Deep Sky Observing
- Deep sky object types and classifications. Includes a Messier interactive map, pictures, constellations and observation guide.
- http://www.deepskyobserving.com

Deepsky Observer's Companion
- Tutorials, chart index, discussions, certificates, and resources.
- http://www.psychohistorian.org/astronomy/doctutorial.html

Secrets of Deep-Sky Observing
- Pointers observers should know includes sky brightness, dark adaptation, averted vision, high power, capturing color, and other tips.
- http://skytonight.com/observing/objects/deepsky/3304001.html

Deep Sky Intro
- Article on various types of deep sky objects.
- http://www.nightskyinfo.com/deep_sky_intro/

Iiro's DeepSky Sketches
- General information, astronomical pictures, sketches, observation reports, objects, and telescope information.
- http://kotisivu.mtv3.fi/deepsky/

The Searchable Universe
- Celestial object catalogs providing links to information.
- http://www.altairfour.net/SU/

Visual Deep Sky Observing
- Galleries of sketches, legend, projects, publications, and links.
- http://www.andreas-domenico.de

NetAstro Catalog
- The Internet Amateur Astronomers Catalog (IAAC), a mailing list for deep sky observers of all levels.
- http://www.visualdeepsky.org

The National Deep Sky Observers Society
- Contains information, challenges, galaxy clusters, globular clusters, open star clusters, naked eye observations, observing planetary nebulae, the Milky Way, and star hopping.
- http://www.cismall.com/deepsky/

A CCD Tour of the Universe
- Includes deep sky objects and solar system CCD galleries, techniques and resources, and equipment.
- http://astrosurf.com/jwisn/

Messier Marathon
- Includes instructions, biography, dates, timeline, posters, NASA tv, and links and information.
- http://www.messiermarathon.com

View-tah's Astronomy Pages - Deep Sky
- Information, images, charts for the Messier, Caldwell, NGC, and Hubble with search tool.
- http://www.utahskies.org/deepsky/

Deep Sky Collections and Catalogs
- Links and observing lists.
- http://seds.lpl.arizona.edu/messier/xtra/similar/catalogs.html

Messier45
- Observing guide, articles, Messier Gallery, Herschel 400 and Deep Sky Browser which lets you search deep sky objects and view maps and images of over 600,000 objects.
- http://messier45.com/

Deep Sky - Sketching and Observing
- Gallery of sketches, links, and sketches upload area..
- http://www.skyrover.net/ds/

Ian's Astro Page
- Sketches, scratchings, pictures, and links, and construction of piggyback camera adaptor.
- http://www.nabu.net/astro/

The Messier Catalog
- Images and galleries, marathoner list, and new nebula and supernovae.
- http://www.seds.org/messier/

The NGC/IC Project
- An attempt to correctly identify all the original objects, starting with the original discoverer's notes and working forward in time to encompass the work of contemporary astronomers, both professional and amateur.
- http://www.ngcic.org/

List of Common Deep Sky Catalogs
- General, supernova remnants, planetary nebulae, diffuse nebulae, dark nebulae, open clusters, globular clusters, galaxies, clusters of galaxies, double stars, and references.
- http://www.seds.org/messier/xtra/supp/cats.html