How to query the astrolabe of Zenith constellation?

There are two straight lines running through the astrolabe, horizontally across the horizon, and the meridian is from top to bottom. The east and west ends (left and right) of the horizon, namely the heads of the first and seventh houses, are called Ascending Point (asc) and Descending Point (des) respectively, and the upper and lower ends of the meridian, namely the heads of the tenth and fourth houses, are called Zenith (mc) and Zenith (ic) respectively.