In astrology, the cornerstone of prediction lies in the creation of an accurate astrological chart, commonly known as a horoscope. Precision in delineating this chart is paramount to avoid inaccurate interpretations. While computer-generated horoscopes are readily available, they are often prone to errors, making manual casting a valuable skill.
To accurately cast a horoscope, three essential pieces of information are needed: the time of birth, date of birth, and place of birth. If the exact time of birth is uncertain, a skilled astrologer can perform a rectification process. This involves analyzing significant past events and their timings to make necessary corrections to the birth time. Discrepancies in dates may also arise, particularly when births occurred at night. Historically, in India, a weekday spanned from one sunrise to the next. Furthermore, awareness of historical time adjustments, such as daylight saving time during war years, and the use of the Vikram era for dates is crucial for accurate horoscope construction.
Essential tools for manual horoscope casting include a standard ephemeris and Raphael’s “Tables of Houses.” Using these resources, planetary longitudes are calculated for the specific birth time and date using the rule of three. For Rahu (Caput), the mean longitude is used. Ketu (Cauda), the other shadow planet, is positioned diagonally opposite Rahu. These are considered Karmic planets, and the Rahu-Ketu axis holds significant importance in astrological analysis. It is important to note any retrograde planets, as their placement can significantly influence the chart’s interpretation. The ‘ayanamsa,’ or precession, should also be carefully considered. If the ephemeris is based on the Sidereal or Nirayana system, no ayanamsa deduction is necessary. Next, determine the longitude and latitude of the birthplace. Convert the given time to local time if it is in standard time. Calculate the sidereal time of birth and adjust for the longitude, noting whether it is east or west. Use this information with Raphael’s tables to identify the cusp of the rising sign (ascendant). Apply the rule of three again to precisely calculate the cusp. The tables also provide cusps for the 10th, 11th, and 12th houses. In the Equal House system, the ascendant and 10th house cusps are sufficient. Because the tables use the Sayana or Tropical system, deduct the ayanamsa to obtain the Nirayana or Sidereal cusps.
Once the basic chart is complete, calculate the balance of ‘dasa’ at birth using the moon’s longitude. The commonly used system is the “Vimshottari,” a 120-year cycle. ‘Dasa’ refers to one’s state of being or prevailing life conditions. Indian astrologers use this to analyze the ups and downs indicated in the birth chart. While Western astrology utilizes directional techniques, Indian astrologers also incorporate ‘Gochara,’ or the current planetary positions. Furthermore, ‘gochara’ is often combined with ‘Ashtakavarga’ (eight sections). Additional calculations include ‘vargas,’ ‘balas,’ and ‘arudha,’ among others.