??10° < |Dec1 – Dec2| < 30°??

[Art McConnell]

.....the absolute value of the difference between the two alignment stars’ declination should be between 10 to 30 degrees.
( 10° < |Dec1 – Dec2| < 30°).

Does this mean at least 10 and not more than 30 degrees apart in dec?

Duh

[chrisecurtis]

That's how I'd read it. The "absolute" just deals with the case where the two stars are on different sides of the celestial equator.

Edited November 6, 2024 by chrisecurtis
added reason for "absolute"

[Zermelo]

1 hour ago, Art McConnell said:

.....the absolute value of the difference between the two alignment stars’ declination should be between 10 to 30 degrees.
( 10° < |Dec1 – Dec2| < 30°).

Does this mean at least 10 and not more than 30 degrees apart in dec?

Duh

It means you can do the subtraction in either order, and the sign of the result doesn't matter, just that the absolute value is within that range.

Edited November 6, 2024 by Zermelo

[Art McConnell]

3 hours ago, Zermelo said:

It means you can do the subtraction in either order, and the sign of the result doesn't matter, just that the absolute value is within that range.

Does this mean at least 10 and not more than 30 degrees apart in dec?

[Zermelo]

Yes. I spelled it out because it isn't about the celestial equator, it works the same wherever you are in the sky.

If you have, say, Dec1 = +20°` and Dec2 = -5°, then Dec1 - Dec2 = 20 - - 5 = 25°, and if you do it the other way around you get - 5 - 20 = - 25°, but taking the absolute value gets you back to 25° again.