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Old 04-May-2008, 04:31 PM
RickJ RickJ is online now
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Join Date: Dec 2006
Location: Mantrap Lake, MN
Posts: 797
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With an equatorially mounted scope you use Right Angle Sweep to find your object, NOT star hopping. Well you can but that's the hard way. There you need stars to hop from and in a light polluted environment they may be hard to come by.

Right angle sweep doesn't need but one star. Find a star near the object and look up the relationship to the object. Say your chart shows it 4 degrees west and 3.5 degrees north of the star. Put in an eyepiece with a known field of view. I like one of a bit over 1 degree which would be an eyepiece that gives a bit less than 50x with a 50 degree plossl or one that gives a bit under 65 power for an eyepiece with a stated 65 degree field of view.

Center on the star. Note a star at the northern edge of the field of view. Move the scope so it's at the southern edge and note another star near the northern edge. Make this move 3 times then on the forth move just center that star that was at the northern edge of the field of view. Now you do the same going west but for 4 full fields of view and the object is centered in your eyepiece. Once you learn this method is is far faster than the time needed to read this. At first you may have to lock one axis so you don't move on a diagonal but once you get the hang of it its fast and quick. I went through my Herschell 400 with an average seek time of less than 1.5 minutes counting the time at the charts to calculate the move. I would hit 100 objects in three hours using this method. No setting circles needed and the polar alignment need not be all that precise. Being off two or three degrees has little effect on the accuracy. I'd just haul out the 10" f/5 and plop it down. Look to see the polar axis appeared to be pointing north by standing back 10 feet and eyeballing the mount and sky.

If your scope has 6" setting circles or larger you can just use the relative position they show to do the same thing. It doesn't matter that they aren't reading correctly, just that you move accordingly. Here you use RA for east and west not degrees of course. Even though my scope does have circles with the needed accuracy I never use them. To do so means using a red LED light to read them and that just further hurts my dark adaption. Also it takes longer and is less accurate -- at least for me.

Rick
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