Dhuma, Vyatipata, Parivesha, Upaketu, Indrachapa, Kala, Yamaghanta and Gulika — these eight are the Upagrahas (subsidiary planets); Gulika is computed from half of Yama (Saturn).
ravisphuṭāc caturthaṃ tu dhūmaḥ khyāto manīṣibhiḥ | dvādaśād dhūma hīno yo vyatīpātaḥ prakīrtitaḥ ||
Four signs computed forward from the true longitude of the Sun is known as Dhuma; that same Dhuma deducted from twelve signs gives what is declared as Vyatipata.