Differences between weekNumber in Mongo and Luxon - mongodb

Question

I am doing some mongo aggregations on dates and have run in to an interesting problem, namely that the $week returned from mongo is different than the weekNumber returned from Luxon.
In the below code snippets, the $week from mongo returns 47, whereas the weekNumber from Luxon returns 48.
Is there a way to normalize the two so that a given date will return the same $week/weekNumber?
I can subtract one from the value returned by Luxon, but I'd like to understand why the responses are different in order to determine if there is a more appropriate/elegant way to fix this.
MONGO:
[{
'$match': {
'date': {
'$eq': datetime(2020, 11, 23, 0, 0, 0, tzinfo=timezone.utc)
}
}
}, {
'$project': {
'w': {
'$week': '$date'
}
}
}]
LUXON:
import { DateTime } from "luxon";
var week = DateTime.fromJSDate(new Date(2020,10,23)).weekNumber;
console.log(week);

Answer 1

Have a look at documentation:
weekNumber:
Week calendar: For ISO week calendar attributes, see the weekYear, weekNumber, and weekday accessors.
$week:
Returns the week of the year for a date as a number between 0 and 53.
Weeks begin on Sundays, and week 1 begins with the first Sunday of the year. Days preceding the first Sunday of the year are in week 0. This behavior is the same as the “%U” operator to the strftime standard library function.
If you like to get to Week number according to ISO-8601 use $isoWeek():
Returns the week number in ISO 8601 format, ranging from 1 to 53. Week numbers start at 1 with the week (Monday through Sunday) that contains the year’s first Thursday.
Looks like in Luxon does not have an equivalent to MongoDB's $week