@Ladsgroup Do you know where the Wikidata conversion table is stored and how to add new entries?

In T247027#5947353, @Lea_Lacroix_WMDE wrote:

@Ladsgroup Do you know where the Wikidata conversion table is stored and how to add new entries?

I wondered a while ago, the answer is unitConversionConfig.json and I added the fact on the wikibase doc on mediawiki.

I think this would be rather easily doable.

Indeed. I don’t know if a unit has previously be added to the translation table after the first initialization, but the problem seem to be that creating a ticket and pinging everyone for such simple task seems like an overkill procedure. I don’t know if someone less community involved or a newbie would even try to do something like this.

Can we imagine a procedure with more visibility with a simple set of criteria on wether or not a unit is eligible for inclusion in this translation table ?

In fact the unit corresponds to the « mean gregorian year », and I created a fresh item for this, to be sure there is no pollution from inconsistent datas on Wikipedia articles.

I stopped reading after the first paragraph of the "Description" because it is false. I quote it here, in case it is edited, so my comments will remain clear.

The annum unit is used in Wikidata statements to represent half life of isotopes, this is shown by this query. 1 annum = 1 gregorian mean year = 31 556 926 s The value is also cited by the NASA in this document as used currently for calendar calculation by them.

Based on comments at https://www.wikidata.org/wiki/Wikidata:Contact_the_development_team#%C2%AB_annum_%C2%BB_conversion_? I surmise that 31 556 926 s is based on this paper by Holden et al. In that paper the length of the tropical year near AD 2000 is asserted to be 31 556 925.445 SI seconds. But the mean Gregorian year is not the same as the tropical year.

As the NASA document (although intended for K-12 education) correctly states, the mean length of a Gregorian calendar day is 365.2425 calendar days. If we define a second to be 1/86400 calendar day, this is equal to 31,556,952 seconds. The length of these days has been measured in various ways, initially by simply observing the rising and setting of the Sun; later with astronomical observations of the Sun and stars to calibrate mechanical clocks in observatories. Today, atomic clocks are used but leap seconds are introduced at irregular, unpredictable intervals to keep calendar days in alignment with the observed rotation of the Earth on it's axis. So no precise SI equivalent can be given; it all depends on what period of time you decide to average over, and how much the rotation of the Earth on it's axis disagreed with atomic clocks during the averaging period.

Looking a bit further, Holden et al. give 31 556 925.9747 as the number of ephemeris seconds (a predecessor to the SI second) as the mean length of a tropical year near 1900. When rounded to the nearest second, this agrees with the length of a year adopted by Audi et al. on page 6.

We updated the unit conversion config last year (T270252 / T267644), and also Q87193822 was merged by @Toni_001 into Gregorian year in the meantime. Is this task still relevant, or can it be closed?

I see no reason to keep it open.