Noumenia celebrates Selene, Hestia, Apollon Noumenios, and the household gods and begins when the first sliver of moon appears in the sky. It is the second of a trio of sacred days marking the boundary between the lunar months. The moonless last night of the preceding lunar month the night before it is sacred to Hecate and that night is Hecate’s Deipnon. The day after the New Moon is Agathos Daimon.
Modern traditions vary. Some groups honor Artemis together with Her brother and in many traditions, Artemis has usurped Selene. Some Hellenic Pagans offer libations to a different Olympian God at each Noumenia celebration.
Many folks take this time to thoroughly clean their homes, or at least their altars, and set intentions for the coming month.