A complete listing of the great many astronomy-related websites useful to observers is far beyond the scope of this page. What follows is a selection of those we've found most useful. For a much more comprehensive listing, we suggest the AstroWeb, a database of astronomy links maintained by the AstroWeb Consortium.
(Weather links are listed separately.)

LITERATURE, CATALOGS, DATA, SURVEYS, TOOLS

Astronomical Almanac
VizieR
SIMBAD, France
SIMBAD, Harvard
NASA Space Science
Data Coordinated Archive

ADS Abstract Service
ADS Article Service
DSS, STScI interface
DSS, CADC interface
NED
Ephemeris Generator
UCSC Science Library

UNIVERSITY of CALIFORNIA ASTRONOMYTOP

Center for Adaptive Optics at UCSC
LLNL Astrophysics
LLNL Laser Guide Star/Adaptive Optics
UCB Astronomy
UCB Space Sciences Laboratory
UCI Physics and Astronomy
UCR Physics and Astronomy
UCLA Division of Astronomy and Astrophysics
UCLA Infrared Imaging Detector Laboratory
UCO / Lick Observatory
UCSB Dept. of Physics
UCSC Dept. of Astronomy and Astrophysics
UCSD Center of Astrophysics & Space Sciences
UCM Physic and Astronomy

Institutes of Geophysics and Planetary Physics (IGPP's): UCLA | UCSC | UCSD | UCR

OBSERVATORIESTOP

AAO
Armagh
Apache Point
Calar Alto
CFHT
Chabot
DAO
DRAO
ESO: La Silla
ESO: Paranal
Galileo
Gemini
Griffith
HST
Isaac Newton Grp.
Keck
Las Campanas
Lick
Lowell
Mauna Kea
McDonald
Mount Graham
Mount Wilson
MMT
NOAO: CTIO
NOAO: KPNO
NRAO
Palomar
Subaru
UKIRT
Yerkes

OTHER ASTRONOMY LINKSTOP

AAS
ARENA
AURA
ASP
Caltech Astronomy
Canadian Astronomy Data Centre
CfA
Challenger Center
ESA
ESO
Herzberg Institute
IAU
IDA
IPAC
MIRA
NASA
NASA Goddard
NOAO
NSF
SEDS
SETI
Sloan Digital Sky Survey
STScI