Home Discussion Forum How do I fix the right ascension marker on my telescope?

How do I fix the right ascension marker on my telescope?

It spins freely on the telescope and I’m assuming that’s a bad thng, though I could be wrong. I need to know how best to align it, if that is necessary. Then I plan to just superglue the damn thing unless I can find a better way.
Thanks in advance.
Thank you, GeoffG. That’s what I needed to know. Can you suggest an appropriate star to use in the northern hemisphere? Perhaps just Polaris?


  1. If I understand your question correctly, it’s just the little “gauge” that has the RA markings on it that’s spinning loosely, but the scope itself is functional (I could verify better if you could update with exactly what model of telescope it is)?
    If that’s the case, don’t worry about it. Most of those RA gauges are just there to make it look “scientific-y” and aren’t accurate enough to really use anyways, and even if it was functional, you can still navigate the sky easily enough by other means… be it star hopping, or COL if the scope provides it, etc. If the scope itself still traverses smoothly, it’s not really a big deal.

  2. It’s supposed to move smoothly, but stay in place once you let go. The idea is to point your telescope at a star of known right ascension and turn the setting circle until it reads the correct right ascension. Then you can set the telescope to point at a different object by moving the telescope until it reads the object’s right ascension. You don’t have to do this with declination because the declination of an object doesn’t change over time.
    Although the above is possible in theory, it usually doesn’t work in practice because the setting circles are too small to read accurately and the mount usually isn’t polar aligned accurately enough. That’s why most amateur astronomers find objects by starhopping rather than using setting circles.

  3. Polaris is the worst star to use, as it is so close to the North Celestial Pole (where earth’s axis points into space), about 1-1/2 full moons away.
    You should use stars that are high and in view in the season and night you are aligning the telescope. That would be for June–the star Arcturus in the early evening. It is at 14h 15.6m RA.
    But GeoffG is right. If you don’t align the polar axle of the mount to the NCP, and you have no motor to follow the stars steadily, as well as drive the RA dial, this is not very helpful. If you align, but with no motor, you will have to move the RA or polar axle motion by the slow motion control or by hand bumping it along to the west yourself. The RA dial has to be reset by hand to match the object you are viewing presently before going on to the next object by using the RA reading.

  4. To answer GeoffG and your additional detail, there are lots. We (astronomers) use constellations close to the object we want and the linear paths of stars. Its like those things poeple taught in school (the two end stars of the big dipper’s bucket point to polaris, etc…). In fact, there are lots of paths from the big dipper that lead to stars (http://www.theskytonight.com/north.jpg)
    However, since you probably don’t know many linear paths of stars, you might as well use the constellations to help your way around. Happy sightseeing!


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