PEPE CODMAC level 2 data format

(F.Crary, 13 JAN 02)

There will be one file per product, per day. The file shall contain
measurements which begin between 00:00:00 on that day and 00:00:00 on
the following day (SCET). Measurement numbers will be the same for all
data products, i.e. if a measurement of ELC data is missing, the
measurement numbers in the ELC file will skip the appropriate number.

The files will be flat, binary data, with a fixed series of values
repeated as many times as necessary. This format only describes the data
products generated during and around the encounter with P/19 Borrelly.

File names are of the form xxxyyddd.dat where

xxx = elc Electron data

hsk Housekeeping data

ion Ion singles data

log Ion logicals data

mq Ion mass over charge data

tof Ion time of flight data

yy = 01 Year

ddd = Day of year

Electron data are the flux of electrons as a function of energy and
angle.

Housekeeping data are selected housekeeping values of use in analysis of
the PEPE data.

Ion singles are the flux of all ions as a function of energy and angle.
(In terms of instrument operations, these are the number of start counts
in the time of flight system, regardless of the ion\'s time of flight,
or even whether or not a valid stop signal was measured.)

Ion mass over charge data are the flux of selected ions as a function of
energy and angle. The ions are selected on the basis of time of flight
(i.e. composition) For example, the MQ 0 data are the energy/angle
spectra of all proton. The 15 MQ bins have a one-to-one correspondence
to time of flight, but not necessarily to species (e.g. most of the
counts in MQ bin 1 are He^++^, but some protons also fall into the MQ 1
time of flight bin.)

TOF spectra are the flux of ions as a function of time of flight
(related to composition) and summed over all energies and angles.

All integers are unsigned

Electron (elc\*) data format:

  ----------------------------------------------------------------------------
  Name                Type      Length   Description
  ------------------- --------- -------- -------------------------------------
  Measurement number  Integer   16       Measurement number from start of day

  Time                Integer   32       Measurement start time, sec. from
                                         J2000

  Offset time         Integer   16       Seconds from start of measurement

  Energy Step         Integer   16       Energy step number

  Elevation Step      Integer   16       Elevation step number

  Data, Azimuth 1     Integer   16       Counts in azimuth 1

  Data, Azimuth 2     Integer   16       Counts in azimuth 2

  Data, Azimuth 3     Integer   16       Counts in azimuth 3

  Data, Azimuth 4     Integer   16       Counts in azimuth 4
  ----------------------------------------------------------------------------

There are 144 bits per row and 256 rows per measurement

Ion singles (ion\*) data format:

  ----------------------------------------------------------------------------
  Name                Type      Length   Description
  ------------------- --------- -------- -------------------------------------
  Measurement number  Integer   16       Measurement number from start of day

  Time                Integer   32       Measurement start time, sec. from
                                         J2000

  Offset time         Integer   16       Seconds from start of measurement

  Energy Step         Integer   16       Energy step number

  Elevation Step      Integer   16       Elevation step number

  Data, Azimuth 1     Integer   16       Counts in azimuth 1

  Data, Azimuth 2     Integer   16       Counts in azimuth 2

  Data, Azimuth 3     Integer   16       Counts in azimuth 3

  Data, Azimuth 4     Integer   16       Counts in azimuth 4

  Data, Azimuth 5     Integer   16       Counts in azimuth 5

  Data, Azimuth 6     Integer   16       Counts in azimuth 6

  Data, Azimuth 7     Integer   16       Counts in azimuth 7

  Data, Azimuth 8     Integer   16       Counts in azimuth 8
  ----------------------------------------------------------------------------

There are 208 bits per row and 512 rows per measurement

Logicals (LOG) data format:

  ----------------------------------------------------------------------------
  Name                Type      Length   Description
  ------------------- --------- -------- -------------------------------------
  Measurement number  Integer   16       Measurement number from start of day

  Time                Integer   32       Measurement start time, sec. from
                                         J2000

  Offset time         Integer   16       Seconds from start of measurement

  Energy Step         Integer   16       Energy step number

  Elevation Step      Integer   16       Elevation step number

  Data, Coarse starts Integer   16       Start counts in coarse azimuths

  Data, Fine starts   Integer   16       Start counts in fine azimuths

  Data, Stops         Integer   16       Stop counts

  Data, Resets        Integer   16       Resets
  ----------------------------------------------------------------------------

There are 144 bits per row and 128 rows per measurement

Mass over charge (MQ) data format:

  ----------------------------------------------------------------------------
  Name                Type      Length   Description
  ------------------- --------- -------- -------------------------------------
  Measurement number  Integer   16       Measurement number from start of day

  Time                Integer   32       Measurement start time, sec. from
                                         J2000

  Offset time         Integer   16       Seconds from start of measurement

  Energy Step         Integer   16       Energy step number

  Data, M/Q bin 0     Integer   16       Counts in M/Q bin 0

  Data, M/Q bin 1     Integer   16       Counts in M/Q bin 1

  Data, M/Q bin 2     Integer   16       Counts in M/Q bin 2

  Data, M/Q bin 3     Integer   16       Counts in M/Q bin 3

  Data, M/Q bin 4     Integer   16       Counts in M/Q bin 4

  Data, M/Q bin 5     Integer   16       Counts in M/Q bin 5

  Data, M/Q bin 6     Integer   16       Counts in M/Q bin 6

  Data, M/Q bin 7     Integer   16       Counts in M/Q bin 7

  Data, M/Q bin 8     Integer   16       Counts in M/Q bin 8

  Data, M/Q bin 9     Integer   16       Counts in M/Q bin 9

  Data, M/Q bin 10    Integer   16       Counts in M/Q bin 10

  Data, M/Q bin 11    Integer   16       Counts in M/Q bin 11

  Data, M/Q bin 12    Integer   16       Counts in M/Q bin 12

  Data, M/Q bin 13    Integer   16       Counts in M/Q bin 13

  Data, M/Q bin 14    Integer   16       Counts in M/Q bin 14
  ----------------------------------------------------------------------------

There are 312 bits per row and 64 rows per measurement

Time of flight (TOF) data format:

  ----------------------------------------------------------------------------
  Name                Type      Length   Description
  ------------------- --------- -------- -------------------------------------
  Measurement number  Integer   16       Measurement number from start of day

  Time                Integer   32       Measurement start time, sec. from
                                         J2000

  Data, bin 0         Integer   16       Counts in TOF bin 0

  Data, bin 1         Integer   16       Counts in TOF bin 1

  \...                                   

  Data, bin 1023      Integer   16       Counts in TOF bin 1023
  ----------------------------------------------------------------------------

There are 16432 bits per row and one row per measurement

Housekeeping (HSK) data format: (Data files TBS)

  ----------------------------------------------------------------------------
  Name               Type      Length   Description
  ------------------ --------- -------- --------------------------------------
  Measurement number Integer   16       Measurement number from start of day

  Time               Integer   32       Measurement start time, sec. from
                                        J2000

  Time               Integer   32       Measurement start time, SCLK

  Integration time   Integer   16       Integration time per sample, multiples
                                        of 28.62 ms (legal values are 1, 10
                                        and 20)

  SC_IPS             Integer   16       Ion propulsion system thrust level,
                                        \[1/10 mN\]

  SC_RSC_SUM         Integer   16       RSC thruster on time, \[1/16 sec\]

  SC_SUN_AZ          Integer   16       Sun azimuth, s/c coordinates \[deg\]

  SC_SUN_EL          Integer   16       Sun elevation, s/c coordinates \[deg\]

  ION_HIST_MOD       Integer   8        TBS

  ION_HIST_PK        Integer   8        TBS

  ION_HIST_DMD       Integer   8        TBS

  ION_HIST_DPK       Integer   8        TBS
  ----------------------------------------------------------------------------

192 bits/measurement, 1507 measurements in the encounter data set