170
Śrīmad-Bhāgavatam
[Canto 7, Ch. 14]
the month of Kārtika, on the four aṣṭakās in the winter season and cool season, on the seventh lunar day of the bright fortnight of the month of Māgha, during the conjunction of Maghā-nakṣatra and the full-moon day, and on the days when the moon is completely full, or not quite completely full, when these days are conjoined with the nakṣatras from which the names of certain months are derived. One should also perform the śrāddha ceremony on the twelfth lunar day when it is in conjunction with any of the nakṣatras named Anurādhā, Śravaṇa, Uttara-phalguni, Uttarāṣāḍhā or Uttara-bhādrapadā. Again, one should perform this ceremony when the eleventh lunar day is in conjunction with either Uttara-phalguni, Uttarāṣāḍhā or Uttara-bhādrapadā. Finally, one should perform this ceremony on days conjoined with one's own birth star [janma-nakṣatra] or with Śravaṇa-nakṣatra.
PURPORT
The word  ayana  means "path" or "going." The six months when the sun moves toward the north are called  uttarāyaṇa , or the northern path, and the six months when it moves south are called  dakṣiṇāyaṇa , or the southern path. These are mentioned in  Bhagavad-gītā  (8.24–25). The first day when the sun begins to move north and enter the zodiacal sign of Capricorn is called Makara-saṅkrānti, and the first day when the sun begins to move south and enter the sign of Cancer is called Karkaṭa-saṅkrānti. On these two days of the year, one should perform the  śrāddha  ceremony.
Viṣuva, or Viṣuva-saṅkrānti, means Meṣa-saṅkrānti, or the day on which the sun enters the sign Aries. Tulā-saṅkrānti is the day on which the sun enters the sign Libra. Both of these days occur only once within a year. The word  yoga  refers to a certain relationship between the sun and moon as they move in the sky. There are twenty-seven different degrees of  yoga , of which the seventeenth is called Vyatipāta. On the day when this occurs, one should perform the  śrāddha  ceremony. A  tithi , or lunar day, consists of the distance between the longitude of the sun and that of the moon. Sometimes a  tithi  is less than twenty-four hours. When it starts after sunrise on a certain day and ends before the sunrise of the following day, the previous  tithi  and the following  tithi  both "touch" the