Brihat Jataka
वर्गोत्तमाश्चरगृहादिषु पूर्वमध्यपर्यन्तत: शुभफला नवभागसंज्ञा ॥ सिंहो वृष: प्रथमषष्ठहयाङ्गतौलिकुम्भास्त्रिकोणभवनानि भवन्ति सूर्यात् ॥ १-१४ ॥
If say the planet in a sign occupies the N avamsha of that very sign the planet is said to be "V argottam", (for example if a planet has the longitude 4-16-0 this would mean that he is occupying the Navamsha of Leo in the sign Leo). The planet would be considered as "Vargottam". ln the movable, fixed and mutable signs the lst, 5th and the last Navamsais respectively the "Vargottam" Navamsa. The signs Leo, Taurus, Aries, Virgo, Sagittarius, Libra and Acquarius are respectively the Mool Trikona signs of Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn.
english translation
vargottamAzcaragRhAdiSu pUrvamadhyaparyantata: zubhaphalA navabhAgasaMjJA ॥ siMho vRSa: prathamaSaSThahayAGgataulikumbhAstrikoNabhavanAni bhavanti sUryAt ॥ 1-14 ॥
hk transliteration by Sanscript