Caldwell Objects (C)

Caldwell (C): (1995) Compiled by Sir Patrick Moore a legendary British amateur astronomer and broadcaster, as a supplement to Messier. Contains 109 beautiful objects that Messier omitted (often because they were too far south). It was published in December 1995 in Sky & Telescope magazine.

The Caldwell catalogue is essentially the modern sibling of the Messier list. It was created to solve the two biggest complaints about Messier: that he missed many of the sky's best objects and that he ignored everything in the southern hemisphere.

Here is the breakdown of the Caldwell objects:

1. The Origin: A Modern Complement

Moore noticed that while the Messier list was popular, it was never meant to be a best of list. It was just a list of things that weren't comets. Because Messier lived in Paris, he also couldn't see anything far to the south. Moore wanted to provide a more inclusive and visually stunning alternative for backyard observers.

2. The Name: Why Caldwell?

You might wonder why it is not called the Moore Catalogue. Since the letter M was already used for Messier, Moore used his other surname, Caldwell (his full name was Patrick Caldwell-Moore). This allowed him to use the prefix C for all objects in the list.

3. What is in the Database?

Just like Messier, this list contains 109 objects. This number was chosen specifically to match the common count of the Messier list at that time.

The contents include:

• 35 Galaxies

• 18 Globular Clusters

• 25 Open Star Clusters

• 13 Planetary Nebulae

• 18 Other Nebulae and Supernova Remnants

4. Key Differences from Messier

• Global Reach: While Messier is limited to the northern sky, the Caldwell objects are spread from the north pole to the south pole.

• Organization: Unlike Messier, which is numbered in the order of discovery, the Caldwell list is organized by Declination (latitude in the sky). C1 is the northernmost object, and C109 is the southernmost.

• Visual Appeal: Moore intentionally included spectacular objects Messier missed, like the Double Cluster in Perseus or the Omega Centauri globular cluster.

5. Famous Caldwell Objects to Find in Stellarium

The Caldwell objects are often considered the second step for amateur astronomers. Once you have seen the Messier objects, the Caldwell list provides the next level of challenge and beauty.

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