DATA_SET_DESCRIPTION |
Data Set Overview
=================
The data from the ROSETTA PLASMA CONSORTIUM (RPC) Fluxgate
Magnetometer(MAG)was submitted by Ingo Richter (TM) for the RPCMAG
team. The PI of the team is Karl-Heinz Glassmeier.
Data have been measured during the COMET ESCORT 1 Phase of ROSETTA.
Included are the following sub-phases:
MTP0010 - STP0030 from 2014-11-22T00:00 to 2014-11-25T23:25
MTP0010 - STP0031 from 2014-11-25T23:25 to 2014-12-02T23:25
MTP0010 - STP0032 from 2014-12-02T23:25 to 2014-12-09T23:25
MTP0010 - STP0033 from 2014-12-09T23:25 to 2014-12-16T23:25
MTP0010 - STP0034 from 2014-12-16T23:25 to 2014-12-19T23:25
MTP0011 - STP0035 from 2014-12-19T23:25 to 2014-12-23T23:25
MTP0011 - STP0036 from 2014-12-23T23:25 to 2014-12-30T23:25
MTP0011 - STP0037 from 2014-12-30T23:25 to 2015-01-06T23:25
MTP0011 - STP0038 from 2015-01-06T23:25 to 2015-01-13T23:25
MTP0012 - STP0039 from 2015-01-13T23:25 to 2015-01-20T23:25
MTP0012 - STP0040 from 2015-01-20T23:25 to 2015-01-27T23:25
MTP0012 - STP0041 from 2015-01-27T23:25 to 2015-02-03T23:25
MTP0012 - STP0042 from 2015-02-03T23:25 to 2015-02-10T23:25
MTP0013 - STP0043 from 2015-02-10T23:25 to 2015-02-17T23:25
MTP0013 - STP0044 from 2015-02-17T23:25 to 2015-02-24T23:25
MTP0013 - STP0045 from 2015-02-24T23:25 to 2015-03-03T23:25
MTP0013 - STP0046 from 2015-03-03T23:25 to 2015-03-10T23:25
All magnetic field data are calibrated data. That means the data
represent the 3 components of the magnetic field measured in physical
units (nT). Data are given in instrument coordinates (LEVEL_A),
S/C coordinates (LEVEL_B) or CSEQ coordinates (LEVEL_C).
Calibration has been applied according to the Ground calibration
results which means:
- temperature dependent offset calibration
- temperature dependent sensitivity calibration
- temperature dependent misalignment calibration
Bad vectors have been removed. Any s/c generated noise and s/c
caused residual magnetic fields are not eliminated. The ground
temperature model for the sensor calibration has been improved
(expanded for a wider temperature range down to - 130 deg C) using
long term temperature model obtained from flight data.
The data are sorted by the sensor (OB: outboard sensor, IB: inboard
sensor)and the measurement mode (M1..M6). They can uniquely be
identified by their file names.
Normally the OB is the Primary (Pri) and the IB is the Secondary (Sec)
sensor. However, this order can be toggled by TCs. This feature has
been tested especially during the commissioning phases.
In cases where the PRIMARY and SECONDARY sensor were toggled the
individual data files (OB/IB) will contain data measured with
different sampling rates according to the actual sampling rates of
the PRIMARY and SECONDARY sensors. Refer to the MODE DESCRIPTION
table below. The actual sampling rate is the only indicator
showing which sensor is the primary and which is the secondary
one.
REMARK:
=======
Due to strong magnetic disturbance by the ORBITER
the magnetic field data are influenced by s/c generated
magnetic fields. The source of these disturbance is manifold:
- transient currents flowing on the spacecraft
- Heater pulses
These rectangular disturbances are in the order of 1-2 nTpp,
depending on the heaters and occur with the PWM periods of
the heaters (usually a few seconds up to minutes)
- Thruster related magnetic field disturbances
These signatures are in the order of 3 nTpp and occur during
Wheel off loading (WOL) maneuvres and Orbit correction
maneuvres (OCM). Endurance is usually up to 20 minutes.
Additional spikes occur during OCMs with periods of
625 mHz and amplitudes of 6 nTpp and about 200ms width.
- Reaction wheel (RW) signatures
The four rotating s/c RWs are causing four different
sinusoidal disturbances with usually slowly varying frequencies
in the range of 1-10 Hz with amplitudes of about 3nTpp.
The 'tilted traces' of these signatures can clearly be seen in
the dynamic spectra and can easily be distinguished from
external magnetic field variations.
- Interference by the RPC-LAP instrument
There are times where the LAP instrument can be seen in the
magnetic field spectrum. The disturbance occurs at a constant
frequnecy of either 3.2 Hz or 3.6 Hz with an amplitude of
about 1 nT.
- etc.
Due to the complexity of these circumstances a proper data
cleaning is an ongoing task. Thus the data of the present dataset
still contain the mentioned disturbance signatures.
Therefore, any use of the data for scientific research has to be
done under consideration of these disturbances.
REMARK ON TIMING
================
It turned out that the OB data are shifted against IB data and also
against ROMAP data by 1s. This behavior has not been corrected in the
data. Therefore, for proper comparison in high resolution analyses,
a time shift of 1s should be subtracted from all OB data.
Alternatively OB data can be left as they are and a 1s shift had to
be added to the IB and ROMAP data.
Mode description:
=================
MODE SAMPLE RATE PACKET PERIOD PACKET LENGTH VECTOR RATE
Minimum Mode M1 1/32 Hz 1024 s 32 Pri Vec 0.03125 vec/s
1 Sec Vec 0.000976 vec/s
Normal Mode M2 1 Hz 32 s 32 Pri Vec 1 vec/s
1 Sec Vec 0.03125 vec/s
Burst Mode M3 20 Hz 16 s 320 Pri Vec 20 vec/s
16 Sec Vec 1 vec/s
Medium Mode M4 5 Hz 32 s 160 Pri Vec 5 vec/s
1 Sec Vec 0.03125 vec/s
Low Mode M5 0.25 Hz 128 s 32 Pri Vec 0.25 vec/s
1 Sec Vec 0.007812 vec/s
Test Mode M6 20 Hz 16 s 320 Pri Vec 20 vec/s
1 Sec Vec 0.0625 vec/s
HK Mode 32 s 8 words 0.03125 vec/s
The HK mode contains coarse magnetic field information, measured by
the primary sensor with 16 bit resolution only. These data will not
be calibrated and are not used for any purpose.
FILENAME CONVENTION & Mode Coding
===================================
Due to operational constraints it might happen that the instrument
mode or the primary sensor has to be switched during a specific
observation.
The actual mode and the primary sensor of the instrument can easily
be identified by analyzing the filename of the actual data files. The
complete filename convention is listed in the EAICD, chapter 3.1.4.
The filenames for EDITED and CALIBRATED data are coded as follows:
___.
RPCMAG yymmddThhmm RAW IB M1..M6 LBL
CLA OB TAB
CLB
CLC
Example: RPCMAG040528T1230_RAW_OB_M3.LBL
RPCMAG040528T1230_RAW_OB_M3.TAB
The filenames for Housekeeping data are coded as follows:
_.
RPCMAG yymmddThhmm HK LBL
TAB
Example: RPCMAG040528T1230_HK.LBL
RPCMAG040528T1230_HK.TAB
LEVEL Description, Science Data
===============================
LEVEL_A : Calibrated data in INSTRUMENT coordinates
(Unit Reference frame)
Table content: Time (UTC), Time(OBT),
Magnetic Field (Bx, By, Bz) [nT],
Sensor Temperature [K], Quality Flags
LEVEL_B : Calibrated data in s/c-coordinates
Table content: Time (UTC), Time(OBT),
Magnetic Field (Bx, By, Bz) [nT],
Sensor Temperature [K], Quality Flags
LEVEL_C : Calibrated data in CSEQ-coordinates
Table content: Time (UTC), Time(OBT),
Position (X,Y,Z) [km],
Magnetic Field (Bx, By, Bz) [nT],
Quality Flags
LEVEL Description, Housekeeping Data
=======================================
LEVEL_A : Calibrated Housekeeping data in Physical units
Table Content:
Time (UTC), Time (OBT),
Temperatures (IB,OB) [K],
Stage_IDs (Flag A,Flag B), Filter Config Flag,
Voltages (Mag_Ref (2.5V), Mag_Neg (-5V), Mag_Pos (+5V)) [V],
Magnetic Field (OB-X,OB-Y,OB-Z) [nT] (Instrument coord.),
LEVEL_B : No HK Data
LEVEL_C : No HK Data
Geometry Information - Coordinate System
========================================
The geometry items
SC_SUN_POSITION_VECTOR
SC_TARGET_POSITION_VECTOR
SC_TARGET_VELOCITY_VECTOR
provided in the label of the data product are relative to the
ECLIPJ2000 frame. This reference frame is built up by Ecliptic
Coordinates related to Equinox of Epoch J2000.
Orientation:
X: Pointing from SUN to Vernal Equinox,
Y: perpendicular to X in Ecliptic Plane,
Z: Perpendicular to Ecliptic plane, pointing up
The items
SUB_SPACECRAFT_LATITUDE
SUB_SPACECRAFT_LONGITUDE
are given in the PLANETOCENTRIC coordinate system.
All these geometry parameters are computed at time t=START_TIME.
Distances are given in km, angles in degrees.
Version Information
===================
The first version of RPCMAG datasets being archived for this comet
phase and calibration level was V6.0.
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