Lovell navigated by star sightings using a sextant built into the spacecraft, measuring the angle between a star and the Earth's (or the Moon's) horizon.
lˈʌvɛl nˈævɪɡˌeɪɾᵻd baɪ stˈɑːɹ sˈaɪɾɪŋz jˈuːzɪŋ ɐ sˈɛkstənt bˈɪlt ˌɪntʊ ðə spˈeɪskɹæft, mˈɛʒɚɹɪŋ ðɪ ˈæŋɡəl bᵻtwˌiːn ɐ stˈɑːɹ ænd ðɪ ˈɜːθz ɔːɹ ðə mˈuːnz hɚɹˈaɪzən.