-dimensional angular distrubutions are obtained through the use of a scan platform in the WIM instrument and multiple detector heads in the KED instrument. A variety of operational modes are used to optimize data collection from both instruments. Resolutions up to 128 channels in energy, 192 samples of the unit sphere in angle, and 0.095s in time are available.
 
Here is a summary of the ISEE 1 instrument and data:
ISEE 1 contained two particle instruments - the Wide Angle Particle Spectrometer, or WAPS, and the Heavy Ion Telescope, or HIT. Only the WAPS data is available in this dataset. The WAPS detector measures protons (really ions) and electrons separately. Electrons are swept onto separate solid state detectors using permanent magnets which deflect all electrons up to 1.5 MeV. Higher energy electrons are removed from the ion signal using coicidence logic in the ion detector. According to the instrument papaer, "Electrons with energy >1.5 MeV may reach the ion telescope, but these will be eliminated from being counted through the veto signal of detector B5 with almost 100-percent efficiency." Detector B5 is the second solid state detector encountered by the ions, and it is directly behind the first solid state detector.
 
The WAPS detector has a geometry factor of 0.0086 cm*cm*ster .
 
The WAPS is situated on a scan platform, so that as the spacecraft rotates, the detector look direction can be changed from nearly parallel to the spin axis direction to nearly anti-parallel to the spin axis direction. The scan platform moves from its upper position (nearly aligned with the spacecraft spin axis) to its lowest position (nearly aligned with spacecraft anti-spin axis) in 12 steps. The transitions from one position to the next always occur at the start of a spin. The total angle traversed in going from upper to lower positioning is 160 degrees. Since the spacecraft spin rate is about 19.7 spins per minute (3.04 seconds per spin), the sacen from upper to lower takes about 36.5 seconds. Data collection times are linked to the motion of the scan platform, which is linked to the spin rate of the spacecraft.
 
There are 2 modes of operation for the WAPS detector: low bit rate (LBR) and high bit rate (HBR). In HBR, the electrons and ions are divided into 16 energy channels, and the spin is divided into 16 sectors. In LBR, adjacent energy channels are summed to provide 8 energy bands for electrons and ions. For example, the first and second electron channels are added together as are the third and fourth, and so on. The same goes for the ion channels. In LBR, the spin is divided into only 8 sectors.
 
This table shows all the WAPS channels along with their energy ranges and particle types:
Channel NameParticle Low Energy (keV)High Energy (keV)K-Factor
EL0e22.539.022.78
EL1e39.075.020.88
EL2e75.0120.02.17
EL3e120.0180.01.82
EL4e189.0302.01.94
EL5e302.0477.00.601
EL6e477.0756.00.496
EL7e756.01200.00.494
AL0p24.044.517.25
AL1p44.365.317.00
AL2p65.395.511.71
AL3p95.5142.07.61
AL4p142.0210.05.20
AL5p210.0333.02.88
AL6p333.0849.00.686
AL7p849.02081.00.287
EH00e22.530.5109.7
EH01e30.539.068.7
EH02e39.060.027.9
EH03e60.075.018.0
EH04e75.094.511.7
EH05e94.5120.06.88
EH06e120.0150.06.05
EH07e150.0189.09.00
EH08e189.0238.010.7
EH09e238.0302.05.87
EH10e302.0380.03.07
EH11e380.0477.02.01
EH12e477.0602.01.91
EH13e602.0756.02.13
EH14e756.0952.02.24
EH15e952.01200.02.12
AH00p24.034.269.34
AH01p34.244.568.67
AH02p44.354.868.67
AH03p54.865.367.36
AH04p65.378.055.69
AH05p78.095.540.42
AH06p95.5117.332.44
AH07p117.3142.028.64
AH08p142.0169.026.2
AH09p169.0210.017.25
AH10p210.0263.013.35
AH11p263.0333.010.1
AH12p333.0543.03.37
AH13p543.0849.02.31
AH14p849.01318.01.51
AH15p1318.02081.00.927

The K-Factor is one over the energy difference times the geometry factor. The values in the dataset are given as flux, so you do not need to know the geometry factors, but they are included here for completeness.
 
Also, the data does not preserve the sector information. Since we use a mission independent interface, the flux values are reported along with a particle flow direction (which is opposite to the detector look direction). The measurement time reported for a flux value is the sector midpoint, and the anglular particle flow direction reported for the measurement are also midpoints of the angular region covered by the sector. The coordinates used for particle flow directions are GSE.
 
Things to watch for in the dataset:
 

 
B-Field Data:
The MAG data comes from the UCLA site mentioned above. The b-field values were not changed, altough the data was slightly re-formatted and compressed for easier traversal across the net. The underlying time resolution of the b-field data is 4 seconds.

Comments about the ISEE 2 dataset



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Maintainer:
Jon D. Vandegriff
Last modified: Fri Dec 20 10:14:36 Eastern Standard Time 2002