If you have a planisphere, observing the ascendant and MC for a certain time and date is very easy. See the instruction below.
- Set the time and date you want.
- Find the intersections of the ecliptic ( the yellow line circle below ) and the horizon ( the edge of the oval window ).
The intersection at the left-hand side is the ascendant, the right-hand side is the descendant.
- Set a ruler vertically on the center of the planisphere (the green line on the diagram below).
- Find the intersections of the ecliptic and the ruler. The intersection in the oval window is MC, the other side ( covered side ) is IC.