General Astronomical References

• The STScI Digitized Sky Survey - This is the definitive source of digitized images.
• CDS, Strasbourg - Check here for the major European galactic databases.
• NED - You can get virtually all published information on any extragalactic object.
• The NASA Astrophysics Data System Home Page - Go here for online journal articles and abstracts.
• Astronomical Headlines - IAU keeps its major announcements here.
• Astronomical Data Center - Look here for galaxy catalogs such as RC3 and PGC.

Supernovae

• Bright Supernovae - Beautifully  maintained list of ALL supernovae discovered with images.
• High Redshift Supernova Search - Fascinating use of distant supernovae to determine the Hubble Constant.
• The BAIT Home Page - The original automated supernovae search system. Now includes KAIT.
• International Supernovae Network - Excellent overview of all amateur discoveries.
• List of Supernovae - IAU complete list of all supernovae ever discovered.
• List of Recent Supernovae - IAU maintains this up-to-date list of supernovae.
• Sternberg Astronomical Institute - Source of one of the two most complete supernovae catalogs.
• Omega Group, Extragalactic Supernovae Search - Excellent page showing a Sicilian group's work.

• SkyMorph - Searches on NEAT archival images and Digitized Sky Survey plates.
• DANEOPS Project - NEO pre-discoveries on photographic plates.
• Minor Planet Center (MPC) - Ephemeris and orbital elements for asteroids and comets, and several other web services for observers.
• NEO Confirmation Page - Ephemeris for newly discovered NEO candidates.
• JPL's HORIZONS System - Highly accurate ephemeris for most known solar system bodies, including some space probes.
• Near Earth Objects Dynamic Site (NEODyS) - Ephemeris, orbits, astrometric observations, and close planetary encounter information for all known NEOs.
• Asteroids Dynamic Site (AstDyS) - Ephemeris, orbits, and astrometric observations for a large fraction of the known asteroids.
• Asteroid Data Services By Lowell Observatory - A variety of useful web services for asteroid observers, from ephemeris to sky survey coverage.
• NASA Near-Earth Object Program - Includes a nice NEO orbit visualization applet and an up-to-date NEO collision risk page.
• European Asteroid Research Node - Lists of asteroids in need of photometric observation, and references to published studies on asteroid physical properties.
• Minor Planet Groups and Families - Definition of minor planet groups and families in terms of their orbital elements.
• Comet information and the International Comet Quarterly - Comet ephemeris, orbits, and recent magnitude estimates.
• LINEAR Project - The most productive among the current NEO surveys.