Lychnapsia
... that the birthday of the Egyptian goddess Isis was celebrated officially in the Roman Empire on August 12 at the Lychnapsia, a lamp-lighting festival?
... that the <a href="./Glossary_of_ancient_Roman_religion#dies_natalis" id="mwDo8" rel="mw:WikiLink" title="Glossary of ancient Roman religion">birthday</a> of the <a href="./Ancient_Egyptian_deities" id="mwDpA" rel="mw:WikiLink" title="Ancient Egyptian deities">Egyptian goddess</a> <a href="./Isis" id="mwDpE" rel="mw:WikiLink" title="Isis">Isis</a> was celebrated officially in the <a href="./Roman_Empire" id="mwDpI" rel="mw:WikiLink" title="Roman Empire">Roman Empire</a> on <a href="./Sextilis#Dates" id="mwDpM" rel="mw:WikiLink" title="Sextilis">August 12</a> at the <b id="mwDpQ"><a href="./Lychnapsia" id="mwDpU" rel="mw:WikiLink" title="Lychnapsia">Lychnapsia</a></b>, a <a class="mw-redirect" href="./Ancient_Roman_oil_lamps" id="mwDpY" rel="mw:WikiLink" title="Ancient Roman oil lamps">lamp</a>-lighting <a href="./Roman_festivals" id="mwDpc" rel="mw:WikiLink" title="Roman festivals">festival</a>?