The Natal Chart casted for specific question at that same time or at the time of judgement is known as Horary. It is also known as Prashna Kundali in Vedic astrology. You can ask "Why it is necessary?" Horary is the most accurate part of natal astrology. We know that most of the persons do not have their time of birth and who has they are not sure. One can get the span of time when such event will happen in life with the help of horoscope if he has correct time of birth, but horary tells about the exact time of frutification. KP always suggests horary even one has correct horoscope. In old days it was a very tedious job to cast horary horoscope but now it is a job of seconds.
In Horary the astrologer asks a number less than 250 (0 - 249) to the queriest. This number is related to the start point of Ascedent and remaining Houses are distributed as per Placidus System and rest of the Horary is same as the normal KP Horoscope. Nakshatra has the facility to have a Horary chart just in a click. Horary contains the following :
Data Input Screen
Ruling Planets, Planetary & Cuspal Position, Lagna & Cuspal Chart
Cuspal Subs, Planetary Subs, Moon & Navansha Chart
Cuspal Aspects & Planetary Aspects
Vimshottari Dasha and Antardasha(120 Yrs)
Antardasha and Pratyantar Dasha