An Aquarius Ascendant means Aquarius was on the eastern horizon at birth; with a sign passing every two hours, birth time decides it. In whole-sign houses, where each sign is one house, Aquarius is the first house. The traditional ruler is Saturn, so Saturn is the lord of the Ascendant. Modern astrologers add Uranus, which this block omits because the Hellenistic tradition had none. Saturn also rules Capricorn, which falls in the twelfth house. Aquarius is a masculine, fixed air sign and the Sun's detriment, a concept the tradition names explicitly only late. The Sun, the day-team light, starts from reduced authority in the horizon's sign. Under sect, the tradition's sorting of planets into day and night teams, a day-team planet in a night chart is called sect contrary. Hellenistic astrologers look to Saturn's sign, house and sect condition.
A note on “detriment”: the early Hellenistic texts note a planet opposite its own sign without naming it. The term is defined only in late and medieval sources, and scholars disagree on whether the idea was implicit earlier.