Horary astrology is an ancient branch of horoscopic astrology in which an astrologer attempts to answer a question by constructing a horoscope for the exact time at which the question was received and understood by the astrologer.
The answer to the horary question might be a simple yes or no, but is generally more complex with insights into, for example, the motives of the questioners, the motives of others involved in the matter, and the options available to them.
Horary as a system of divination relies on principles and applications of astrological principles sometimes unique to the branch, though coherent in approach with broader astrological claims. The position of and aspects to the moon are of prime importance. The person asking the question, or "querent," is represented by the ruler of the sign the first house cusp falls on in the horoscope. Planetary aspects to the house cusps are considered more important than in other branches of astrology (although it is the planetary rulers of the houses in question that take precedence in analysis). Other key elements used in horary astrology include the lunar nodes, the planetary antiscia, the fixed stars and the Arabic parts.
Typically, a horary chart is read by first assigning the thing asked about, the "quesited," to a particular house in the chart. For instance, asking "Where is my lost dog?" would be represented by the sixth house, as it is the house that governs small animals (traditionally, smaller than a goat). The house cusp of the sixth house will be in a particular sign, for example Libra. Libra is ruled by Venus, so Venus is considered the "significator" of the lost dog. Venus's state in the horoscope will give clues to the animal's wellbeing, and its placement will give indications related to its location.
Any house system preferred by the astrologer may be used, but commonly horary astrologers choose to divide the chart using the Regiomontanus house system as a space-based, quadrant system.
Understanding the correct house for the context of the question is pivotal to the correct interpretation of a horary question. Everything can be assigned to a house and it is to that house, and its ruler, that the assignation of the quesited is derived. Whatever planet is ruling the sign on the cusp of the house is taken to signify the quesited. The context of the horary will often determine the house. For example, if the horary is about matters pertaining to career, the ruler of the 10th House, natural house for careers and jobs, will be indicate the quesited.
A short, non-exhaustive, list of possible associations with houses follows:
In addition, houses may gain extra meaning by way of 'turning the chart'. If you know that the fourth house relates to the father, and that the third house relates to siblings, you can turn the chart to get the father's sibling by taking the third house (siblings) from the fourth house (father), in other words, by counting three houses from the fourth. In this manner the sixth house (third from the fourth), in addition to its natural meaning, may also be used for any brothers and sisters of the father. In a horary question about, for example, your aunt or uncle, it would make sense to turn the chart and use the sixth house if it is your father's brother or sister, or, alternatively, to use the twelfth house (third from tenth) if it is your mother's brother or sister. Turned houses are called derived houses, as opposed to the normal radical houses. If you doubt whether the fourth or the tenth house represents the father, you can ask a horary question: Which house represents the father in horary? Look closely at the moon (co-significator of You), first (You), fourth and tenth house rulers. This will give you an answer that will work for you.
Fundamental to horary astrology is the concept of planetary dignity and reception. Strength is found in two forms, essential and accidental. Essential refers to the quality of a planet at a particular degree of the zodiac and its ability to express its inherent nature. Accidental fortitudes refer to the circumstances in which the planet "finds itself". That is, if the planet is in a traditionally bad house (6th, 8th, or 12th) in the chart, if it is retrograde, aspected by malefic planet (Saturn or Mars), combust, etc., then it is considered an accidental debility and circumstantially hindered.
Reception refers to how each planet in a horary question chart "view" or "receive'" each other, either favourably, unfavourably, or somewhere in between. If Mars is in Taurus, and Venus is in Scorpio, then each of the planets is in the sign the other planet rules. (Venus is ruler of Taurus, Mars of Scorpio.) This is called mutual reception by rulership, and although each planet is in its detriment, it nevertheless receives the other planet favourably. In some horary questions, a thorough understanding of receptions (and the above example skims the surface of this topic) is required to delineate the interplay of how the various significators view each other what sort of attitudesare taking place in the area of the question.
One of the critical features of horary astrology is so called radicality of the chart. It is believed, that astrologer should avoid further judgment if a horary chart does not meet specific criteria. This ancient rule is sometimes criticized by modern horary astrologers. So, for example, John Frawley in his "Horary Textbook" states that the ancient rules of radicality should be ignored, while other astrologers use the modified criteria of radicality.