The Vaiṣṇava Calendar is calculated every year before the new Vedic year by His Divine Grace Mahāmaṇḍaleshwar Mahant Śrī Kṛṣṇa Balarām Swāmī Prabhupāda, who appeared in and was raised by an enlightened Gaudiya-Brahmana family, descending from Kasyapa Muni, in the holiest land in India, Sri Vrindaban Dhama. He is expert in Vedic knowledge and holy astrology. He annually calculates the Vaisnava Calendar telling the proper Holy dates and Ekadasi dates. This calendar is calculated with exact agreement with the ancient scripture Haribhakti Vilasa of Srila Sanatana Goswami, a direct disciple of Lord Chaitanya Mahaprabhu.
It is incumbent upon every follower of Bhāgavat Dharma Samāj to abide by this properly astrologically calculated calendar following the exact system of the Haribhakti Vilasa. There are two systems of Vedic astrology — Solar calculation and Lunar calculation. The Vaiṣṇava, devotional lineage, follows the Lunar calendar to calculate the exact Tithi (the lunar day). There are twenty-seven constellations and they travel with the moon. As the moon travels, the Tithi is carried by the moon. Therefore, the Vedic calculation of religious dates works per the position of the moon, and not according to the geographical position of a particular country. In spiritual life, knowing the proper calculation of the Tithi is more important than observing it.
THE VEDIC RULES FOR OBSERVING
EKADASI FAST ON THE DVADASI DAY
In our Vaisnava calendar we carefully follow all the required Vedic rules for calculating the Ekadasi Fasting dates so that the Ekadasi observer receives proper and sufficient merits from the fast.
- If Punarvasu Naksatra falls on the Dvadasi day of bright fortnight (waxing moon), then this Fast is called Jaya Mahadvadasi.
- If Sravana Naksatra falls on the Dvadasi day of bright part (waxing moon), then Ekadasi fast is performed on the Dvadasi day and it is called Vijaya Mahadvadasi.
- If Rohini Naksatra falls on the Dvadasi day of bright part (waxing moon), then Ekadasi fast is done on the Dvadasi day and it is known as Jayanti Mahadvadasi.
- If Puksa Naksatra falls on the Dvadasi day of the bright part (waxing moon), then Ekadasi fast is done on the Dvadasi day instead of on the Ekadasi day, and it is named Papanasini Mahadvadasi day.
- If Ekadasi remains at the day break on the Dvadasi day, then it is called Unmilini Mahadvadasi day, and the Ekadasi fast is performed on the Dvadasi day.
- If ninety minutes before sunrise Ekadasi remains and Dvadasi remains the whole day and mixes with Trayodasi on the next morning, then fasting is done on Dvadasi day and it is called Vyanjuli Mahadvadasi fast.
- On any bright part of a month (waxing moon), if Ekadasi tithi is in the very early morning and Trayodasi remains the whole day till the end of that night, and Dvadasi tithi may or may not be seen (even a fraction of Dvadasi), it is called Trisprusha Mahadvadasi, and the Ekadasi fast is performed on the Dvadasi day.
- If Amavasya (new moon) or Purnima (full moon) tithis extend till the next day, then Fasting for Ekadasi is performed on the Dvadasi day in that fortnight.
Hari Bhakti Vilasa/Bhramanda Purana, sourced by His Divine Grace Mahāmaṇḍaleshwar Mahant Śrī Kṛṣṇa Balarām Swāmī Prabhupāda.