Declination Setting Circle question

[Jiggy 67]

Hi all,

I have an EQ2 mount and I have an issue which is driving me crazy trying to get my head round so if someone can explain it like I'm a 5yr old I would be gratefull. The dec scal appears to have 4 scales. There are 2 zeros which both count to 90 degrees in both directions and then count down again so in effect there are 4 sets of 0-90 degrees. The question is which one do you use when setting co-ordinates (I know they are not accurate but I want to understand it for when I upgrade) for both above and below the celestial equater. I hope I've explained my quandry well enough and thanks in advance for replies

[Peter Drew]

The Celestial Equator is 0 degrees, from there the scale reads up to 90 degrees which will be at Polaris. Below the 0 degrees is the Southern Hemisphere and will be expressed as minus figures, the South Pole position being minus 90 degrees.

[The Bat]

They are not labelled + and - because this changes, depending on whether your scope is positioned on the east side of the mount or the west. If you are looking east, your scope will be on the west side of the mount, and vice versa. So you use either scale, I seem to remember (long time since I bothered with them), and you work out which way is + and - based on the coordinates of your calibration stars.

Rachel