These are the most frequently used words in this book.
aao
above
across
although
amateurs
another
aperture
appear
arcminutes
arcseconds
area
astronomy
binoculars
bright
brighter
caldwell
california
center
chart
close
cluster
cm
color
constellation
dark
diameter
double
dust
easily
even
fact
faint
fainter
few
field
figure
filter
fine
first
galaxy
geographic
globular
hazy
herschel
however
ic
institute
known
large
larger
lies
light
located
look
lovely
magnitude
may
messier
milky
national
nebula
nebulae
need
ngc
nice
object
observe
observers
open
orange
pa
pair
pale
part
planetary
region
roe
say
science
see
seen
sep
set
several
show
sky
small
society
space
star
system
technology
telescope
time
two
variable
view
visible
white
yellow