Colonial calendar

This article presents known information about the calendar(s) used in the twelve worlds. For the specific chronology of events in the re-imagined series and Caprica, see Timeline (RDM).

A Colonial calendar would be common to the twelve worlds, but there is little evidence of its structure. We don't even know whether there is one calendar for all the colonies or several different systems.

Specific dates were usually avoided in the re-imagined series: the closest depiction of an actual calendar comes from the dossier of William Adama's career in the episode "Hero" (see below). On the other hand, the aired episodes of Caprica contain a number of prominent and fairly consistent references, indicating that the production people have settled on a basic system which may or may not be specific to the planet Caprica.

Units of Time

The units used to express timespans in the re-imagined series and Caprica appear to be identical to those of the Gregorian calendar, with 24-hour days and approximately 365-day years. The best example of this is in "Tigh Me Up, Tigh Me Down," where Baltar says that each of his tests takes 11 hours. As there are 47,905 tests, amounting to 526,955 hours' worth of tests, this will take him 21,956 days, or 60.1534 years (as confirmed by Baltar's Internal Six).

Although the calculation uses an average year of 365 days, without taking into account leap years, it could be due to a mistake rather than a deliberate revision. A year comprising 52 weeks is revealed in "Rebirth" during the airing of a Cubits & Pieces clip. Further, days of the week are given in various episodes of Caprica: Saturday (Rebirth), Monday (Gravedancing) and Wednesday (Ghosts in the Machine).

Ronald D. Moore: "I dropped many other terms from the old show like 'centon' (a unit of measurement) and 'yahren' (year) because I felt they distracted from the mood I was trying to create and they sounded a bit silly to my ear" (RDM's SyFy blog). Nevertheless, the word yahren does appear in the Cylon specifications examined by the Armistice Officer (Miniseries, Night 1).

The Calendar from Caprica

Caprica has already shown a number of calendar dates which appear to be based on the Roman calendar. Since the show is mostly set on Caprica, we don't know whether the calendar is specific to the colony or common to the twelve worlds.

The Lev bombing memorial event was scheduled for "Junius 7th, Mid-Day" according to Joseph Adama's invitation (Rebirth).
The recording of Ben Stark's interrogation is dated "APRILUS 9TH YR41". Agent Jordan Durham says that it was made a year ago (The Reins of a Waterfall).
Moments later, Durham looks at what appears to be the current issue of Caprican Tribune, which is dated "Aprilis 11, YR 42" (The Reins of a Waterfall).
Tad Thorean's date of birth is given as "06-04-27YR" on his driver's license, which also contains less readable dates of issue and expiration (Know Thy Enemy).
The Delphi Convalescent Institute logo on their letter to Amanda Graystone includes the following text: "Established YR 01" (The Imperfections of Memory).
The deadline for Daniel Graystone to deliver 100,000 robots was moved up to "the seventh", which is "next week" (End of Line). We don't know if this is a day of a month, but it could become significant should we obtain more information.

The same style of calendar is used in the Syfy blog The Caprican, although certain events are dated differently than on the show, apparently because the blog's fictional dates of YR42 were based on real-world airdates (the first season premiered on January 22, 2010). The following names of months have been established so far in The Caprican: Ianuarius, Februarius, Martius.

The episode "End of Line" establishes the existence of a holiday named Eros Day. This holiday was first mentioned in articles of The Caprican posted in February 2010, a month before the episode aired, and is a clear parallel to St. Valentine's Day.

Analysis of William Adama's Dossier

In "Hero" William Adama's dossier can be clearly seen. While this document is fairly accurate in terms of Adama's personal history, the dating scheme used in the document seems to be flawed, particularly in lieu of previously established methods of timekeeping demonstrated in the series.

Here are a list of dates from Adama's past that Adama's dossier contains:

H5/21290 Birth of William Adama

D6/21311 First commission, Battlestar Galactica, fighter squadron

E4/21312 Commendation for shooting down Cylon fighter in first combat mission.

D5/21314 Mustered out of service post-armistice

R6/21317 Served as Deck Hand in merchant fleet and as common […] aboard inter-colony tramp freighters

D1/21331 Recomissioned to Fleet

D6/21337 Major: Battlestar Atlantia

R8/21341 Executive Officer: Battlestar Columbia

C2/21345 Commander: Battlestar Valkyrie

C2/21348 Commander: Battlestar Galactica

This provides some interesting information. The fields in the format X#/##### appear to be dates, with the five-digit string following the solidus apparently corresponding to the year.

The following can be deduced from this document:

This episode marks the 45th anniversary of Adama's commissioning, which puts it in the year 21356 and makes Adama 66 years old. On the other hand, Joseph Adama says that William is eleven in the Caprica pilot, which is set in 58 BCH, making William Adama 69 years old during the miniseries.
Adama spent three years in between being mustered out and finding a job on a tramp freighter. We may speculate that it was during this time that his relationship with first wife Carolanne Adama deteriorated.
Adama spent a total of 14 years serving in the merchant fleet.
Adama met Tigh roughly 30 years ago (Torn). That would be 21326, which correctly puts it in the middle of Adama's merchant fleet service.
Adama was a major by the time he arranged for Tigh to be reinstated in the fleet (Scattered), which means that at least six years passed in between Adama's recomissioning and Tigh's.
Ronald Moore stated in his podcast for "Scattered" that the flashback scenes in that episode took place 20 years before that episode, or in 21334. In fact, they appear to span at least an eleven-year period between 21326 (Adama and Tigh's first meeting) to 21337 (Adama's promotion to Major).
The first Colonial Day, marking the unification of the Colonies, was probably in 21302. The one celebrated in "Colonial Day" was the 52nd, and it is now two years later.
Galactica herself is at least 45 years old. Other battlestar's minimum ages prior to the Fall: Atlantia at least 13, Columbia at least 11, and Valkyrie at least 8.

Additionally, an error occurs in "Hero". Dialogue from this episode claims that Adama served on Valkyrie one year prior to the Fall of the Twelve Colonies, putting the date of Lt. Daniel "Bulldog" Novacek's capture at 21352-53. However, Adama's command of Valkyrie ended in 21348, which means that Adama commanded Galactica for eight years. It has already been established in dialogue from the Miniseries, "Act of Contrition", and "The Farm".

Inference about dating structure

If the five-digit string following the solidus is in fact the year, as seems inescapable based on the above, the letter-digit sequence before it must indicate the position in the year. There are 260 unique letter-digit sequences of that format, which may indicate a shorter year in the calendar, essentially a year of twenty-six ten-day weeks. However, what has been revealed about Colonial timekeeping is too incomplete to draw any conclusions.

However, if the above is to be inferred, a striking inaccuracy occurs because of this service record. Prior episodes have firmly established that the Colonial year is analogous to one Earth year of 365 days. In "Tigh Me Up, Tigh Me Down", the Cylon detector takes 11 hours to thoroughly test each blood sample. As there are 47,905 tests (526,955 hours) this will take him 21,956 days, which Six then computes will take approximately 60 years, the same as it would here. The dating further established in "Lay Down Your Burdens, Part II", "Battlestar Galactica: The Resistance", and "Occupation" also support this comparison.

On the other hand, the Colonial numerical system may start with the numbers zero through 99, then continue with A1 through Z9, followed by AA, AB and so on. This would mean that the first day of the year is 1 and the last day, the 365th, is represented as AF.

It is astonishing to learn that the Colonials have -- or believe they have -- over 21,000 years of recorded history. By comparison, Pythia was said to have recorded her prophecies 3,600 years ago (The Hand of God) and the Great Exodus from Kobol took place just 2,000 years ago. On Earth, Human civilization is only about 6,000 years old.

Different Dating Methods

The system used in the dossier is only the most prominent example of dates in the re-imagined series. A closer analysis of other items reveals a number of different methods. It is unclear whether these were actual calendar proposals or random alphanumerics which were never intended for closer inspection.

The note "SEVENTH MILLENNIUM OF TIME" appears on paper cubits. It is a line from President Adar's toast in the original series pilot: "As we approach the seventh millennium of time, the human race at last will find peace, thanks to you."
Lee Adama's date of birth is "432:979:021" according to his service record.
William Adama was "to report to Aerilon High Command, Base 12 at 038:847:857" in his letter of reinstatement in the Colonial Fleet. His shuttle was scheduled to leave for Aerilon "at 024:639:374".
Gaius Baltar's executive order concerning settlement on New Caprica became law "this 23rd day of 04859".

Adama's resignation letter at the end of the Hero appears to be dated in an entirely different format compared to the system used in his dossier. While difficult to read clearly, it appears to be dated "27/89/9923". On the other hand this may not be a date but some form of document ID number.
In addition, the execution order written by the Cylon Occupation Authority and signed by then-President Gaius Baltar is dated "this second day of 3454-91" (Occupation). This may be a date on the Cylon Calendar but this would not explain why the Cylons wanted this "official" document to use their dating system instead of that used by the Colonials.
Kara Thrace's disciplinary record in "Maelstrom" notes that a proceeding was "held on 22/E4/3F3". This appears to be a date, but there is no confirmation.
The medal of valor given to Socrata Thrace uses a day number and alphanumerics to specify the current date ("this ...th day of ..."), whereas Socrata's period of service is expressed using two sets of alphanumerics. The exact numbers and letters are currently unreadable.