The Nativity story is likely to be to some degree a non-historical fiction, but one that may well have used real astrological data for the purpose of messianic justification after the manner of the publication of the horoscope of Augustus. This paper first looks for the existing explanation of the star that fits best with the textual and visual sources. Bulmer-Thomas's general explanation of how the star's appearance, 'moving forward' and standstill as described by Matthew match well with stages of the synod cycle of Jupiter presents itself as a plausible starting point for further consideration. The paper then addresses gaps in this theory and thus a refined version of the synod cycle theory is achieved, whereby the Epiphany Star seen by the astrologers at the time they visit Mary and see the child on his mother's lap is identified as indicating that they cast and saw the destiny in the horoscope just as Jupiter reached Second Stationary Point in the first decan of Virgo in May 1 BCE, this decan being called the Child on the Lap of his Mother by Teucer of Babylon. Having established that the Nativity story was probably pinned to the stages of Jupiter's synod cycle, the paper then asks about the birth itself. Counting back from this time of the Epiphany in May 1 BCE when the child was 'in his third year', we arrive at Jupiter's First Stationary Point in November 4 BCE as the time of birth, which was when this planet was at its astrological 'exaltation' in the middle zone of Cancer, the ideal timing for a Hellenistic regal horoscope. The visible identifier of Jupiter's exaltation location is the Manger asterism. Luke says that the 'sign' of the birth would be the Manger, and the word he uses for 'sign' is semeion, a divine omen, a word which was also used in Hellenistic astrology to mean an astrologically relevant place in the sky, supporting the idea that the Saviour in the manger praised by the heavenly host was really Jupiter conjunct and exalted by the stars of the Manger asterism. Various elements of further support for this theory are discussed, including exalted Jupiter (mid-Cancer) at Augustus's birth, features of the 'exaltation' by the heavenly host and the 'sky astonished' along with activity at a standstill around a manger at the time of Christ's birth in the Protoevangelium of James.