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PERFORMANCE ENHANCEMENT - POLAR ALIGNMENT POSITION - Part 5
by: Clay Sherrod
This photograph shows my ETX 125 in the proper Home Position for Polar mounting mode. There have been a great number of inquiries lately and some new ETX users (and those new to Polar Mode) are setting up improperly.
At latitude 35 degrees north at my observing locations, note that the telescope tube (seen with the cap on) if aimed at NORTH, in line with the parallel-to-the-ground fork arms. This position is easy to achieve and is the first step for successful:
1) initial alignment (be sure to set AutoStar to "Polar" under "Telescope/Mount";
2) accurate GO TO of all objects for the rest of your observing session; and,
3) long period, high power tracking of celestial objects.
To achieve this position, refer to Part 3 of the "Enhancement Guide..." regarding the setup and relation to the internal "hard stops" of the ETX telescope. To "get to" where this telescope is pointing requires that you adjust your tripod so that the fork arms are pointing north and your latitude (wedge or tripod head tilted) is set so that the fork arms are roughly aimed at the star Polaris as shown. MAKE SURE that the telescope's center of gravity is equally distributed as nearly directly above the center of the tripod as possible to avoid disastrous spills during the dark of night!
In this photo, several items point to perfect Home Position for polar mode scopes:
A - the eyepiece and finder have been rotated CLOCKWISE in the RA axis (azimuth) from the hard stop until they are positioned in the "UP" position as shown; in this photograph the DEC setting circle should read "90" degrees if set properly (the best way to adjust your setting circle is to aim and level with the "lens end" of your scope STRAIGHT UP; when level circle should read - or be adjusted to - your exact latitude. That sets the circle accurately if clamped securely after adjustment).
B - the base control panel should be on the WEST side of the telescope/tripod assembly as shown;
C - the #883 tripod (fine for the ETX 90 but not recommended for the ETX 125 in polar) should have the tripod leg marked "N" aimed north, with the fork arms directly above and equidistant from the center of that leg; the #887 tripod legs for the ETX 125 should be positioned with ONE leg DUE SOUTH, and the other two (as shown here) in a northeast / northwest orientation.
Once in this position, a quick finder centering of Polaris (and offset via the "Kochab's Clock - "Observational Guides/References/Precise Portable Polar Alignment") using only the adjustments in the tripod (not the slow motions of the telescope) will get you very close to good polar alignment for a successful alignment and subsequent night's enjoyment of your ETX telescope in Polar Mode!
Arkansas Sky Observatory
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