Three sources contributed significantly to this section: the POINTS
ric Interferometry Mission Strawman Science Program, and the Open and Globular Clusters
report from K. Cudworth of Yerkes Observatory. We include these documents as sections 2-4 in
POINTS measures positions of widely separated objects unresolved by its 2 m baseline (~0.24
rad = 50 mas at
m). Due to its extremely low systematic error, POINTS has extensive
potential for realizing fundamental goals in many areas of astrophysics. POINTS can observe
field stars, binaries, the brighter black hole candidates, open and globular cluster stars, the
brighter stars in nearby dwarf spheroidal galaxies, several AGN, and certain types of solar system
objects. Associated with each of these target types is one or more categories of interesting sci
ence, as detailed below.
Table 1 introduces the science classes and their relationships to the target categories. The first
column serves as a key to both Table 2 and the following text. Table 2 summarizes the target
categories, their associated science, and some of their observational properties. The "Science
Class" column indicates relevant area(s) of science to which each target class contributes.
The faint magnitude limit of 18 adopted here assumes a slit in the spectrometer, which blocks sky
background. If astrophysical science objectives are not considered in hardware design choices,
then a slit will not be included and the faint star limit drops to ~14. Table 3 shows the approxi
mate number of available objects at these two magnitudes for the target categories of Table 2.
Although some science would be lost, substantial impact would still be made in most areas dis
cussed in this section.
Historically, despite our best efforts at predicting and quantifying scientific advances, we often
fail to predict the most exciting discoveries that arise from a new observing capability. We
expect that unanticipated yet significant discoveries will result from a successful mission.
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Reasenberg, R.D., et al., 1988, Astron J 96, 1731, "Microarcsecond Optical Astrometry: An Instrument and its
Harvard-Smithsonian Center for Astrophysics