Centran Calendar

The **Centran Calendar** is the main civil calendar used by the nations of the Tantalus Cluster, based on the rotation of humanity's homeworld of Centrum around its star Centrum Solaris.

## Time measurement

The completion of the unification of the nations of the planet Centrum into the Centrum Assembly serves as the epoch of the Centran Calendar. The dating of years is based on the movement of the planet Centrum around its star Centrum Solaris. Centrum takes 735 days and 23 hours to complete a single revolution around Centrum Solaris. A Centran year, or season, is equivalent to half of Centrum's orbital period around its star (367 days, 23 hours, 30 minutes), which coincides with the passage from the cold Winter year to the warmer Summer year.

Each year is in turn divided into two large divisions, the Equinox and the Solstice. The Equinox is defined as the moment the plane of the equator passes through the geometric centre of Centrum Solaris, when the day and night are of the exact same length all over Centrum. The Centran Calendar uses the first day of Equinox as the first day of the year. The Solstice is defined as the moment when Centrum Solaris reaches its farthest distance from the equatorial plane in the sky - and also the day when sunlight lasts the longest, if summer, or shortest, if winter. The start of the Solstice also marks the longest day of the Summer year and the shortest day of the Winter year, and marks the middle point of the Centran year. Equinox and Solstice both last for a period of 184 days, 23 hours, 45 minutes.

Leap years occur in the Centran Calendar every 48 years to account for Centrum's orbital period. During the leap year, a single extra day is added to the Solstice.

The cycles of the Centran moons Lysane and Lysara are used in older, Pre-Unification calendar systems to create a system of 12 months to each year in four cycles of 31-31-30 days each. Post-Unification, however, months are considered an antiquated aspect of the calendar.

'Bells' is used as a substitute for 'o'clock' in the Tantalus Cluster; for example, 'six bells' is equivalent to 'six o'clock'.

## Timeline

### Before Centrum Unification (BCU)

#### Thousands of years BCU

* Humans evolve on the planet of Centrum.
* c. 3,000 BCU
	+ The CDC-41-Gamma nebula forms in the Intergalactic Void near the Morgana Galaxy.
	+ The Advari evolve within CDC-41-Gamma, eventually forming the Holy Advari Empire.

#### Hundreds of years PCU

* Much of Centrum is unified under the rule of the Aberfane Kingdoms through commerce and diplomacy.

#### 2nd century BCU

##### 0190s BCU

* 0199 BCU
	+ Suicide of the husband of Queen Faridah Amindura of the Aberfane Kingdoms; Queen Faridah begins preparations to abolish Centrum's monarchy.

##### 0180s BCU

* 0186 BCU
	+ Queen Faridah declares her intention to be the last ruling monarch of Centrum, and orders her government and subjects to begin a transition to republicanism.

* Queen Faridah's three sons form the Tripathia Pact in opposition to their mother; civil war breaks out in the Aberfane Kingdoms, though Queen Faridah's faction is ultimately victorious; upon her death, the Aberfane Kingdoms transition to a parliamentary democratic republic known as the Aberfane Assembly.

##### 0170s BCU

* 0176 BCU
	+ Victoria Weaver voyages through the Glancewend Strait.

#### 1st century BCU

##### 0020s BCU

* 0023 BCU
	+ Symphony Base is established at Mare Symphoniae on the Centran moon of Lysara.

##### 0000s BCU

* 0005 BCU
	+ 14th Equinox:
		- The 6th Lysara Southern Survey Expedition surveys a pyroduct at Mare Somnia on the Centran moon of Lysara; it discovers an unknown crystalline substance, initially thought to be Hematite, samples of which are collected and dated.
	+ The "E-14 samples" are returned to Symphony Base, but defy chemical analysis; they are returned to Centrum for further study.

* 0003 BCU
	+ The Henshall Institute for Higher Learning publishes the groundbreaking "The Novel Relationship Between Exotic Hadrons and Gravitoelectromagnetism" paper, identifying the substance in the E-14 samples as Riberite; the material Drift is isolated from Riberite; it is discovered that Drift can produce directional gravitoelectromagnetic fields when subjected to an electric current.
	+ The unification of Centrum begins under the banner of the Centrum Assembly.

* 0001 BCU
	+ A.R. Courvoisier leads a team in publishing the scientific paper, "Unpredictable Particle Motion Within Artificial Spacetime Topologies".

### Post-Centrum Unification (PCU)

#### 1st century PCU

##### 0000s PCU

* 0001 PCU
	+ The unification of Centrum into the Centrum Assembly is completed.

* 0003 PCU
	+ Mathew Moura of the Centrum Multinational Aerospace Institute leads the construction, testing, and flight of the first successful prototype of the Drift Drive; the first spacecraft equipped with Drift Drives begin to chart and settle nearby planets and moons within the Centrum System.

* 0007 PCU
	+ Valentina Nakayama publishes the scientific paper, "A Theoretical Framework for the modelling of the Relationship Between Exotic Hadrons and Gravitoelectromagnetism", describing the Nakayama Mechanism, the means by which Drift produces gravitoelectromagnetic fields.

* 0008 PCU
	+ Paul Bessa and Antonio Azevedo publish their scientific paper "The Derivation of a New Universal Theory of Relativity"; the Azevedo-Bessa Theory of Universal Relativity is named in their honour and paves the way for the construction of the first Drift Gate.

##### 0010s PCU

* 0010 PCU
	+ The Hadimus Gateforge is constructed over the planet Hadimus by Santana Starworks.
	+ Construction of the first Drift Gate begins near the planet Destrum.

* Sometime between 0001 PCU and 0017 PCU
	+ Formation of the Savaragi-Rota Alliance.
	+ The Arasinian Commerce War is fought between the Savaragi-Rota Alliance and the Centrum Assembly; the Centran Defence Force is victorious at the Battle of Lyrion Point.
	+ Dissolution of the Savaragi-Rota Alliance.

* 0017 PCU
	+ The Centrum-Pioneer Drift Gate is completed near Destrum.
	+ 62nd Solstice:
		- Ships of the CDF Discovery Service reach the Pioneer System, completing Humanity's first interstellar jump outside of the Centrum System.
	+ The first Human settlement outside of the Centrum System is established in the Pioneer System on the planet of Storm.

##### 0020s PCU

* 0021 PCU
	+ Construction of the Wainwright Gateforge begins over the ice giant of Yashoda in the Pioneer System.

* Late 0020s PCU
	+ Advances in Drift Gate construction render plans to expand further from the Pioneer System redundant; construction of the Wainwright Gateforge is abandoned.

##### 0030s PCU

* 0034 PCU
	+ The Rialtis System is colonised.

* 0038 PCU
	+ K.D. Oursler publishes the scientific paper, "The Natural Abundance and Concentration of Exotic Hadrons on Centrum's Crust and Mantle".

##### 0040s PCU

* 0042 PCU
	+ The Keeper's Dance System is colonised.

* 0047 PCU
	+ T.I. Bogdanov publishes the scientific paper, "Study on the Practical Viability of Drift Capture After Decomposition".

##### 0050s PCU

* 0051 PCU
	+ The Axius System is colonised.

* 0053 PCU
	+ Great Merician Exile; a colony expedition disappears and believed lost by the Centrum Assembly; under the leadership of Adam Meric, the survivors establish the Merician Freehold.

* 0054 PCU
	+ Keeper's Dance Fleet Yards loses its license to construct Drift Gates for the Centrum Assembly; the license for gate-building is handed to Grathan Gateworks.

#### 2nd century PCU

##### 0100s PCU

* 0107 PCU
	+ Battle of the Wainwright Gateforge: a CDF force led by Post Captain Michael Cormier defeats the Crownskull Buccaneers over Yashoda; despite the decisive CDF victory, the Crownskull Buccaneers ultimately reconvene as a pirate band.

##### 0170s PCU

* Halpern's War is fought between the Centrum Assembly and the pirate forces of Jocastus Halpern; it is the last action of the Centran Defence Force involving major combat for over a century.

##### 0180s PCU

* 0182 PCU
	+ The Braidwood Expedition conducts the first survey of the Seravis Major System.
	+ 133rd Equinox:
		- The first survey team led by Post Captain Raphael Colegrove makes landfall on Seravis Major; it is attacked within hours, leaving Post Captain Colegrove the only survivor.
	+ 134th Equinox:
		- Airborne hallucinogens encountered during the exploration of Seravis Major drive Post Captain Colegrove to kill two of his staff before he is killed by Centran Marines.
	+ The Seravis Major System is put under quarantine.

* 0184 PCU
	+ Jaiden Lockwood makes the first passage of the Atamara Crossroads System.

#### 3rd century PCU

##### 0210s PCU

* 0210 PCU
	+ The return gate to Meric's Keep is repaired by the Merician Freehold; contact between Mericia and the rest of Tantalus is re-established.
	+ Meric's Keep is converted into a trading post.
	+ Towershield Station is constructed.

* 0219 PCU
	+ 84th Equinox:
		- 816 convicted criminals are settled on Dalstaff II by the penal barque *Grey Stablemaid*, and are left with tools to begin the construction of a planetary prison.

* The colonisation of the Frontier systems of Atamara Crossroads, Teldrin, Dalstaff, and Maiala's Rest begins.

##### 0220s PCU

* 0222 PCU
	+ Blair Bellamy leads an expedition to chart the edges of the Cardeus Brink System, the farthest any Human has yet travelled from Centrum.

##### 0230s PCU

* 0230 PCU
	+ The first penal settlements on Dalstaff II are completed.

* 0234 PCU
	+ The first People's Modernist Party government of the Centrum Assembly, led by Prime Minister Lucia Castilio, takes power.

* 0236 PCU
	+ The Castilio Government approves the *Wanderer* Project to colonise the Firewatch System.

* 0239 PCU
	+ Under the command of Post Captain Blair Bellamy, the *Wanderer* departs for the Firewatch System from the Rialtis System.

##### 0240s PCU

* 0247 PCU
	+ The *Wanderer* arrives in the Firewatch System and colonises Firewatch II.

* 0249 PCU
	+ 112th Solstice
		- The Firewatch-Rialtis Drift Gate is completed, linking the Firewatch System to the rest of the Centrum Assembly three months ahead of schedule.

* Amid rampant piracy in the four Frontier systems, six *Linford Island*-class Coastal Defence Ships are assigned to the region by the Centrum Assembly.

##### 0250s PCU

* 0257 PCU
	+ *Fundamentals of Mineralogy: Minerals and Their Different Properties*, by Jirou Fujioka, is published by Cognizione Books.

##### 0270s PCU

* Start of the Great Famine.

* 0275 PCU
	+ The *Linford Island*-class Coastal Defence Ships are replaced in Frontier service by their derivative vessels, the *Florencia*-class Outrider.

* 0277 PCU
	+ *Wanderer* bombing: the *Wanderer* Museum in orbit of Firewatch is destroyed in a suicide bombing by a Frontier terror group; 511 people are killed on the station; thousands more die in debris strikes on the planet's surface in the weeks afterwards.
	+ The 277 Memorial Station is constructed and placed into orbit of Firewatch II.

##### 0280s PCU

* 0282 PCU
	+ The Second Edition of *Fundamental Principles of Astronautical Engineering*, by Asha D. Malewezi, Beatrycze N. Chlebek, and Setiawan J. Moore, is published by Liddenworth.

* 0286 PCU
	+ The *Tripathia*-class Third-Rate Ship-of-the-Line is introduced into service in the Centran Defence Force.

##### 0290s PCU

* 0290 PCU
	+ 176th Solstice:
		- Primrose Incident: an altercation between Frontier Militia forces and the *Primrose*, a Centran humanitarian aid vessel, in the Maiala's Rest System ends violently; the Red Bannerets led by Kaito Hakim are provoked by the incident to launch a coup in the Maialan capital of Second Landing, seizing control of the planet; revolutionary violence spreads from Maiala's Rest to the three other Frontier systems of Teldrin, Dalstaff, and Atamara.
	+ 179th Solstice:
		- The four Frontier systems confederate as the Frontier Union and declare independence from the Centrum Assembly.
		- First Battle of Axius: Frontier Union forces led by Arcelia Abescal and the Paleborn raid the Axius System; start of the Frontier War.
	+ The Frontier Union mounts the Tandil Rush offensive against the Centrum Assembly; Centrum loses the Seravis Major and Cardeus Brink Systems.
	+ The Treaty of Mizudori is signed between the Centrum Assembly, the Frontier Union, and the Merician Freehold, confirming the Merician Freehold's neutrality.

* 0291 PCU
	+ *Introductory Transrelativistic Physics: Volume 1*, by Gabriel Fonseca, is published by Axius Institute Press.

* 0294 PCU
	+ The fronts of the Frontier War stabilise in the Axius and Valeria Sibus Systems; the Battle of Validar II is fought.
	+ *Principles of Interstellar Navigation*, by Drahomíra Vlček, is published by Liddenworth.

* 0297 PCU
	+ Winston Redfield commands the CSV *Barricata*.

* 0298 PCU
	+ The Fourth Edition of *Quantum Mechanics: Volume 1 - Subatomic Physics*, by Amar Narang, is published by Axius Institute Press.

* 0299 PCU
	+ The Frontier Union constructs their only dreadnought of the war, the *Arashi-Sakara*.
	+ Fourth Battle of Axius; Centrum Assembly victory.

#### 4th century PCU

##### 0300s PCU

* 0300 PCU
	+ The Frontier Union begins peace negotiations with the Centrum Assembly.
	+ Battle of the Atamara Crossroads; Centrum Assembly victory; Post Captain Cassandra Farren mistakenly orders the destruction of the CSV *Acrisius* in a fratricide incident; its cover-up leads her to leave the Centran Defence Force.
	+ End of the Frontier War.
	+ Keeper's Dance Fleet Yards begins the *Huntress*-class project.
	+ The Black Centenary: in the Frontier War's aftermath, civilisation in the Tantalus Cluster nearly collapses; profound food scarcity affects the entire cluster and most government functions cease; scientists predict an extinction-level event from the Great Famine.

* 0301 PCU
	+ The nebula CDC-41-Gamma is discovered by astrophysicist Dr. Sadavar Edric, working onboard the Carina Observatory in the Cardeus Brink System.
	+ The Avalon Exploratory Initiative is formed by the Centrum Assembly, Frontier Union, and Merician Freehold in a final effort to reach CDC-41-Gamma and return with resources to save Tantalus.
	+ Plans for Edric's Gate begin; Cardeus Terminal is renamed Gatehouse Station; the area around Gatehouse Station becomes a staging ground for the assembly of Edric's Gate.
	+ Cassandra Farren obtains her Letter of Marque and recovers the the *Huntress*-class prototype from the Rialtis System, rechristening it the *Guinevere*.

* 0304 PCU
	+ Travis Lock releases *Love Me Once Again*.
	+ The construction of Edric's Gate is completed; Sadavar Edric retires and is succeeded as director of the Avalon Exploratory Initiative by his adopted daughter Elizabeth Ancelet.
	+ The *Guinevere* intercepts the slaver *Black Rabbit*.
	+ The Avalon Expedition Fleet assembles in the Cardeus Brink System.
	+ 45th Summer Solstice:
		- The Avalon Expedition Fleet deploys through Edric's Gate to CDC-41-Gamma, but is scattered on its arrival.
		- The Frontier Union outrider *Mariana* is destroyed making first contact with the Holy Advari Empire, death of Edwin Darwish.
		- The gatehauler GH-0007-VG is destroyed
		- The *Triumph* illegally accompanies the fleet and is also scattered.
	+ Inquisitor Castian Vadric is tasked by Empress Valendra the Sixth of the Holy Advari Empire to investigate reports of the Avalon Expedition Fleet on the edges of CDC-41-Gamma.
	+ 48th Summer Solstice:
		- Lauralyn Conduits are discovered in CDC-41-Gamma by the Avalon Exploratory Initiative.
		- The crew of the *Guinevere* encounter the wreck of GH-0007-VG and rescue a single wounded survivor.
	+ Avalon Bombings; Michael Favara and Tamika Jinn are killed; the frigate *Abigail* is destroyed.
	+ 98th Summer Solstice:
		- First Human exploration of a pulsar system by the *Guinevere*.
		- Elizabeth Ancelet and Cassandra Farren discover edible vegetation on the system's vitrified planet, as well as a wrecked Advari spacecraft and the remains of its pilot.
	+ Elizabeth Ancelet and Cassandra Farren lead the *Siochana* back to the pulsar system to begin harvesting operations; the *Triumph* establishes contact with the *Avalon* after two months; *Triumph* hostage incident.
	+ The CSV *Shabayev*, CSV *Bracewell*, CSV *Republic*, and a Gatehauler under the command of Vice Admiral Winston Redfield capture Castian Vadric and engage with two Advari ships; death of Ensign Lydia Telfer; the *Bracewell* and the *Republic* are destroyed and the Gatehauler is abandoned.
	+ The Advari seize the Gatehauler and take it into the Aegis of Invia for examination; Unioner vessels of the Avalon Expedition led by Captain Omar Maalsuwda track them and establish a holdfast nearby to observe their movements.
	+ The CSV *Shabayev* re-establishes contact with the *Avalon*; Winston Redfield attempts to seize control of the *Avalon* but stands down after facing a general mutiny from the Expedition Fleet.
	+ The Avalon Expedition Fleet moves to the pulsar system and establishes a harvesting colony on the vitrified planet, which they christen "the Greenhouse".

* 0305 PCU
	+ 100th Equinox:
		- The Avalon Expedition Fleet receives a distress signal from the *Friendly Expedience*, the *Swift Conveyance*, and a Gatehauler; the *Guinevere* successfully rescues the three ships and they re-unite with the fleet.
	+ Battle of Maalsuwda's Holdfast: the *Guinevere* encounters Maalsuwda's Holdfast; Maalsuwda agrees to evacuate and re-unite with the *Avalon*, but the fleet is attacked by the Advari; the *Sutedo*, *Jamake*, *Whiplash*, and *Seraphina* are lost.
	+ Empress Valendra the Sixth confronts Lord Cardinal Hastus Arvannis over the true nature of the Faith Eternal and CDC-41-Gamma; she leaves Advar Primaris with him.
	+ 154th Equinox:
		- Raid on the Aegis of Invia; the *Guinevere*, *Shabayev*, *Tserekai* and *Hotstepper* return to the Aegis of Invia and successfully recover the Avalon Expedition's last Drift Gate component from the Holy Advari Empire.
		- Deaths of Larsen, Pritchard, Waters, and High Cleric Darsellia Lantris.
	+ 160th Equinox:
		- Battle of the Greenhouse; the Avalon Expedition Fleet is attacked by three Advari lightships, but successfully completes a Drift Gate and chooses to abandon CDC-41 Gamma
		- Deaths of Winston Redfield, Faraday, Bridget Volkova, Rachel Weisheimer, Felix LaBelle, Keagan Quintero, and Darin Heijai.
		- Empress Valendra the Sixth accompanies Lord Cardinal Hastus Arvannis to the centre of the Wheel.

## Behind the Scenes

*The Sojourn's* calendar was extensively described by Gabriel Fonseca in a Patreon post, "The Centran Calendar System". To account for Centrum's large orbit around its star, a Centran year is not equivalent to its orbital period, but instead roughly equates to the length of an Earth year. It was originally intended that the Centran year *would* be equivalent to its orbital period, and that the season would be the Earth year equivalent, hence why "light-seasons" are mentioned in *The Sojourn* as a unit of distance. However, this was found to be too confusing, and so it was decided to make the Centran year (half the planet's orbital period) equivalent to an Earth year.

## References and Notes

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Gabriel Fonseca, "The Centran Calendar System"
2. ↑ "*Centrum Broadcast Radio: 45th of Solstice, 304 PCU*"
3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 The Sojourn: Worlds of Tantalus: The Centrum Assembly
4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 The Sojourn: Drift and Drift Gates - Avalon Archives
5. ↑ 5.0 5.1 5.2 *Dust and Shadow*
6. ↑ 6.0 6.1 6.2 6.3 The Last Queen of Centrum | Official Lore Short
7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Firewatch | Worlds of Tantalus | The Sojourn
8. ↑ 8.0 8.1 8.2 Drift - Discovery and Properties | Official Lore Short | The Sojourn
9. ↑ 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 9.11 9.12 9.13 9.14 9.15 9.16 9.17 Gabriel Fonseca, *The Science of Drift*
10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 10.11 10.12 10.13 10.14 10.15 10.16 *The Sojourn Visual Dictionary - Edition One*
11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 11.6 Pioneer | Worlds of Tantalus | The Sojourn
12. ↑ 12.0 12.1 12.2 The Merician Freehold | The Sojourn Lore
13. ↑ 13.0 13.1 13.2 The Sojourn: Tripathia Class Ship of the Line | Ship Breakdown
14. ↑ Piracy In Tantalus | Official Lore Short
15. ↑ The Braidwood Expedition | The Sojourn Lore Short
16. ↑ 16.0 16.1 The Grey Stablemaid (feat. Milseán) | A Sojourn Original Folk Song
17. ↑ The Sojourn: Worlds of Tantalus: The Centrum Assembly states that the *Wanderer* took almost six years to reach the Firewatch System, however all subsequent sources have stated that the journey took eight years.
18. ↑ The Sojourn: Wanderer Class Explorer Platform | Official Ship Breakdown
19. ↑ 19.0 19.1 The Sojourn: Florencia Class Outrider | Official Ship Breakdown
20. ↑ 20.0 20.1 Maiala's Rest | Worlds of Tantalus | The Sojourn
21. ↑ 21.0 21.1 21.2 The Primrose Incident | Official Lore Short | The Sojourn
22. ↑ First Battle of Axius | Official Lore Short | The Sojourn
23. ↑ 23.0 23.1 *Theirs Not to Reason Why*
24. ↑ 24.0 24.1 The Sojourn: Huntress Class Ambush Corvette (Guinevere) - Ship Breakdown
25. ↑ The Black Centenary | Official Lore Short | The Sojourn
26. ↑ 26.0 26.1 *Centrum Broadcast Radio: 45th of Solstice, 304 PCU*
27. ↑ 27.0 27.1 27.2 *The Cold Divide*
28. ↑ 28.0 28.1 *The Promised Land*
29. ↑ 29.0 29.1 *Inclement Weather*
30. ↑ *Yesterday's War*
31. ↑ 31.0 31.1 *Theirs Not to Make Reply*
32. ↑ 32.0 32.1 32.2 *Beneath The Banner*
33. ↑ 33.0 33.1 *Contact, Wait Out*
34. ↑ *Where Angels Fear to Tread*
35. ↑ *Forlorn Hope*