DATA_SET_DESCRIPTION |
Data set Version 2.0
====================
The Science RIDs from the October 2018 review have been applied
to this ROSINA dataset. Some minor species (CH4, NH3, HCN, H2CO,
C2H6, CH3OH, H2S, C2H5OH, OCS, CS2) detected by DFMS were also
added to the V2.0 of the datasets. As a result, V2.0 of this
CODMAC L5 dataset has been created, using the COPS, DFMS, and
RTOF science data from the CODMAC L2 V2.0 (COPS) and CODMAC L3
V2.0 (DFMS and RTOF) datasets. These changes also affect the
structure of the PDS files: columns with references to the files
used to extract the minor species densities have been added, and
therefore the local density and the statistical uncertainty
values have been changed. The L3 to L5 conversion of the RTOF
data has been slightly improved, leading to more accurate
density values.
Data set Overview
=================
The CODMAC level 5 science data consist in time series (local
density) covering the Prelanding phase for the major species
H2O, and CO2 for RTOF, and of H2O, CO, O2, CO2, CH4, NH3, HCN,
H2CO, C2H6, CH3OH, H2S, C2H5OH, OCS, and CS2 for DFMS.
Rosetta was at distances between 152 and 1501 km from the comet
during this time.
ROSINA was permanently analysing the coma of the comet with DFMS
and COPS sensors and the RTOF sensor part of the time
(instrument performance permitting), except during wheel
offloadings, when the mass spectrometers DFMS and RTOF were in
standby, and during orbit control manoeuvres, when all sensors
were off. Explanations on the data generation of the ROSINA
sensors can be found in the OPERATION_LOGBOOK.ASC.
Parameters
==========
DFMS and RTOF data contain neutral gas data as well as ion data.
The data are raw, uncalibrated data. COPS data contains nude
gauge pressure values of the combined spacecraft and cometary
signal. For calibrated data we refer the user to the level 3
data.
Calibration
===========
The level 5 data products are based on the COPS L2 PDS, DFMS L3
PDS, and RTOF L3 PDS calibrated products.
Processing
==========
The processing of the RTOF and DFMS CODMAC L3 to L5 PDS derived
data is detailed in the ROSINA_PDS_L3_TO_L5.PDF document.
Software
========
No software will be provided.
Media/Format
============
The standard distribution format for the data is an electronic
volume.
Coordinate System
=================
The geometry items SC_SUN_POSITION_VECTOR,
SC_TARGET_POSITION_VECTOR and SC_TARGET_VELOCITY_VECTOR provided
in the label of the data product are relative to the Earth Mean
Equator and Equinox reference frame of J2000.
SUB_SPACECRAFT_LATITUDE, SUB_SPACECRAFT_LONGITUDE are given in
the Cheops reference frame.
The SPACECRAFT_ALTITUDE gives the distance to the spacecraft
from the target center of mass. These parameters are computed at
time t=START_TIME.
Distances are given in km, angles in degrees.
Cheops Reference Frame
======================
Scholten, F., Preusker, F., Jorda, L, and Hviid, S.,
Reference Frames and Mapping Schemes of Comet 67P/C-G,
RO-C-MULTI-5-67P-SHAPE-V1.0:CHEOPS_REF_FRAME_V1,
NASA Planetary Data System and ESA Planetary Science Archive,
2015.
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