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2.3. iEQ75-GT
TM
Ports
Figure 6. Ports on iEQ75-GT
TM
control box
• R.A. and DEC motor: For connecting to R.A. and DEC driver unit
• Power: Power switch
• DC 12V: 12 volts DC power plug (center positive)
• HBX (Hand Box): For connecting to the 8406 Hand Controller
• iOptron port: For connecting to other iOptron accessories, such as an electronic focuser, a laser
pointer, or a planetary dome control
• RS232: Series port for ASCOM control and main board firmware upgrade
• Autoguide: Autoguiding port for ST-4 compatible guiding cameras
• GPS: GPS antenna connection
• Reticle: Power supply for the Polar Scope dark field illumination LED
2.4. Introduction
You have just purchased a telescope mount that is capable of taking you to a new level of
astronomy. No matter which telescope or optical tube assembly (OTA) you select to install on the mount,
the overall performance will be greatly enhanced. In order for you to get the optimum performance from the
mount and OTA combination, you must assemble and adjust the mount correctly. The following
fundamentals of telescope mounts are included to help you understand the big picture before you get into
the specific details of the iEQ75-GT mount.
Telescope mounts are either equatorial mounts or altitude-azimuth (Alt-Az) mounts. Both types of
mounts rotate the OTA around two perpendicular axes to point to a desired object in the night sky. An
equatorial mount has the right ascension (R.A.) axis aligned with the celestial North Pole (CNP), or celestial
South Pole (CSP), to provide rotation matching the celestial sphere rotation around the Earth and the
declination axis (DEC) to provide elevation relative to the celestial equator. Since all celestial objects
appear to rotate around the CNP, the R.A. axis allows the OTA to rotate with the celestial sphere and
provide accurate tracking for visual observations and astrophotography. R.A. is the celestial equivalent of
longitude. Like longitude, R.A. measures an angle that increases toward the East as measured from a zero
reference point on the celestial equator. An Alt-Az mount has a horizontal axis to provide vertical (altitude)
OTA movement from the local horizon and a vertical axis to provide horizontal (azimuth) OTA movement,
similar to compass headings. An Alt-Az mount can provide tracking that is good enough for visual observing