The chart produced by this service is centered at the nominal
position of the asteroid at the requested time. A small circle
surrounds the asteroid's position. A dashed line indicates the
one-sigma uncertainty in the asteroid's position and an arrow
represents the one-hour change in position of the asteroid. The
asteroid's name, topocentric position, and magnitude are printed at
the top of the chart. The observatory name and time of observation are
also indicated there. The size of a plotted star/asteroid is an
indication of its magnitude. Refer to the legend to get a rough
magnitude estimate of each object. North is plotted to the top of the
chart and East is plotted to the left.
Very small regions-If the user chooses a very small
field-of-view, it is possible that no stars will be found in the
catalog. This is treated as an error condition. Select a larger
field-of-view and try again.
Very large regions-If the user chooses a very large
field-of-view, it is possible that too many stars will be selected
from the catalog. (The current limit is 10,000.) This is treated as an
error condition. Select a smaller field-of-view and try again. Only
the 100 brightest stars are plotted. For a large field of view, all
the plotted stars will be fairly bright and fairly similar in
magnitude so the chart will have a strange appearance. The alert user
will also notice that some stars are missing from the chart. These
are most likely stars omitted from the star catalog.