NAME
zero - center the telescope coordinates on bright star
SYNOPSIS
zero [nearby] [meridian]
DESCRIPTION
zero points the telescope to a bright star using
the bright command;, takes an image, locates
the brightest star, offsets the telescope to center the star and revises the
telescope offset parameters CRA and CDEC. The star is chosen in the following
manner: if no arguments are present it is assumed that RA, DEC, EPOCH and
EXPTIME are present in the environment. This method is rarely used and may
become obsolete in the future. The meridian option selects a star
brighter than 2.5 near the meridian with and a declination of +20 degrees.
This option is often used at the beginning of the night to calibrate the
telescope encoders. The nearby option selects a star brighter than 5.0
mag with coordinates near to the current telescope coordinates. Both these
options pick stars that are isolate, i.e. the nearest other bright star must
be farther than 1.5 degree
away.
The zero command is incorporated in the
openup and
acquire
commands.
SEE ALSO
bright,
tserver (zero command)