How do I calibrate the right ascension setting circle?
1. Identify a bright star in the sky near the celestial equator (Dec. = 0°) and look up its coordinates in a star atlas. 2. Loosen the R.A. and Dec. lock levers on the equatorial mount, so the telescope optical tube can move freely. 3. Point the telescope at the bright star whose coordinates you know. Lock the R.A. and Dec. lock levers. Center the star in the telescope’s field of view with the slow-motion control cables. 4. Loosen the R.A. setting circle lock thumbscrew (if there is a thubmscrew, some RA circles don’t have a set screw they use friction), this will allow the setting circle to rotate freely. 5. Rotate the setting circle until the arrow under the thumbscrew indicates the R.A. coordinate listed in the star atlas for the object. 6. Do not retighten the thumbscrew when using the R.A. setting circles for finding objects; the thumbscrew is only needed for polar alignment using the polar axis finder scope.
Related Questions
- There is a red circle with a line through it to the right of the name of my phone on the center display screen of MyFord Touch/MyLincoln Touch. What does it mean?
- What is meant by right ascension and declination of a star, how does this differ from altitude and azimuth?
- The Right Ascension (azimuth) setting circle tape moves, what do I do?
