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attmove
July 1, 2008
Abstract
Create Attitude History File simulating tracking of a moving target
1 Instruments/Modes
This task operates on the Attitude History File so all Instrument/Modes are applicable.
2 Use
pipeline processing no
interactive analysis yes
3 Description
attmove is a utility task for use in the aid of analysis of moving targets (planets, comets etc). It is based
on an algorithm devied by Pedro Rodriguez (prodrigu@xmm.vilspa.esa.es).
In contrast to movecalc, attmove creates a new Attitude History derived from an existing AHF, using
a second input table which denes the track of the object as a function of time.
attmove uses selects an arbitrary reference pointing (currently calculated from the object track) and
recalculates the attitude of the spacecraft (the VIEWRA and VIEWDECL entries in the AHF) according
to the following formula:
V t = V ref + (V t
ahf V t
obj
)
Where V t is the output attitude, V ref is the reference attitude, V t
ahf
is the spacecraft attitude in the
source AHF at time t and V t
ahf
is the coordinates of the target object at time t, corrected for Geocentric
parallax.
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4 Parameters
This section documents the parameters recognized by this task (if any).
Parameter Mand Type Default Constraints
input yes table none
Name of input Attitude History File
output yes table none
Name of output Attitude History File
track yes table none
Name of input Ephmeris File
minstable no real 30.0
Minimum duration of stable pointing to decimate
granularity no real 30.0
Duration of decimated stable pointing bins
withrefatt no boolean no none
User-dened reference attitude
refra no real -999
Right ascension of the user-dened reference attitude [decimal degrees]
refdec no real -999
Declination of the user-dened reference attitude [decimal degrees]
creatediagnostics no boolean no
Create diagnostics le?
diagle no table attmovediag.ds
Diagnostics le to create
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5 Errors
This section documents warnings and errors generated by this task (if any). Note that warnings and
errors can also be generated in the SAS infrastructure libraries, in which case they would not be docu-
mented here. Refer to the index of all errors and warnings available in the HTML version of the SAS
documentation.
invalidArgs (error)
granularity must be smaller than stable periods
6 Input Files
1. Input AHF le
2. Data set dening the position of the moving object as a function of time with the following
minimal column structure:
column name meaning type units
MJD modied Julian Day number real64 d
RA apparent geocentric Right Ascension real32 deg
DEC apparent geocentric Declination real32 deg
DELTA distance to center of earth real32 AU
7 Output Files
1. Output AHF le
8 Algorithm
9 Comments
References
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