Caldwell 16 — Open Cluster in Lacerta
NGC 7243
About C16
Description
NGC 7243 is an open cluster in Lacerta, about 2,800 light-years away. It contains around 40 stars spread across 21 arcminutes, with a handful of brighter members at magnitude 8-9 forming distinctive chains and patterns.
Observing Tips
A loose, scattered cluster best seen in binoculars or a wide-field telescope at low power. The brightest stars are easy to resolve. Located in a relatively sparse part of the Milky Way. Best observed in autumn evenings.
History
Discovered by William Herschel in 1788. One of the less famous Herschel discoveries, but a pleasant target for sweeping the autumn Milky Way.
Fun Facts
NGC 7243 is estimated to be about 100 million years old. Its sparse appearance suggests it is gradually dispersing into the general stellar population of the Milky Way.
Observe
1Properties
Position & Identifiers
2How easy to spot?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Easy | Easy | Easy |
| 150 mm Newton 150mm Newt. | Easy | Easy | Easy |
| Celestron C8 (203 mm SCT) C8 203mm | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
3Visibility
Set a location in User Settings to see visibility data.
4
Eyepiece View
5
Best Magnification
6Where this cluster sits in time
Open clusters span more than four orders of magnitude in age — from newborn OB associations to ancient, metal-rich survivors.
7
Colour-Magnitude Diagram
A cluster's colour-magnitude diagram reveals its age: the bluer the turn-off point where the main sequence bends into red giants, the younger the cluster.
Each point is a Gaia-DR3 member. Colour encodes spectral type; size reflects membership probability.
Explore
8
Classification Decoder
Discover
9
Light Travel Time Machine
10
Relativistic Travel
Community Photos (1)
Credit: Egres73. License: CC BY-SA 3.0. (Wikimedia Commons)
Skybred Mar 2, 2026
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
Explore Nightbase
Related knowledge, tools, and stories — no observation planning required.
