Tithi-Nirṇaya for Vratas: Ekādaśī Rules, Saṅkrānti Punya-kāla, Eclipse Observances, and Prāyaścitta
परेद्युर्विबुधश्रेष्टैः कुहूर्ग्राह्या पराह्णगा । मध्याह्नद्वितये व्यात्पा ह्यमावास्या तिथिर्यदि ॥ ३४ ॥
paredyurvibudhaśreṣṭaiḥ kuhūrgrāhyā parāhṇagā | madhyāhnadvitaye vyātpā hyamāvāsyā tithiryadi || 34 ||
அறிவோர் சிறந்தவரே! அமாவாசை திதி இரண்டாம் மதியகாலம் வரை நீள்ந்தால், அபராஹ்ணத்தில் உள்ள குஹூ திதியை முந்தைய நாளிலேயே (பரித்யுஃ) அனுஷ்டிக்க வேண்டும்.
Sanatkumara (in dialogue with Narada)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: adbhuta
It emphasizes dharmic precision: sacred observances should follow correct tithi and time (kāla), because the fruit of a rite is tied to proper calendrical determination.
While technical, it supports bhakti-based vows by teaching when to perform them correctly; accurate timing protects the integrity of devotional observances offered to the deities.
Vedāṅga Jyotiṣa (Vedic calendrics/astronomy): it gives a rule for assigning the Kuhū observance based on Amāvāsyā’s extension across midday (vyāpti) and the parāhṇa criterion.