The traditional AD&#x2F;BC system (aka the CE&#x2F;BCE system) doesn&#x27;t have a year zero. But astronomical year numbering does. (0 = 1 BC, -1 = 2 BC, etc.) Given the astronomical flavour of this discussion, the assumption that BetaCygni was using astronomical year numbering is reasonable.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Astronomical_year_numbering" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Astronomical_year_numbering</a>