🪷 महा शिवरात्रि · Mahā Śivarātri

Tradition

Tradition: Shaiva

Vrata: Yes (fasting day)

Primary observance: Strict fast + night-long vigil + 4-yāma pūjā

How the day is decided

Caturdaśī at niśītha: on one day only, that day; on neither, the second; on both, the second (Mādhava, Nirṇayasindhu, Puruṣārthacintāmaṇi and many; the Kaustubha after Hemādri takes the first), except that full on the first and partial on the second gives the first.

Source: Dharmasindhu, Mahāśivarātri-nirṇaya (OCR ~6400-6406); Nirṇayasindhu II. Computed on the Sūrya Siddhānta's sunrise, tithi and Moon at Ujjayinī (a city's page uses that city's sunrise).

Detection Rule (Pure Pañchāṅga-Based)

{
  "tithi_number": 29,
  "tithi_paksha": "Kṛṣṇa",
  "lunar_month": "Phālguna",
  "kala_rule": "maha-shivaratri"
}