Agnipurana 162.12

162.12

upākarmaṇi cotsargaṃ svaśākhāśrotriye tathā(2) /
sandhyāgarjitanirghāte bhūkampolkānipātane //

and at the commencement and suspension rites, and likewise [on the death of] a Vedic scholar of one's own branch; / when there is thunder at twilight, a thunderbolt, an earthquake, or the fall of a meteor;