Here on Astrobin I have previously published compilation posters of 3 popularly recognized deep sky object catalogs:

1. The catalog of 110 Messier objects, established in the 1700s by Messier.
2. The catalog of 109 Caldwell objects, published in 1995 by Caldwell.
3. The catalog of 109 Hidden Treasures objects, published in 2007 by O’Meara.

In total, these 3 catalogs contain 328 of the most interesting objects in the heavens, enough to satisfy most avid amateur astronomers over their lifetime.

But what if you are looking for more objects to view or image? In 2011, astronomer Stephen James O'Meara published a catalog of 109 objects called the Secret Deep, documented in his excellent book entitled Deep-Sky Companions: The Secret Deep. This list contains 109 interesting deep sky objects which are not already included in the three above catalogs. All are visible through a 5-inch telescope under dark skies.

To think of these Secret Deep objects as the 329th to 437th "best" sky objects in the sky would be inappropriate in my opinion. I consider some of these objects, such as Thor's Helmet, to be among the very best objects that the sky has to offer. The list consists of 23 open star clusters, 38 galaxies, 11 globular star clusters, 15 bright nebulae, 18 planetary nebulae, 1 asterism, 1 supernova remnant, 1 quasar and 1 black hole.

At 498 pages, the book contains an average of 5 pages per object, including maps, finder charts, images, illustrations, scientific information and interesting stories. This book is well written and is a great addition for anyone who enjoys viewing the night sky. The book photos are monochromatic and I don’t feel they capture the beauty and appearance of these wonderful objects. Over the past few years, from my location in Onalaska, Texas at 31 degrees north latitude, I have imaged 107 of these 109 objects. I did not image the quasar (#59) or the black hole (#93), since there is not much to see visually for these 2 stellar objects.

The result is contained on this high resolution poster, which is best seen when viewed in full resolution. The 107 objects are sorted in order of right ascension, starting with SD1. The object size range is broad, from 0.1 to 140 arc-minutes. I also have included 2 images here which describe the catalog in tabular form, including location, size, object type, and nickname. For more detailed information on each of these objects, please see my Astrobin Secret Deep Collection.

I have also created a sortable spreadsheet that contains key information for all of the over 400 objects from the 4 compilations mentioned here. 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]

Please let me know if you have any questions or comments.