Amāvasyā-Pitṛtarpaṇa: Purūravas and the Soma-Based Ancestral Offering (अमावस्या-पितृतर्पण / सोमतर्पण-विधि)
स तदा ह्याहुतेः कालो दर्शस्य तु वषट्क्रिया / एतदृतुमुखं ज्ञेयममा वास्यास्य पर्वणः
sa tadā hyāhuteḥ kālo darśasya tu vaṣaṭkriyā / etadṛtumukhaṃ jñeyamamā vāsyāsya parvaṇaḥ
Then is the proper time for the oblation (āhuti); in the Darśa sacrifice the rite of “vaṣaṭ” is performed. Know this as the gateway of the season—the parvan of Amāvāsyā.