Wow! So cool to see this on HN. I visited the observatory last time I was in Samarkand. Apparently their calculation of a year was pretty accurate even in the 15th century.

The article is illustrated with a photo of a meridian, but it’s not mentioned in the piece.

I dont understand how it worked. It does not mention any telescope but does mention largest "quadrant principle device" with not further explanation on what this is and how it worked.

The observatory predates the invention of refracting telescopes. It was used to determine the position and movement of stars and planets, not to observe them. The "quadrant" is a device to accurately measure the angle of an observation:

https://en.m.wikipedia.org/wiki/Quadrant_(instrument)

It's essentially a very big 'protactor' used to measure angles (of stars or the sun over the horizon). The bigger such a device is, the more accurate the measurements.

Oddly, the article on Ulithi Beg himself has a better description of how the observatory works

https://en.m.wikipedia.org/wiki/Ulugh_Beg

This is a pretty terrible wikipedia page. A number of grammatical errors and some really questionable citations, as well as a writing style similar to a high school student padding out an essay for history class.

Since you're on HN anyway, you could spend 5 minutes improving it :)

I was disappointed not to see a tastefully done image of Hoki on the page

    https://en.wikipedia.org/wiki/Hoki_(fish)

I never knew this is the fish McDonald's has in their fillet-o-fish.

This is why I like HN. It's supposed to be about hacking, but sometimes you can just see it's a community of deeply curious people with all sorts of intellectual interests.

When wikipedia articles are posted, this becomes particularly evident, because it's not a news article, which tries to convince you why this is interesting: it's just the plain and simple wonder of discovering something exists.

There is a cut-away diagram of the observatory about 2/3 of the way down this page: https://mindofahitchhiker.com/ulugh-beg-observatory-samarkan.... You can see that the main feature was the quadrant hallway: a narrow vertical open space with a window set at a top corner and quarter-circle measurement track rising from the below-ground levels up the back wall of the building, as in this cut-away ascii art:

      /window
      xxxxxxxxxxxx
    x           |x
    x           |x
    x           /x
    x          /xx
    x         /x x
    x       - xxxx 
    x    --xx xx x
    x---xxxxxxxxxx

then an observer on bottom can measure the angle of elevation to a star visible in the window. As the planet rotates a different slice of the sky can be observed over the course of the night, allowing careful measurements of a large portion of the visible sky.