Both the RA and Dec setting circles are equipped with verniers. With
care, the practiced observer can set the telescope to 10
in RA and
and 5' in declination. Examples of how to read the verniers are
given in
Figs. 2 and 3.
Figure 2: The RA vernier is read by obtaining
the hours and minutes from the ``0" mark (16:00 here)
and reading
the number of seconds based upon where the marks on the two
scales line up from the top scale (30 sec in this example).
Thus the telescope is pointing to an RA of
16
00
30
, if the circle was set to the correct
LST at the start of the evening.
Figure 3: The dec vernier is read by
first obtaining the nearest 15 arcmin from
the ``0" mark (
in this example) and
adding the appropriate number of 5' intervals based upon where
the marks line up with the upper scale: 5' here. Thus
the telescope is pointing to 
in this example. For
negative decs the left side of the scale would have
been used.
kessel@noao.edu