Yarp. Her name was Joan Quigley.

2 important excerpts:

Joan herself in her memoir:

Not since the days of the Roman emperors, and never in the history of the United States presidency, has an astrologer played such a significant role in the nation’s affairs of State.

The chief of staff dude who found out and got pissed:

Virtually every major move and decision the Reagans made during my time as White House Chief of Staff was cleared in advance with a woman in San Francisco [Quigley] who drew up horoscopes to make certain that the planets were in a favorable alignment for the enterprise.

There’s a Behind the Bastards episode about it. Highly recommend.