Celestron Omni CG-4 Telescope Mount Astronomy Basics - Page 7

For example, let's say the R.A. indicator (zero mark on the vernier) is just left of the 5h 40m mark. This would place it between the 5h 40m mark and the 5h 50m mark. If you look down the vernier scale, you will see that the "4" is the only mark to line up with any of the marks on the R.A. setting circle. This means that you are 4 minutes to the left of the 5h and 40m mark or more simply at 5h and 44m. 7h 6h 10 8 6 4 2 0 Vernier Scale Here's how to use the vernier: 1. Look up the coordinates of the object you want to observe. For our example we will use the Ring Nebula (M57) which is at 18h 53m right ascension. 2. Release the R.A. clamp and rotate the telescope until the R.A. indicator is between the 18h 50m mark and the 19h 00m mark on the R.A. setting circle. 3. Lock the R.A. clamp to hold the telescope in place. 4. Move the telescope in R.A. using the slow motion control handle until the three on the vernier scale lines up with one of the marks on the R.A. setting circle. Remember, the R.A. indicator must stay between the 18h 50m mark and the 19h 00m mark on the R.A. setting circle! 5. Look through the telescope and the Ring Nebula should be within the field of view if you are using a low power eyepiece (assuming you have already set the DEC). ©2011 Celestron • All rights reserved. 7