tached to a specific location
(and a specific time) on the
Earth's surface, to a refer-
ence frame that takes into
account the spinning and
wobbling motions of the
Earth. This spinning and
wobbling frame can be
connected via lunar laser
ranging to a frame that en-
compasses the dynamic so-
lar system, with all its com-
plicated planetary and sat-
ellite motions, each body
affecting to various degrees
the motions of every other
body in accordance with
Newton's and Einstein's
theories of motion in gravi-
tational fields. We then try
to join the solar system dy-
namical frame to a Galactic
frame, which takes the
form of standard catalog
frames such as FK5
2
or
HIPPARCOS
3
, which are
stellar catalogs, or the new
ICRF
4
, based on extragalac-
tic objects. The Naval Ob-
servatory has been and con-
tinues to be among the
world's foremost contribu-
tors to and creators of these
MURISON: MODELING PLANETARY MOTIONS
4 of 20
4
For an informative introduction to the International Celestial Reference System (ICRS),
see
http://aa.usno.navy.mil/AA/faq/docs/ICRS_doc.html
. The ICRF catalog and related
information is available at
http://hpiers.obspm.fr/webiers/results/icrf/README.html
.
3
http://astro.estec.esa.nl/Hipparcos/hipparcos.html
2
http://adc.gsfc.nasa.gov/adc-cgi/cat.pl?/catalogs/1/1149A/
Figure 2 -- A reference frame hierarchy, showing the
context in which modeling planetary motions (shaded
boxes) resides.
Galactic
Reference Frame
Solar System
Reference Frame
Earth Reference
Frame
Extragalactic
Reference Frame
Quasars
Local Reference
Frame
Planetary
Ephemerides
Natural Satellite
Positions
Dynamical
Models
Earth Rotation
VLBI
GPS
GPS
HIPPARCOS
FAME
Where am I?
What time is it?
NPOI
- Spacecraft navigation
- Tests of GR
- Celestial mechanics
- Asteroid masses
- Stellar occultations
- Geophysics
- Geodesy
VLBI, optical
Star Catalogs
Planetary
Positions
Figure 3 -- Connections between reference frames.
data types that
connect the frames
observations that
determine the
frame
topographic
frame
geocentric
frame
solar system
dynamical
frame
galactic frame
extragalactic
frame
planets
nat. satellites
stars
radio stars
quasars
VLBI
space astrometry
s/c ranging
transit circle
radar
LLR
VLBI
transit circle
