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How to Use Setting Circles |
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First of all, the setting circles will no get you to the exact object you want, they get you in the general area, most scopes are not precise enough to find the exact spot, there is too much slop in the axes, bearings, etc. But they will get you in the general vacinity of the object. Usually if you use an eyepiece with a wide field of view the object might just be in view.First thing to do before setting up to use your circles is get a list of bright stars in the sky. You will need this to do a preliminary alignment called calibration. Calibrating your telescope is the first step after polar alignmet is done. Setting circles are those little round dials with numbers on them around the two main axe's on your telescope. They both have numbers marked on them. One of the circles has numbers listed from 0 to 90. The other circle has numbers listed from 0 to 24. One set in each direction.Starting at 0 then it has a set of numbers going to the left 1-23 on the top scale and 23-1 on the bottom scale. Then on the main mount you will find an arc of numbers from 0-90. First you will need to know your Latitude before you can set this number. In Phoenix,Az our Lat is 33 o.So you need to set the pointer of this scale to 33 before you begin.This is know as Polar Aligment, Now on to Calibration and Alignment. |
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First of all before you start anything do you see the half moon dial that is blue in color, this dial has Latitude numbers on it, these have to be set before you start anything. If your in the Phoenix,Az area you can set this dial at 33 degrees, use the 33 towards the knob, this points the front of the scope mount towards polaris. In this picture you can see some of the things that I was explaining in other areas of this page. The upper set of numbers on the very top
dial is your DEC numbers this dial goes from 0 to 90 and back to 0 then back to 90 etc. The second set of numbers on the largest dial in the center of the picture is your R.A. or Right Ascension. Notice the upper set of numbers the numbers decrease to the right and the bottom set of numbers increase to the right. So for Northern Hemisphere use the upper set of number on the large dial. The main axis of this mount, thats the one above the blue dial with the large set of numbers on it, the front of this axis needs to point to the north towards polaris. This starts your polar alighment process. |
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Calibration and Alignment |
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Calibration and Alignment are necessary so your scope will be able to take you close to the objects you want. After you have your scope polar aligned,(making sure your scope is aligned with the north star) you are ready to calibrate you setting circles. Get out your list of bright stars, you want to do the calibration with 2 stars as far apart as possible from each other. The further apart the better your alignment will be. OK, lets say your in the evening winter sky. We know where Sirius is and we have the coordinates of 6h 45m R.A. and 16o 43m DEC. (That's 16 degrees). Now point your telescope at Sirius with your tracking running if you have it. Now rotate the right ascension dial until it reads 6h 45m. on the outside set of numbers,or the upper set, the outside is for Northern Hemisphere users and the inside or interior numbers are used if you are in the Southern Hemisphere. Try to get the pointer as close as possible to the reading. Now make sure that the declination of 16 degrees 43m is reading on your DEC dial. The DEC dial does not move you have to rotate the scope in order for these numbers to move, so move your scope to the 16d 43 DEC.Now you have calibrated you scope for Sirius. Now do the same thing on another star as far away from Sirius as possible. After that you scope will be calibrated for the evening. Most of the objects that you want to find by using the R.A. and DEC coordinates will be close to your field of view. Make sure to start with a low power eyepiece so the object will be in the field of view. Once it's centered you then can power up with stronger eyepieces. |
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IIf you have trouble using these directions, you can always join us at Bookmans Telescope Workshops. Check the web-site of www.pasaz.org and look under upcoming events on the left side of the page to see when the next scheduled class is. Or you just might want to bring your telescope to one of our star parties and ask for help there. I would be more than happy to help you out there if you bring your scope with you. That's why we hold star party's to help you out with your equipment. Any question you can also email me at [email protected] |
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