1.

use GUI application frameworks

package (such as ZAF from Zinc) to en-

sure platform portability

E.

reduction of observations

1.

2.

F.

individual class design and testing

II.

Science Issues and Projects to Consider

A.

asteroids

1.

masses from orbital interactions

2.

provide ephemerides (services to the

community)

3.

cumulative effects on planetary

motions

i.

Asteroids are the largest source of

"noise" in the orbits of Mars, Earth-

Moon system.

B.

lunar motion

1.

chaotic dynamics

i.

predictions from numerical

models

ii.

comparisons with LLR data

2.

radiation pressure

**[ref]**

3.

resonant interaction between tidal

and GR terms

4.

lunar librations

C.

Nordtvedt

parameter (anomalous gravi-

tational field energy effects -- i.e., a differ-

ence between gravitational and inertial mass

proportional to the gravitational binding en-

ergy of a body)

D.

GR precession

1.

lunar orbit

2.

Earth's spin

E.

bounds on time variation of the gravita-

tional constant

F.

millisecond pulsars

1.

derive Earth orbit

G.

bounds on dark matter in the solar

system?

H.

planetary satellites?

1.

centroiding vs. satellite-derived cen-

ter of mass

I.

other science?

III.

Documentation

A.

code

1.

source documentation model (see

TM96-01)

2.

interface ("user's manual")

B.

algorithms

C.

physics

1.

GR and partial derivatives

D.

parameter estimation and error and corre-

lation analysis

E.

numerical integration design

F.

reduction of observations

1.3. Top Level Structure.

The top level process structure of Newcomb is

shown in Figure 1. Basic operation is as follows.

The observations module is responsible for reading

input astrometric observations and "massaging" them

as necessary. Massaging operations are listed in

Chapter 2. The observations will be of various types

(cf. Figure 30), taken at various observing locations

(cf. Figure 2), including spacecraft.

The integration module is responsible for nu-

merically integrating a sophisticated dynamical

model of the solar system -- including general rela-

tivistic terms, a detailed Earth-Moon system, plane-

tary spin vectors including precession and nutation,

and an unlimited number of asteroids -- to produce

an ephemeris.

The model ephemeris is then compared with the

observations in the O-C section of the parameter

adjustment module to produce a set of residuals. The

parameter estimator uses the partial derivatives of the

model equations with respect to the model parame-

ters (including initial conditions) to solve in a least

squares sense for the most probable set of model pa-

rameter values that minimizes the O-C residuals.

The adjusted model parameters are then fed back into

both the ephemeris generator and the observation

transformation methods. The data are rereduced as

necessary, and a new ephemeris is generated. These

are again combined to produce a new set of residuals.

This process is iterated until the residuals satisfy pre-

determined success criteria.

*Chapter 1: Top-Level Structure*

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