Masik Shivratri in May 2028

In Delhi: Monday, 22 May, with niśītha from 23:57 to 00:38. Nirṇaya-sindhu p. 340; pp. 334⁠–⁠337

The Śivarātri of every dark-fortnight Caturdaśī, the fourteenth tithi before the new moon. The Kālottara, quoted by Hemādri, gives the name Śivarātri to each month’s dark Caturdaśī, so the Nirṇaya-sindhu decides it by the same tests as Maha Shivratri. Nirṇaya-sindhu p. 340

By Maha Shivratri’s pradoṣa and midnight tests. With midnight on both nights, pradoṣa decides; with pradoṣa on both, midnight decides; when each night has one, midnight decides. Hemādri, reported on the same page, takes the day with more of the night, the earlier when equal; his day is shown where it differs. Nirṇaya-sindhu pp. 334⁠–⁠337, 340

Niśītha is the middle of the night: two ghaṭikās around it, in Mādhava’s words, which this page takes as a fifteenth of the night centred on its midpoint. The texts that favour midnight say Śiva appeared then as the liṅga. Nirṇaya-sindhu pp. 334⁠–⁠335

No. Maha Shivratri is the dark Caturdaśī of Phālguna by the pūrṇimānta months, Māgha by the amānta. Masik Shivratri is the dark Caturdaśī of each of the other months, kept by the same tests. Nirṇaya-sindhu pp. 334, 340

Each date is worked out for the city’s own night. The Caturdaśī begins and ends at the same moment everywhere, but whether it covers a city’s midnight or its pradoṣa depends on when night falls there, so cities far apart can keep different days.