NGC 2169: A “37” Tattooed on Orion’s Outstretched Arm

High above Orion’s Nebula and belt lies the star cluster NGC 2169, affectionately known as the “37 Cluster.” This arrangement of stars earned its nickname due to its resemblance to the number 37 when viewed through a small telescope or binoculars. Depending on how you view it, it may also resemble the letters “LE.”

As open clusters go, NGC 2169 is relatively small as it only spans 7 light years and takes up about 5 arcseconds of the sky. For comparison, the full moon takes about 1800 arcseconds in the sky. The cluster lies roughly 3,600 lightyears away from us.¹ The Italian astronomer Giovanni Battista Hodierna may have discovered this unique congregation of stars in the 1600s, but we know the renowned astronomer William Herschel first recorded the object on October 15, 1784. As I write in my observation notes below, it’s a must-see attraction on winter nights.

My Observations

As I sketch this cluster on this winter’s night, this object is becoming one of my favorites. I wish I could see even more detail, but the rising full moon is washing out the sky with each minute. It looks like a pair of butterfly wings in my eyepiece as if a butterfly is swirling around the Hunter’s head as he treks across the sky. Several prominent brighter stars with varying colors create the pattern, making the object even more attractive.

As I write this entry, I’ve discovered the cluster looks like a “37.” Pretty cool. In fact, I didn’t notice it until I processed my Seestar image from the same night (below). There, amongst a sea of stars, I see 37 tattooed on the Hunter’s raised arm!

Key Stats

Sources and Notes

Banner photo: By ScottRak – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7727924

¹Garboni, N. (2005, November 18). APOD: 2005 November 18 – The 37 Cluster. Apod.nasa.gov. https://apod.nasa.gov/apod/ap051118.html

Sketch and Seestar image by Wayne McGraw