Brihat Parashara Hora Shastra
परिवेषश्च्युतश्चक्रादिन्द्रचापस्तु दोषदः। वित्र्यंशास्यष्टिभागाध्यश्चापः केतुखगोऽशुभः॥ ६३॥
Deduct Parivesh from 12 Rāśis to arrive at the position of Chap (Indra Dhanus), who is also inauspicious. Add 16 degrees 40 minutes to Chap, which will give Ketu (UpaKetu), who is a malefic.
english translation
pariveSazcyutazcakrAdindracApastu doSadaH। vitryaMzAsyaSTibhAgAdhyazcApaH ketukhago'zubhaH॥ 63॥
hk transliteration by Sanscript