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Gemini G42+ Observatory

Gemini G42+ Observatory

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#1 Neil



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Posted 07 December 2012 - 10:34 AM

Equatorial mounts are the preferred weapon of choice for the majority of amateur and professional astronomers alike. These mounts have their main axis, or Right Ascension axis aligned with the Earth Axis. On the G42 mount pictured, you can see the polar scope and Right Ascension axis are parallel with each other. The amount of adjustment needed to achieve alignment will depend on your locations latitude. Once aligned however, you need only turn the Right Ascension axis to counter the spin of the Earth to track a star, that's the beauty of these systems. This is also the reason that the Right Ascension axis is also known as the Hour Angle. In the Northern Hemisphere, the pole star Polaris is currently in alignment with the Earth axis. 




In the Southern Hemisphere there is no star in alignment with the Earth axis which make it a difficult business to find the correct alignment. Over the years I have had a few different makes of equatorial mounts. Vixen GPDX, EM200 USD3 and the Losmandy G11, the G11 had its Right Ascension worm gear replaced with the high precision version, which is a common modification for these mounts. They are capable mounts but you need to work on them in order to obtain their best perfermance. 


The reason for selecting the G42+ Observatory model is for its high loader carrying capacity of up to 50kg and its +/- 3 arcseconds periodic error. This makes tracking stars, auto-guiding and imaging a lot easier.

The Takahashi EM200 USD3 is a legendary mount, a simple no fuss mount that just does its job perfectly with only +/- 5 arcsecond periodic error. If you look very carefully at the cheaper Synta EQ6 mounts, you will realise exactly where they got their inspiration from. This is the one mount that I bitterly regret selling on, perhaps one day I will own one once again, if so it will be a keeper no matter what! I sold it because at the time I found its 18kg payload too limiting for my imaging needs.