 inter gravissimas was a papal bull issued by pope gregory xiii on february 24, 1582.inter gravissimas bill spencer's  translation of the inter gravissimas, 1999, revised 2002, based on rodolphe audette's transcription of the  text. also includes rodolphe audette's translation into . inter gravissimas prepared for iso tc 154    the document, written in latin, reformed the julian calendar. the reform came to be regarded as a new calendar in its own right and came to be called the gregorian calendar, which is used in most countries today. ==description== the intention expressed by the text of this bull was "to restore" the calendar so that seasonal events critical for the calculation of easter dates would be back in their "proper places" and would be prevented from being moved away again. the idea of reform as such is not otherwise mentioned. the bull identifies "three necessary" things for the correct determination of easter dates: correct placement of the northern vernal equinox; correct identification of the "14th day of the moon" (effectively full moon) that happens on or next after the vernal equinox, and the first sunday that follows that full moon. the first two items were the ones that received attention; the third, about choosing the next following sunday, was not identified as causing any problem, and was not further mentioned. by "restore", gregory meant two things. first, he adjusted the calendar so that the vernal equinox was near march 21, where it had been during the council of nicaea (may 20 â august 25, 325). this required removing ten days of drift. second, he made the tabular 14th day of the moon correspond with the real full moon, removing "four days and more" of drift. this would restore the dates of easter to near where they were at the time of the council of nicaea, although that council had not specified where in the calendar the vernal equinox should fall, and had not adopted any particular type of lunar tables. the practices of the roman catholic church that had become traditional by 1582 for calculating the easter and lunar calendars became settled when dionysius exiguus translated the rules of the church of alexandria from greek into latin in 525. (britain adopted them at the council of whitby in 664 and france adopted them about 775. before these years, france and rome used the tables of victorius of aquitaine, which were published in 457. britain before 664 and rome before 457 used an 84-year pa
1582 16th-century_papal_bulls Documents_of_Pope_Gregory_XIII Gregorian_calendar Specific_calendars