Dies atri (Nova Roma)
The Collegium has defined standards for worship on Dies Atri:
- Dies atri are "dark" days in which fire should not be lit and sacrifices should not be offered in altars.
- Temples should not celebrate public worship.
- All religious ceremonies are private but without sacrifices.
- Making journeys, starting new projects, or doing anything risky should be avoided, and certain gods, including Iuppiter and Ianus, may not be named.
- They are always dies fastus (F) or dies comitialis (C), never dies nefastus (N) or dies nefastus publicus (NP).
The dies atri include two special subcategories:
Dies postriduani: These are the days after all the Kalendae, Nonae and Idus of each month. They are, in general terms, dies fasti (F), but they are days of bad omens for beginning private activities, business or journeys. Public worship is explicitly forbidden.
Dies vitiosi: These are specific dates decreed by the Senate, considered unlucky days on which some disaster for Rome had occurred. The only two fixed dies vitiosi are the dies aliensis, on July the 18th, commemorating the defeat on the Allia river and the sack of Rome by the Gauls, and August the 2nd, a. d. IV Nonae Sextiliae, which is the traditional anniversary of the Battle of Cannae. These days must be declared dies atri through a senatusconsultum.