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Meade ETX-90EC Astro Telescope Instruction Manual
 Appendix A: TRACKING MOTOR SPEED
WARNING! Never use the Meade ETX-90EC Astro Telescope to look at the Sun! Looking at or near the Sun will cause instant and irreversible damage to your eye. Eye damage is often painless, so there is no warning to the observer that damage has occurred until it is too late. Do not point the telescope or its viewfinder at or near the Sun. Do not look through the telescope or its viewfinder as it is moving. Children should always have adult supervision while observing.
In the polar mode the Electronic Controller normally tracks objects at the sidereal-rate (see Sidereal-rate). For most observing sessions (once the telescope has been polar aligned and the tracking motor activated) there is little need to change this speed.

For objects such as the Moon or a comet that move at slightly different rates, the Electronic Controller arrow keys (1, Fig. 5) are sufficient to move the telescope slightly as the object very slowly moves off-center through the eyepiece field.

To change the tracking rate, for extended observations of an object not moving at the sidereal rate, follow the procedure for the appropriate hemisphere:

Indicator Light Key
The procedures in this manual identify the status of the four indicator lights in a box to the left of the appropriate step. They are depicted as On, Blinking or Off, depending on the mode at that point.

Northern Hemisphere Polar:

1. Press and hold the MODE key (5, Fig. 5) until the Mode function is active (i.e., Lights 1 and 2 are on steady; Lights 3 and 4 signify whatever tracking mode was last chosen).

2. Press the SPEED key (3, Fig. 5) until Lights 1, 2, and 3 are on steady with Light 4 blinking. The telescope is now in the Northern Hemisphere Polar mode.
3. Press the IN key and Light 4 comes on steady. The tracking rate is now 0.5% faster than sidereal. Continue pressing IN until the desired speed is reached.

NOTE: The tracking rate can be increased by up to 65% (127 presses of the IN key).

4. To use a rate slower than sidereal, press the OUT key until Light 4 blinks again (sidereal rate). Press the OUT key again and Light 4 goes out, signifying a tracking rate 0.5% slower than sidereal. Pressing an additional 3 to 4 times will slow the tracking rate to the Lunar rate.

NOTE: The tracking rate can be decreased by up to 65% (127 presses of the OUT key).

5. Press and hold the MODE key until only a single light is on. This exits the Mode function. If northern or southern hemisphere polar mode was chosen, the motor drive starts operating at the sidereal rate.
6. Use the four arrow keys (1, Fig. 5) to slew the telescope to the desired object. To change the slew speed, press the SPEED key.

Southern Hemisphere Polar:
1. Press and hold the MODE key (5, Fig. 5) until the Mode function is active (i.e., Lights 1 and 2 are on steady; Lights 3 and 4 signify the tracking mode last chosen).

2. Press the SPEED key (3, Fig. 5) until Lights 1 and 2 are on steady, Light 3 is off, and Light 4 is blinking.
3. Press the IN key and Light 4 comes on steady. The tracking rate is now 0.5% faster than sidereal. Continue pressing IN until the desired speed is reached.

NOTE: The tracking rate can be increased by up to 65% (127 presses of the IN key).

4. To use a rate slower than sidereal, press the OUT key until Light 4 blinks again (sidereal rate). Press the OUT key again and Light 4 goes out, signifying a tracking rate 0.5% slower than sidereal. Pressing an additional 3 to 4 times will slow the tracking rate to the Lunar rate.

NOTE: The tracking rate can be decreased by up to 65% (127 presses of the OUT key).

5. Press and hold the MODE key until only a single light is on. This exits the Mode function. If northern or southern hemisphere polar mode was chosen, the motor drive starts operating at the sidereal rate.

6. Use the four arrow keys (1, Fig. 5) to slew the telescope to the desired object. To change the slew speed, press the SPEED key.

Appendix B: Helpful Charts

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