🪷 विनायक चतुर्थी · Vināyaka Caturthī (monthly)

Tradition

Tradition: Pan-Hindu

Vrata: Yes (fasting day)

How the day is decided

Caturthī at madhyāhna: on both days, whole or not at all, or in part equally or unequally, the first; touching madhyāhna on the second day only, or in part on the first and whole on the second, the second (the same in every month).

Source: Dharmasindhu, Siddhivināyaka-vrata (OCR 3943-3948: "evaṃ māsāntare ’pi"), caturthī-nirṇaya (1393-1396); 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": 4,
  "tithi_paksha": "Śukla",
  "kala_rule": "ganesha-chaturthi"
}