Deep-Sky Challenge

About the Deep-Sky Challenge List

The DSC list, compiled by Alan Dyer and Alister Ling complements the Finest NGC list, as there is no overlap. The list features "fringe" deep-sky treasures that are somewhat more challenging objects than what most observers look for. The attraction of observing is not the sight of an object itself but the intellectual contact with what it is.

Here is an overview of the DSC Observing List:

Deep-Sky Challenge Objects Number Notes
Open Clusters   2 NGC 609 in Cassiopeia and NGC 6791 in Lyra.
Globular Clusters   4 Includes Palomar 11 in Aquila.
Emission/Reflection Nebulae   13 Includes California Nebula in Perseus and Barnard's Loop in Orion.
Dark  Nebulae   2 Includes B33, the Horsehead, and B72, the Snake.
Planetary Nebulae   8 Includes Jones 1 in Pegasus.
Supernova Remnants   1  
Galaxies / Galaxy Clusters / Quasars   15  
Total 45  

RASC Deep-Sky Challenge Certificate

The DSC Certificate has been awarded since 2008. Observing the DSC list is an excellent project for those who have completed their Finest NGC and/or Messier Certificate and who are looking for a challenging observing program. The official list can be found in the RASC Observer's Handbook. At least a 30-cm (12-inch) telescope is recommended to complete most of the list, although it can be accomplished with a 25-cm (10-inch) under good skies. A few of the objects will require access to a large telescope (50-cm / 20-inch). Several DSC objects can be observed in even smaller instruments, so these could be used to get started on the brighter objects. With all instruments, a nebular filter will be necessary to see the often visually faint glowing clouds of gas and dust of some objects.

In the case of galaxy clusters, try to identify as many individual galaxies as you can, but also look for the collective background glow of the others at the edge of perception.

The DSC observing program can be started during any season. You must be a member in good standing of the RASC to be awarded this certificate. An application form can be found from a link at the bottom of this page.

Contact the Observing Committee chair


Here are some recommended resources to help you tackle the DSC Certificate program:

  • Uranometria - by Wil Tiron is adequate for most objects
  • Tri-Atlas - by Jose Torres and Casey Skelton, free downloadable PDF charts contain all objects.
  • Earth Centered Universe - by Dave Lane — useful PC Software.
  • The Night Sky Observer's Guide (Volumes One and Two) - by George Robert Kepple and Glen W. Sanner, contains descriptions and finder charts for many of the objects on the challenge list.
Last modified: 
Saturday, August 4, 2018 - 8:50am