The Coligny calendar is a bronze plaque with an inscribed calendar, made in Roman Gaul in the 2nd century CE. It lays out a 5-year cycle of a lunisolar calendar, each year with 12 lunar months. An intercalary month is inserted before each 2.5 years. It is the most important piece of evidence enabling the reconstruction of an ancient Celtic calendar.
The calendar was found in 1897 in France, in Coligny, Ain (near Lyon), along with broken pieces of a life-size bronze statue of a nude male holding a spear, likely meant to portray Mars, the Roman god of war.Charles Picard, Le bronze de Coligny, in L. Rosenthal, "Florilège des musées" du Palais des Arts de Lyon, p. 9, Mairie de Lyon, [s.d.] (1920<>1932). Approximately 40% of the original calendar remains in the form of fragments. It was engraved on a bronze tablet, preserved in 73 fragments, that was originally 134.8 cm wide by 78.0 cm high. With the rim attached the plate measured 52 by 32 (2.75 cm to the ). It is written in the Gaulish language with the Latin alphabet, using Roman square capitals and Roman numerals. Based on the style of lettering and the accompanying statue, the bronze plaque likely dates to the end of the second century CE, although copying errors indicate that the calendar itself is much older.Duval, P.M. and Pinault, G., Recueil des inscriptions gauloises, Tome 3: Les Calendriers (Coligny, Villards d'Heria), CNRS, Paris, 1986, pp. 35–37. It is now held at the Gallo-Roman Museum of Lyon-Fourvière.
Eight small fragments of a similar calendar were found at the double-shrine of Villards-d'Héria. It does not have the holes of a peg calendar that the Coligny calendar does, but otherwise has the same notations. It is now held in the at Lons-le-Saunier.
List of months The names of the twelve lunar year months are reconstructed as , , , , , , , , , , , and . The names occur in the genitive form SAMONI, DVMANNI, RIVRI, etc. in the internal notations of the calendar. The name of the first intercalary month may be listed at the end of the month as QVIMON, possibly for Quimonios, the second is reconstructed as ...antaran, starting with either B, R or S.
Xavier Delamarre and Ranko Matasović state that comes from Proto-Celtic "assembly, (feast of the) first month of the year", perhaps "assembly of the living and dead".
and divide the calendar into summer and winter seasons of six months, each season led off by a festival of several days marked with IVOS. This indicates an early version of the same traditional seasons as seen in later Celtic contexts: "For two divisions were formerly on the year, viz., summer from Beltaine (the first of May), and winter from Samuin to Beltaine".>
Allowing for variations between lunar and solar years and aligning the month names to the solar year's seasons, Samonios may have begun on the first quarter moon around May–June; if aligned to the modern Gaelic festivals Beltane, Lughnasadh, Samhain and Imbolc, Samonios might have begun around on the first quarter moon around April—May.
Order Name Days Etymology Interpretation Samoni Solar GaelicFestivals I-1 ? 29/30? Unknown meaning Sep-Oct Apr-May Mar-Apr 1 30 P-Celt. "assembly, (feast of the) first month of the year" (cf. O.Ir. bech-samain 'bee-swarm'; M.Ir. samain '[assembly on] the 1st of November'). A link to Gaulish samo- ('summer') appears to be a folk etymology. Oct-Nov May-Jun Apr-May 2 29 Potential cognate, Latin , P.I.E. . Delamarre suggests "month of fumigations". Nov-Dec Jun-Jul May-Jun 3 30 O.Ir. "stout, thick, fat", W. "thick, stout; great, large". Delamarre suggests "fat month". Dec-Jan Jul-Aug Jun-Jul 4 29 From *an-agantio- (the month 'in which one does not travel'), *aneg-antio ('month of protection'), or *ad-nigantio- ('month of ritual ablution'). Jan-Feb Aug-Sep Jul-Aug 5 30 Delamarre suggests "month of cold/winter". Feb-Mar Sep-Oct Aug-Sep 6 30 Delamarre suggests "month of invocations". Mar-Apr Oct-Nov Sep-Oct I-2 30 Unknown meaning Mar-Apr Oct-Nov Sep-Oct 7 29 Gaulish , O.Ir. and W. "winter"; O.Ir. mí gam "November" in Sanas Cormaic., Compare gamuin "calf", of the same root. Apr-May Nov-Dec Oct-Nov 8 30 "half" for "half the course of the sun"., or P.I.E. , "spring" for "half-spring". May-Jun Dec-Jan Nov-Dec 9 29/30 Possibly a month of horses or livestock. Jun-Jul Jan–Feb Dec-Jan 10 29 Month of the stag. Jul-Aug Feb-Mar Jan–Feb 11 30 O.Ir "fire, heat". Aug-Sep Mar-Apr Feb-Mar 12 29 Delamarre suggests "month of chanting". Sep-Oct Apr-May Mar-Apr
The lunar month The Coligny calendar as reconstructed consisted of 16 columns and 4 rows, with two intercalary months given half a column each, resulting in a table of the 62 months of the 5-year cycle. Whether the 5 years of the calendar plaque is part of a Metonic cycle of 19 year or 30-year cycle, the full length of the calendar is still debated.
Y1IC101 Y1RIV04 Y1GIA08 Y1AED12 Y2RIV16 Y2GIA20 Y2AED24 Y3RIV28 Y3IC232 Y3EQV35 Y4SAM39 Y4OGR43 Y4EQV47 Y5SAM51 Y5OGR55 Y5EQV59 Y1ANA05 Y1SIM09 Y1CAN13 Y2ANA17 Y2SIM21 Y2CAN25 Y3ANA29 Y3ELE36 Y4DVM40 Y4CVT44 Y4ELE48 Y5DVM52 Y5CVT56 Y5ELE60 Y1SAM02 Y1OGR06 Y1EQV10 Y2SAM14 Y2OGR18 Y2EQV22 Y3SAM26 Y3OGR30 Y3GIA33 Y3AED37 Y4RIV41 Y4GIA45 Y4AED49 Y5RIV53 Y5GIA57 Y5AED61 Y1DVM03 Y1CVT07 Y1ELE11 Y2DVM15 Y2CVT19 Y2ELE23 Y3DVM27 Y3CVT31 Y3SIM34 Y3CAN38 Y4ANA42 Y4SIM46 Y4CAN50 Y5ANA54 Y5SIM58 Y5CAN62
Each lunar year has 12 lunar months, six 30 day months, five 29 days months and a 29/30 day variable month. As synodic months are 29.53 days long, the calendar may overcome this by removing a day from a 30-day Equos month. The length of Equos may have been decided by the sighting of the first quarter moon, which start months in the calendar.
The first intercalary month is in year 1 at the start of the year before Samonios, the second appears between Cutios and Giamonios in year 3 in the middle of the year. The second has 30 days, the first is contested on whether it has 29 or 30 days. Intercalary months have set copying patterns from days across the months throughout the 5-year cycle to form their day notations.
McKay proposes the first intercalary month had 29 days, as the "30th" day of a 29-day month Cantlos, in year 1 would copy DIVERTOMV, a non-existent day. Olmsted notes it may be 30 days stating it is marked as a MATV month, and the remaining portion of the broken-off second digit of the Roman numeral for the last day potentially has a slant for XV instead of XIIII.
The start of the lunar month
Months are divided in two halves with ATENOVX between them. The first half has 15 days and the second has 15 days or 14 days with DIVERTOMV replacing the 15th day as a 'virtual' day for notations.
Pliny the Elder reported Celtic months began on the 'sixth day of the new moon'. The mistletoe, however, is but rarely found upon the oak; and when found, is gathered with rites replete with religious awe. This is done more particularly on the sixth day of the moon, the day which is the beginning of their months and years, as also of their ages, which, with them, are but thirty years. This day they select because the moon, though not yet in the middle of her course, has already considerable power and influence; and they call her by a name which signifies, in their language, the all-healing.
Classical writers counted days from the first visible moon, thus the 6th day would be close to the first quarter moon. When comparing the calendar's notations with Pliny's statement, the full moon would fall within days 7 to 9 and the new moon within 7a to 9a.
Full reconstruction
A full reconstruction of the calendar by McKay (2020) includes the latest information about the intercalary notations and the triple marks. Olmsted (2001) offers a previous reconstruction, which usefully aligns the notations with photographic images. RIG III (1986) presented an earlier in-depth description of terms with a reconstruction.
As a cycle of 19 years
If based on a Metonic cycle, this can be created using four 5-year cycles with the first year of the first cycle dropped and Equos being 30 days long on Cycle years 1 and 5, with dates moving within a range of 36 days from a solar date.
+ Helen McKay's Metonic Reconstruction Year Month Met. Years Cycle I1 Sa Du Ri An Og Cu I2 Gi Si Eq El Ae Ca 05, 10, 15 Y1 29 30 29 30 29 30 30 _ 29 30 30 29 30 29 01, 06, 11, 16 Y2 _ 30 29 30 29 30 30 _ 29 30 29 29 30 29 02, 07, 12, 17 Y3 _ 30 29 30 29 30 30 30 29 30 29 29 30 29 03, 08, 13, 18 Y4 _ 30 29 30 29 30 30 _ 29 30 29 29 30 29 04, 09, 14, 19 Y5 _ 30 29 30 29 30 30 _ 29 30 30 29 30 29
The Metonic Cycle, being 6940 days long, overruns the sun by 0.398396 days and the moon by 0.311620. This would require a 30-day Equos month reduced to 29 days around every 61 years to keep aligned with the moon. As the moon finishes roughly 0.0868 days ahead of the sun, the calendar will become a day ahead after 219 years, requiring a 29-day month skipped after 6,350 years or a 30-day month after 6,569 years.
As a cycle of 30 years
The calendar can perform as a 30-year cycle, using six 5-year cycles with a 30-day intercalary month dropped once every 30 years. If part of a 30-year calendar, it overruns the lunar phase by 0.1515 days, requiring a day to be removed from a 30-day Equos roughly once every 198 years.
However, the internal months show a larger variation in accuracy for the lunar phase of nearly 48 hours (1.44 to −0.65), making the ability to track the lunar phase of 30-years notably less accurate. The lunar/solar difference is larger at 1.4172 days, requiring a 30-day month to be skipped every 198 years.
This relatively fast slippage against the solar year would also add to the already large lunisolar swing, for a total of 75 days before a possible adjustment, further aggravating the solar discrepancy, and displacing seasonal festivals by up to two and a half months.
Sample month The month of SAMONIOS in year 2 is the only month without any missing fragments, preserving all its notations. Most patterns of notations are known and can be reasonably reconstructed, though their purpose or significance is not fully understood.
The title starts with M declaring it as a month, followed by the name and its type, thus M SAMON MAT reads as "M(onth) Samon(ios) Lucky/Good". Days are sorted in rows, with ATENOVX "Renewal" dividing the month in two halves. Each day has four columns for the peg-hole, Roman numeral, triple-mark, day type and any additional notations. The M of day type appears in the triple-mark column.
The count for the days are in Roman numerals with additive notation, after ATENOVX, the count is reset. The triple marks have either no value, ƚıı, ıƚı or ııƚ; some have M after the triple mark or in its place, which is part of the following day's type. Day types are vertically aligned with D "day" or N "night". Day notations that provide further information on whether days were swapped, additional notations for day type or festivals. The PRIN LOVDIN notation spans across type and notation.
+ MAT I N DVMAN IVOS II ıƚı M D IVOS III ƚıı D DVM IVO IIII M D V D AMB VI M D VII PRIN LOVDIN VIII D DVM VIIII ııƚ M D X M D XI D AMB XII M D XIII ƚıı M D XIIII ıƚı M D XV ııƚ M D I D DVMAN II ııƚ D TRINVXSAMO III D AMB IIII ƚıı M D V ıƚı D AMB VI ııƚ M D VII D AMB VIII N INIS R VIIII N INIS R X ƚıı M D XI ıƚı D AMB IVOS XII ııƚ M D IVOS XIII D AMB IVOS XIIII M D IVOS XV D AMB IVOS
Calendar notations Several different notations, each with their own pattern, are placed sequentially on the 12 lunar months of the calendar, interacting according to certain rules with the notations before them, often replacing them. After the basic notations are set, many days' notations are then moved to other days, creating visual chaos. Finally, the days of the intercalary months are filled with notations copied from certain days in the 12 yearly months.