Srimad Bhagavatam 7.14.2-23

ayane viṣuve kuryād
vyatīpāte dina-kṣaye
candrādityoparāge ca
dvādaśyāṁ śravaṇeṣu ca

tṛtīyāyāṁ śukla-pakṣe
navamyām atha kārtike
catasṛṣv apy aṣṭakāsu
hemante śiśire tathā

māghe ca sita-saptamyāṁ
maghā-rākā-samāgame
rākayā cānumatyā ca
māsarkṣāṇi yutāny api

dvādaśyām anurādhā syāc
chravaṇas tisra uttarāḥ
tisṛṣv ekādaśī vāsu
janmarkṣa-śroṇa-yoga-yuk

TRANSLATION

One should perform the śrāddha ceremony on the Makara-saṅkrānti [the day when the sun begins to move north] or on the Karkaṭa-saṅkrānti [the day when the sun begins to move south]. One should also perform this ceremony on the Meṣa-saṅkrānti day and the Tulā-saṅkrānti day, in the yoga named Vyatīpāta, on that day in which three lunar tithis are conjoined, during an eclipse of either the moon or the sun, on the twelfth lunar day, and in the Śravaṇa-nakṣatra. One should perform this ceremony on the Akṣaya-tṛtīyā day, on the ninth lunar day of the bright fortnight of 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-phalgunī, Uttarāṣāḍhā or Uttara-bhādrapadā. Again, one should perform this ceremony when the eleventh lunar day is in conjunction with either Uttara-phalgunī, 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 dakṣiṇāyana, 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 Vyatīpāta. 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 twenty-four-hour day between the sunrises. This is called tryaha-sparśa, or a day touched by some portion of three tithis.

Śrīla Jīva Gosvāmī has given quotations from many śāstras stating that the śrāddha ceremony of oblations to the forefathers should not be performed on Ekādaśī tithi. When the tithi of the death anniversary falls on the Ekādaśī day, the śrāddha ceremony should be held not on Ekādaśī but on the next day, or dvādaśī. In the Brahma-vaivarta Purāṇa it is said:

ye kurvanti mahīpāla
śrāddhaṁ caikādaśi-dine
trayas te narakaṁ yānti
dātā bhoktā ca prerakaḥ

If one performs the śrāddha ceremony of oblations to the forefathers on the Ekādaśī tithi, then the performer, the forefathers for whom the śrāddha is observed, and the purohita, or the family priest who encourages the ceremony, all go to hell. 

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Interesting Information

• The holy river Ganges descended on Earth from the heavens on this day.
• This is the day when the sage Parshuram, the sixth incarnation of Vishnu, was born.
• Treta Yug, the period of the holy Ramayana, commenced.
• Ved Vyasa initiated the recital of the great Indian epic Mahabharata before lord Ganesha.
• Lord Krishna’s childhood friend Sudama, visited Dwarka to him and offered him a humble gift of poha (rice flakes). Therefore, Vaishnavas (worshippers of lord Vishnu) ast throughout the day and open their fasts with rice.
• Akshaya Tritiya bears many religious specialties. It is the birthday of Lord Parasurama of the Dasa Avatars of Lord Vishnu. It is the starting day of the Treta Yuga after Satya Yuga.Thus, it is considered as the Ugadi thithi for Treta Yuga. It is the day when Sudhama (kuchela) offered aval to Lord Krishna and got a bounty of wealth through the grace of Krishna. The same day, Pandavas received Akshaya pathra (bowl) from Lord Krishna and thus were able to get unlimited food during their exile. The day has the credit of Veda Vyasa starting the great Mahabharata with Lord Vinayak writing it.It is the day Ganges came down upon the earth from heaven. In fact, Akshaya Tritiya is considered very propitious for offering dhanams of goods like umbrella, sandals, hand fans, food etc.

Description

In Sanskrit, the word “Akshaya” (अक्षय) means “imperishable, eternal, the never diminishing” in the sense of “prosperity, hope, joy, success”, while Tritiya means “third”.^[7][5] It is named after the “third lunar day” of the spring month of Vaisakha..^[6] Akshaya Tritiya is the birthday of Parasurama who is the sixth incarnation of Vishnu, and he is revered in Vaishnava temples.^[8] Those who observe it in the honor of Parasurama sometimes refer to the festival as Parasurama Jayanti.^[9] Alternatively, some focus their reverence to Vasudeva avatar of Vishnu.^[6] According to one tradition, Ved Vyasa began reciting the epic Mahabharata to Ganesha on Akshaya Tritiya. That river Ganges descended to earth on this day.^{Akshaya Tritiya}