ErgSat/Mepi

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Medium-Energy Particle Experiments - Ion Mass Analyzer (MEP-i)

Members

  • PI
    • Shoichiro Yokota (Osaka University)
  • Deputy-PI
    • Satoshi Kasahara (The University of Tokyo)


Rules of the Road

  • For the general data policy for the ERG satellite, please refer to this webpage.


Specific to MEP-i Data

  • The data user is strongly encouraged to contact the PI in an early stage of his/her work using MEP-i data to discuss data usage and interpretation.
  • Foe details of the instrument, please refer to the following article:
    • Yokota, S., et al. (2017), Medium-energy particle experiments–ion mass analyzer (MEP-i) onboard ERG (Arase), Earth, Planets and Space, 69(1), 172, doi:10.1186/s40623-017-0754-8. (to the article's webpage)

Updates on the Instrument and data

  • 201804??
    • The initial version of Level-2 normal mode data to be released.
  • 20170511
    • The instrument resumed the regular measurement, and the energy range changed to the new one, from ~10 keV/q to ~184 keV/q (-present).
  • 20170422-20170510
    • No scientific data are available due to some operations for the electrostatic analyzer module.
  • 20170324
    • The instrument started its regular observations with the initial measurement energy range of ~5 keV/q to ~110 keV/q (until 20170421, see also above).


Past articles archived here

Instrument Specifications

  • Energy range: <10 to 180 keV/q
  • Energy resolution: 7% (FWHM)
  • Energy steps: 16 steps per scan
  • Mass discrimination: H+, He2+, He+, O2+, O+, O2+
  • Sensor field of view: 360° (azimuth) × 3.5° (elevation)
  • Number of anodes: 16
  • Geometric factor
    • 2.9×10-4 cm2 sr keV/keV/anode (normal channel)
    • 6.0×10-5 cm2 sr keV/keV/anode (narrow channel)
  • Time resolution: ~8s for full 3-D distribution function

Observation Modes

  • Normal mode: collect a 3-D distribution function data usually every ~8s, ~16s, or ~32s.
  • TOF mode: collect a distribution function with reduced angular resolution but highly enhanced mass resolution.

Observation Mode Changes

  • 20170324 (-present)
    • The regular observations started (-present). The normal mode and the TOF mode are being operated alternately (in a time-sharing manner) over each orbit so far.

Also see "Updates on the Instrument and data" above

Calibration Information

To be described in future.

Science Data Products

AA and BB in a data file name represent the major and minor version number, respectively, of the data.

3-D flux data obtained by the normal mode (file name: erg_mepi_l2_3dflux_YYYYMMDD_vAA_BB.cdf)
Name Description Dimension Nominal Time Resolution Data Load Routine for SPEDAS
epoch Time at the middle of spin sector #8 (time) ~8, 16, or 32s erg_load_mepi_nml
epoch_sp Time at the middle of each spin sector (time) ~0.25, 0.5, or 1s erg_load_mepi_nml
FIDU_Angle_sga Looking directions of detectors in SGA coordinates 2(elev,azimuth angle) x 16(anode) (constant) erg_load_mepi_nml
FIDU_Angle_gse Looking directions of detectors in GSE coordinates (time) x 2(elev,azimuth angle) x 16(anode) x 16(spin phase) ~8, 16, or 32s erg_load_mepi_nml
Quality_flag Quality flag for each anode and spin phase 1byte x (time) x 16(spin phase) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
spin_phase Spin phase number (time) ~0.25, 0.5, or 1s erg_load_mepi_nml
mode_reduction flag for reduction of data accumulation 2byte x (time) ~8, 16, or 32s erg_load_mepi_nml
FPDU Unidirectional differential proton number flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FPEDU Unidirectional differential proton energy flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
count_raw_P Raw proton count (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FPDU_Energy Central (log-averaged) energy of energy bin for protons 16(energy) (constant) erg_load_mepi_nml
FHE2DU Unidirectional differential He++ number flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FHE2EDU Unidirectional differential He++ energy flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
count_raw_HE2 Raw He++ count (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FHE2DU_Energy Central (log-averaged) energy of energy bin for He++ ions 16(energy) (constant) erg_load_mepi_nml
FHEDU Unidirectional differential He+ number flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FHEEDU Unidirectional differential He+ energy flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
count_raw_HE Raw He+ count (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FHEDU_Energy Central (log-averaged) energy of energy bin for He+ ions 16(energy) (constant) erg_load_mepi_nml
FOPPDU Unidirectional differential O++ number flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FOPPEDU Unidirectional differential O++ energy flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
count_raw_OPP Raw O++ count (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FOPPDU_Energy Central (log-averaged) energy of energy bin for O++ ions 16(energy) (constant) erg_load_mepi_nml
FODU Unidirectional differential O+ number flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FOEDU Unidirectional differential O+ energy flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
count_raw_O Raw O+ count (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FODU_Energy Central (log-averaged) energy of energy bin for O+ ions 16(energy) (constant) erg_load_mepi_nml
FO2PDU Unidirectional differential O2+ number flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FO2PEDU Unidirectional differential O2+ energy flux (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
count_raw_O2P Raw O2+ count (time) x 16(spin phase) x 16(energy) x 16(anode) ~8, 16, or 32s erg_load_mepi_nml
FO2PDU_Energy Central (log-averaged) energy of energy bin for O2+ molecular ions 16(energy) (constant) erg_load_mepi_nml
Omni-directional flux data obtained by the normal mode (file name: erg_mepi_l2_omniflux_YYYYMMDD_vAA_BB.cdf)
Name Description Dimension Nominal Time Resolution Data Load Routine for SPEDAS
epoch Time at the middle of spin sector #8 (time) ~8, 16, or 32s erg_load_mepi_nml
FIDO_Energy Central (log-averaged) energy of energy bin common to all ion data 16(energy) (constant) erg_load_mepi_nml
FPDO Omni-directional differential proton number flux (time) x 16(energy) ~8, 16, or 32s erg_load_mepi_nml
FHE2DO Omni-directional differential He++ number flux (time) x 16(energy) ~8, 16, or 32s erg_load_mepi_nml
FHEDO Omni-directional differential He+ number flux (time) x 16(energy) ~8, 16, or 32s erg_load_mepi_nml
FOPPDO Omni-directional differential O++ number flux (time) x 16(energy) ~8, 16, or 32s erg_load_mepi_nml
FODO Omni-directional differential O+ number flux (time) x 16(energy) ~8, 16, or 32s erg_load_mepi_nml
FO2PDO Omni-directional differential O2+ number flux (time) x 16(energy) ~8, 16, or 32s erg_load_mepi_nml
Level-3 Data
Name Description Dimension Nominal Time Resolution Data Load Routine for SPEDAS

Data Inventory (Data Archive Status)

Data repository: http://ergsc.isee.nagoya-u.ac.jp/data/ergsc/satellite/erg/mepi/

Name Processed until Latest Calibration Version Remarks