<p><a href="https://en.m.wikipedia.org/wiki/Template:WEEKDAYNAME" rel="nofollow noreferrer">Wikipedia uses</a>: mon, tue, wed, thu, sat, sun.</p>

<p><a href="https://en.wikipedia.org/wiki/ISO_week_date" rel="nofollow noreferrer">ISO 8601</a> defines an exchange standard for dates based on weeks and days, which looks like this: 2017-W01-3 or this 2017W011 (Year, ISO week number, number of day of week starting with Monday). Not so surprisingly it does not standardize names of days as far as I can tell. </p>

<p>So you could claim to use ISO-8601 conventions and simply use 1-7 (starting with Monday).</p>

<p>A comprehensive listing of abbreviations of day names for European countries is given by the European Medicines Agency for <a href="http://www.ema.europa.eu/docs/en_GB/document_library/Other/2012/04/WC500124995.pdf" rel="nofollow noreferrer">blistered drugs</a> for the curious.</p>

CC BY-SA 3.0
2017-03-17T23:33:15.790Z
2017-03-17T23:33:15.790Z
Grimaldi
<p><em>comments converted to community wiki</em></p>

<p>The day of the week by itself has no use in astronomy unless you also know the corresponding calendar date. And since the day of the week is computable from the calendar date, it's really just superfluous information. Nevertheless, most astronomy apps such as Sky Safari seem to use the first three letters (in English) abbreviating the names for the days of the week. This use seems to conform with the <a href="https://en.wikipedia.org/wiki/ISO_week_date" rel="nofollow noreferrer">ISO week date standard</a>.</p>

CC BY-SA 3.0
2017-01-15T22:05:10.087Z
The week does represent one quarter of the Moon's phases, and the days are named after the five classical planets, the Moon and the Sun.
LocalFluff
CC BY-SA 3.0
2017-01-16T08:25:51.953Z
…except Saturday in all Nordic languages, where it means "washing-day".
pela
CC BY-SA 3.0
2017-03-18T17:53:05.250Z
Other languages also diverge in some cases; e.g. Italian uses _sabato_ (Sabbath) and _domenica_ (day “of the Lord”) for Saturday and Sunday, respectively, and German uses _Mittwoch_ (“middle of the week”) for Wednesday.
chirlu
CC BY-SA 3.0
2017-01-15T20:47:37.353Z
2017-01-15T20:47:37.353Z
James K
<p>Is there a set of standard abbreviations for the days of the week for use in astronomy? I couldn't find any reference to it in the <a href="http://www.iau.org/static/publications/stylemanual1989.pdf" rel="nofollow">The IAU Style Manual (1989)</a>.</p>

CC BY-SA 3.0
2015-06-27T11:18:42.323Z
I'd be surprised if there was any set standard convention. The day of the week by itself has no use in astronomy unless you also know the corresponding calendar date. And since the day of the week is computable from the calendar date, it's really just superfluous information. Nevertheless, most astronomy apps such as Sky Safari seem to use the first three letters abbreviating the names for the days of the week, so you're probably safe going with that.
David H
CC BY-SA 3.0
2015-07-08T08:44:21.847Z
In English @barrycarter :-p
Nabigh
<standards>
Abbreviations for days of the week
Nabigh
# Abbreviations for days of the week

(Asked by: username_0 on 2015-06-27)

Is there a set of standard abbreviations for the days of the week for use in astronomy? I couldn't find any reference to it in the [The IAU Style Manual (1989)](http://www.iau.org/static/publications/stylemanual1989.pdf).

**Tags:** standards
> **Comments:**
> **username_1**: I'd be surprised if there was any set standard convention. The day of the week by itself has no use in astronomy unless you also know the corresponding calendar date. And since the day of the week is computable from the calendar date, it's really just superfluous information. Nevertheless, most astronomy apps such as Sky Safari seem to use the first three letters abbreviating the names for the days of the week, so you're probably safe going with that.  
> **username_0**: In English @barrycarter :-p  

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## 2 answers

### Answer by username_2 on 2017-03-17. Score: 1

[Wikipedia uses](https://en.m.wikipedia.org/wiki/Template:WEEKDAYNAME): mon, tue, wed, thu, sat, sun.

[ISO 8601](https://en.wikipedia.org/wiki/ISO_week_date) defines an exchange standard for dates based on weeks and days, which looks like this: 2017-W01-3 or this 2017W011 (Year, ISO week number, number of day of week starting with Monday). Not so surprisingly it does not standardize names of days as far as I can tell.

So you could claim to use ISO-8601 conventions and simply use 1-7 (starting with Monday).

A comprehensive listing of abbreviations of day names for European countries is given by the European Medicines Agency for [blistered drugs](http://www.ema.europa.eu/docs/en_GB/document_library/Other/2012/04/WC500124995.pdf) for the curious.


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### Answer by username_3 on 2017-01-15. Score: 0

*comments converted to community wiki*

The day of the week by itself has no use in astronomy unless you also know the corresponding calendar date. And since the day of the week is computable from the calendar date, it's really just superfluous information. Nevertheless, most astronomy apps such as Sky Safari seem to use the first three letters (in English) abbreviating the names for the days of the week. This use seems to conform with the [ISO week date standard](https://en.wikipedia.org/wiki/ISO_week_date).

> **Comments:**
> **username_4**: The week does represent one quarter of the Moon's phases, and the days are named after the five classical planets, the Moon and the Sun.  
> **username_5**: …except Saturday in all Nordic languages, where it means "washing-day".  
> **username_6**: Other languages also diverge in some cases; e.g. Italian uses _sabato_ (Sabbath) and _domenica_ (day “of the Lord”) for Saturday and Sunday, respectively, and German uses _Mittwoch_ (“middle of the week”) for Wednesday.  

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