4. what are latitude and longitude declination (dec) on the sky?

The latitude and longitude declination (DEC) are to the sky and are always measured in either north or south directions, like the measurement that is made for latitude. This measurement is made in terms of degrees, arc-minutes, and arc-seconds.

1 degree corresponds to 60 arc-minute, and 1 arc-minute corresponds to 60 arc-seconds. The symbols that are used for arc-minute and arc-second are similar to those that are used for representing feet as well as inches.

This declination (latitude and longitude declination) describes how much high overhead an object subsequently will rise.