After completing my Messier Catalog poster and my Top 100 Astrophotography Objects poster, I decided to image a poster of the Caldwell Catalog. The Caldwell Catalog is a list of 109 sky objects published by Patrick Moore in 1995 as a complement to the Messier Catalog. The Messier Catalog was developed as a list of objects to avoid when looking for comets, not as a list of the best objects in the sky to observe. Messier did not include many of the sky's brightest deep-sky objects, and only included objects he could see from Paris. The Caldwell Catalog covers the entire sky and includes interesting objects which are not on Messier's list. Both of these lists were compiled for visual use, but both are also convenient lists for astrophotographers.

The Caldwell objects are numbered from 1 thru 109 in order from northernmost to southernmost objects, spanning from +85 to -80 degrees declination. Of course, unless you live near the equator, you are not able to see all of the Caldwell objects from one site. For this poster, I am only including those objects which I can see from my backyard in East Texas, which includes 85 of the 109 Caldwell objects. The higher numbered Caldwell objects are difficult to image clearly from the northern hemisphere because of their low altitude. For example, Caldwell 85 transits a maximum of only 6 degrees above my southern horizon. I also have included 2 images here which describe the catalog in tabular form, including location, size, object type, and nickname.

After imaging both lists, it is interesting to compare the Caldwell list versus the Messier list. In my opinion, the Caldwell list is underrated. If I had to choose only one list to image, it would be a tough choice. Compared to the Messier list, the Caldwell list has about the same number of open star clusters (C-28, M-27) and galaxies (C-35, M-39), but the Caldwell list has less globular clusters (C-18, M-28) and many more nebula (C-28, M-12). Looking back on my Top 100 poster, I ended up selecting about the same number of objects from each list (C-28, M-25). Messier has the more famous objects (highlighted by the Orion Nebula, Crab Nebula, Andromeda Galaxy, Hercules Cluster, Ring Nebula, Eagle Nebula, Pleiades, Whirlpool Galaxy, and Dumbbell Nebula), while the Caldwell list has more nebula, more small scale objects, and more variety of objects (highlighted by the Rosette Nebula, Helix Nebula, Crescent Nebula, Omega Centauri Cluster, Bubble Nebula, Antennae Galaxies, Witch's Broom Nebula, Eastern Veil Nebula, and Centaurus A Galaxy). The entire Messier list is accessible from the Northern Hemisphere, which is a big factor if you live there. However, the Messier list includes more than a few clunker astrophotography objects (e.g., double star, Andromeda satellites, dim clusters) and feels somewhat repetitive as one moves through all of the clusters. The Caldwell list also includes a few less than spectacular objects, but doesn't feel quite as repetitive.

For both lists, the image scales dictated that I use primarily my longer focal length (130 mm) scope. I only used the shorter length scope (85 mm) for a few objects on each list (C-4, M-7).

The image is high resolution - 16000 x 10667. This allows the ability to see each object in detail and to print out the poster, but it takes some time for Astrobin to load the full resolution version of the image. Each Caldwell object image is also posted individually on this Astrobin site, along with a description of the object.

For more detailed information on each of these objects, please see my Astrobin Caldwell Object Collection.

I have also created a sortable spreadsheet that contains key information for all of the over 400 objects from my 4 main Astrobin compilations (Messier, Caldwell, Hidden Treasures and Secret Deep). The spreadsheet data for each object includes designation, nickname, object type, RA & Dec, transit date, and size. If you would like a free copy, please email me at [email protected]