Setting Circles; Observing With The Telescope - Meade 2045 Operating Instructions Manual

NOTE: DO NOT ATTEMPT TO TURN THE R.A. SLOW-MOTION CONTROL KNOB WHEN THE R.A.
LOCK IS IN THE "LOCKED" POSITION. SUCH AN OPERATION WILL CAUSE INTERNAL DAMAGE
TO THE GEARS OF THE R.A. SLOW-MOTION CONTROL. IN ADDITION, DO NOT ATTEMPT TO
TURN THE TELESCOPE MANUALLY ON ITS FORK MOUNT IN R.A. WHEN THE R.A. LOCK IS
"LOCKED," AS SUCH OPERATION WILL CAUSE RAPID WEAR OF THE INTERNAL CLUTCH
SYSTEM.
SETTING CIRCLES
Setting circles included with the Model 2045 permit the location of faint celestial objects not easily found
by direct visual observation. Located on the top surface of the telescope's drive base, the R.A. circle (7),
Fig. 1, is 6" (15cm) in diameter. The Declination circles (see (3), Fig. 1), are located on top of each fork
tine. With the telescope pointed at the North Celestial Pole, the Dec. circle should read 90' (understood
to mean +90*). Objects located below the 0-0 line of the Dec. circle carry minus Declination coordinates.
Each division of the Declination circle represents a 1 * increment. The R.A. circle runs from 0hr to (but not
including) 24hr, and reads in increments of 5min.
Note that the R.A. circle of the Model 2045 is double-indexed: the upper line of numbers (running
clockwise from 0 to 23) should be used by observers in the Earth's Southern Hemisphere (e.g. Australia):
the lower line of numbers (running counterclockwise from 0 to 23) should be used by observers in the
Earth's Northern Hemisphere (e.g. the U.S.A.).
With the telescope aligned to the pole, center an object of known R.A. in the telescopic field. Then turn
the R.A. circle, which can be rotated manually by moderate thumb pressure, until the R.A. coordinate of
the object is correctly indicated by the R.A. pointer. As long as the telescope's motor drive remains "ON,"
the R.A. pointer will then correctly indicate the R.A. of any object at which the telescope is pointed
throughout the duration of the observing session.
To use the circles to locate a particular object, first look up the celestial coordinates (R.A. and Dec.) of the
object in a star atlas. Then bosen the R.A. lock and turn the telescope to read the correct R.A. of the
desired object; lock the R.A. lock onto the object. Next, turn the telescope in Declination to read the
correct Declination of the object. If the procedure has been followed carefully, and if the telescope was
was well-aligned with the pole, the desired object should now be in the telescopic field of a bw-power
eyepiece.
If you do not immediately see the object you are seeking, try searching the adjacent sky area, using the
R.A. and Dec. slow-motion controls to scan the surrounding region. Keep in mind that, with the 25mm
eyepiece, the field of view of the Model 2045 is about 1 '. Because of its much wider field, the 5x24mm
viewfinder may be of signifbant assistance in locating and centering objects, after the setting circles have
been used to locate the approximate position of the object.
Pinpoint application of the setting circles requires that the telescope be precisely aligned with the pole.
Refer to the preceding section on "Precise Polar Alignment" for further details.
OBSERVING WITH THE TELESCOPE
The Meade Model 2045 4" Schmidt-Cassegrain telescope permits an extremely wide array of serbus
observational opportunities. Even in normal city conditions, with all of the related air and light polutbn,
there are many interesting celestial objects to observe. But to be sure, there is no substitute for the clear,
steady dark skies generally found away from urban environments or on mountaintops. Objects prevbusly
viewed only in the city take on added detail, are seen in wider extensbn, or fainter objects become visible
for the first time.
The amateur astronomer is faced with two broadly defined problems when viewing astronombal objects
through the Earth's atmosphere: first is the clarity, or transparency of the air, and second, the
steadiness of the air. This latter characteristb is often referred to as the quality of "seeing." Amateur