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The following files contain plots of the direction of Saturn's field as seen by Cassini during SOI and during MAG internal field observations in the Saturn tour. The direction of the B-field is represented in RA and Dec coordinates on a projection of the sky. There are two directions marked B(+) (parallel to B-field) and B(-) (anti-parallel). The purple lines (locii) extending from the B-field directions show how these directions change with time during the observation (each plot covers a particular time interval, indicated in its title).
The plots also show the MAG 45 degree fields of view - basically the cone of directions which are situated at 45 degrees from the B-field direction. When appropriate, the Cassini +X axis direction should lie inside one of these fields of view. The MAG fields of view will also change with time, so the plots have been designed to cover 1 hour of time at most - even so, in some cases (especially close to Saturn) the B-field locii may still be large in comparison to the field of view. In such cases, plots of higher time resolution may be required for planning purposes.
The timing data of the MAG internal field observations was obtained from the CIMS database as at December 2002. This may require updating in future.
Also shown are some 'standard' directions used in pointing design:
Accompanying each B-field / FOV plot is a plot showing the trajectory (in Saturn-centred co-ordinates) of Cassini over the same time interval. Latitude, longitude and range are plotted against time.
Check of B-field / +X axis angle for Greg Fletcher's pointing design, as contained in the following C kernels:
The file below contains Giacomo's field modelling analysis for the planned MAG internal field periods from SOI through to the end of year 2006. It will be updated as the C kernels for subsequent portions of the planned tour are produced and analysed.
Giacomo's Internal Field Analysis (June, 2004)
The following files contain plots / text generated using the C Kernels produced by the sequence planning process. Only the MAG internal field periods are shown, since this is the only time that MAG is in the scalar mode, which is sensitive to spacecraft orientation. As a function of time, the quantities shown are: angle between B-Field and +X axis, SPV model field strength, and spacecraft range with respect to Saturn centre.
The red part of the curve shows time intervals where pointing is NOT MAG-compliant (i.e. B-Field/+X angle lies between 60 and 120 degrees). The green part of the curve shows time intervals where pointing IS MAG-compliant, and spacecraft is closer than 4 RS to the planet centre. The blue part of the curve shows time intervals where pointing IS MAG-compliant, and spacecraft is further than 4 RS from the planet centre.
The following files contain plots of the orbits of Cassini and Titan, viewed by an observer looking down on the orbital plane of Saturn. Cassini orbits are coloured red, and Titan orbits are coloured magenta. 'S' marks the position of Saturn at the origin of the plot. Tick marks on the orbits indicate time, and occur approximately every five days. Format for the tick marks is DdddThh:mm , which indicates day of year and UTC hours, minutes.
There are seven plots following the orbit plot. These show, as a function of time, the following quantities:
The following files contain information intended to facilitate the analysis of magnetic data taken during the Cassini flyby of Jupiter (Nov 2000 through Feb 2001), and also the flyby of Phoebe (June 11 2004, however files cover May through July 2004). Orbital data for Titan is also available (currently for June through August 2004).
The transformation matrix elements are currently given for the RTN-->JSO and RTN-->KSO transformations only. The files contain 9 matrix elements. These are the three components of each of the (locally defined) R, T and N vectors, as seen in the JSO and KSO systems. This is intended to allow easy transform of RTN magnetic components into either of these two planet-based systems. For example (see file column headings), a B-Field with RTN components (BR, BT, BN) will have X component in the KSO system of BR*RVEC_X + BT*TVEC_X + BN*NVEC_X.
Note that the KSO and JSO systems used for these calculations are defined so that the XY plane coincides with Jupiter's orbital plane (JSO) and Saturn's orbital plane (KSO).
The following files are trajectory information for Cassini during the period around SOI, and until end of 2004. Some include predictions for the magnetic field based on the SPV model.
Note that the definition of the Titan Interaction coordinates (TIIS) is as follows: The Titan Interaction System (TIIS) is Titan centered, has the +X axis along the direction of corotational flow, +Y towards Saturn's centre and is right-handed. It has been used in Voyager work and theoretical work by members of the MAG team, and also by the UCLA team (Galileo work). TIIS is also used in a number of other theoretical papers. Not too far from Titan, the TIIS components are very close to KRTP except for the sign, i.e. R ~ -y, T ~ -z and P ~ +x, if R, T and P respectively denote radial, meridional (theta) and azimuthal (phi) directions.
Spacecraft trajectory during Enceladus encounters: