G'Day Alphamone!
to IIS!
Let's start with the easy one first. Declination is like latitude on the Earth. A positive number is degrees north of the equator and the negative declination is degrees south of the equator. So a celestial body with a declination equal to your latitude will pass directly overhead at some time (once a day
).
Right Ascension (RA) is the celestial equivalent of longitude, but it is usually measured in units of time (hours, minutes and seconds) rather than degrees, arcminutes and arcseconds (but sometimes it can be measured in degrees, etc). For your setting circles, it is probably in hours, minutes and seconds.
24 hours equals 1 day or 360 degrees of rotation of the earth. So 1 hour equals 15 degrees.
You will notice that your RA circle can be moved. You should be able to spin it around the RA axis to show any value of RA that you want.
To use your setting circles, aim your scope at a star that you know the position of. The declination circle should read the correct declination of the star (if you mount is polar aligned accurately). Then you adjust the RA circle until the RA of the star is reading on the RA circle. From then on you should not need to adjust the RA circle, you should be able to use it to find objects or to measure the position of objects you observe - at least for that session anyway
if you have an RA drive to keep the scope in time with the stars
.
If you don't have an RA drive, then it's more fiddly to use the RA circle... you need to adjust the RA circle to a known star immediately before using it to find or measure another object.
I hope this helps. Keep asking questions if it doesn't!
Al.