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Polar alignment of GOTO mounts

Nick Cox

11/8/2016

 

For those of you with equatorial mounts, such as Skywatcher’s EQ5/6 mounts, accurate polar alignment will mean good tracking either manually or by RA motor drive. It is particularly important with GOTO systems without automatic alignment. I had an email from a friend in the north. Whatever he did , the first target was accurately placed in the eyepiece. Using GOTO, as time passed he lost all targets out if the field of view. I asked him to forward his polar alignment. He sent a diagram of Polaris opposite the etched circle. Apparently he set up like this every session.

Polaris is a degree away from the celestial pole. It's offset towards Kochab and rotates around the celestial pole. Offsetting the mount to get Polaris in the etched circle will give you super tracking. To find the position of Polaris, I recommend that you refer to an tablet device App such as “Polar Align”. Your handset will also come up with Polaris time. Using the mount RA and declination bolts get Polaris at the equivalent time on the etched circle.

You can also keep both eyes open and match the angle of Kochab to Polaris, putting Polaris in the small circle at this angle. This is the Kochab clock method.

Releasing the RA clutch will let you position the tiny circle at the correct position. Load up with the OTA and weights. It's vital to recheck Polaris alignment. Flex on the mount may have pushed this out. Secure your bolts, not over tightly. 

Levelling before alignment should be as accurate as you can get it. I cannot understand frequently given advice just to point the mount north and get it approximately level.

Synscan GOTO divides the sky into 81 sections, if you align it to stars, it will assume you've got accurate tracking by polar alignment to get your next target.

Clear skies !

Nick.

 

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