Allwanduirian years

An Allwanduirian year is equivalent, relatively speaking, to roughly 54,28762% of a year on Earth, so 198,2814 days, or 198 days, 6 hours and 45 minutes. This is due to the fact that the planet orbits around a Red Dwarf, smaller and weaker than our Sun, thus revolving closer to it, 76,530,000 km away from it in average (this is also 1 ASSOA – Allwanduirian Solar System Official Unit).
An Allwanduirian day lasts the equivalent of 20 hours and 15 minutes on Earth (20,25 hours, 0,84375 day). From that data, we can tell that an Allwanduirian year is divided in 235,00017 Allwanduirian days. This is, in fact, very precisely 235 days, with too many decimals left out.

Calendar

Origins

The current calendar was invented by a Non-Talker astronomer of the 19th Earth century called Śíelzwët (according to the Database of Historical Figures' Names for Non-Talkers).
He decided of the year 0 based off a belief from the main religious current, according to which (and his own calculations) this was the time when Allwanduirians were given "the Wit", alone among the sentients. Śíelzwët, as a Non-Talker and a scientist, had of course no affiliation to this religion, but adopted the idea in hope for an increase in interspecies collaboration regarding scientific research.
Śíelzwët chose the start of the year from an astronomical phenomenon; every 12 AY, the planet Gaigo, a telluric giant following a highly elliptical course around the star, comes so close to Allwanduir that its course is altered, resulting in a year with 187 AD.
The critical gravitational influence of Gaigo over Allwanduir, known as "the Pull" and responsible for acute natural catastrophes (e.g. tides), spans on an actual 287 days, but the calendar was adapted to account for most of the altered period.

Conversion

January 1st, 2019 on Earth was roughly equivalent to the 54th AD of the 8193 AY. The year 8194 begins on June 3rd on Earth, at 3.12 PM.

Rules of thumb:

1 AD = 0,84375 ED

1 AY = 198,2814 ED

1 EY = 1,842 AY

1 EY = 432,88 AD

1 AY = 235 AD

The format of an Allwanduirian date is simply DD/YYYY.
Rough estimations of durations in Allwanduirian years can be made by dividing the amount by 2, but more precise values will be gotten from 1,842.

BN

Historical dates are expressed as "BN" or "AN", which stands for "before now" or "after now". The "now" is not the current year but a fixed date: 121/7500. That means that "0 BN/AN" will be situated in the year 7500, or (from AY 8193 / EY 2019) 692 AY ago, or 375,7 EY ago (1643).

Note: the fact that a regular Allwanduirian year is exactly 235 Allwanduirian Days remains unexplained to this day. No scientific evidence ever supported any theory on a kind of interbodies synchronisation.
AD: Allwanduirian Day
AY: Allwanduirian Year

Type

Natural