The following organizations sponsor public observing and astronomy-related programs. All are located within a 2.5 hour drive from the foot of Mount Hamilton.

The Astronomical Association of Northern California

c/o Chabot Space & Science Center
10000 Skyline Boulevard
Oakland, CA 94619
phone: 510-336-7300
web: http://www.aanc-astronomy.org/

The Astronomy Connection (TAC)

phone: 408-356-1125
email: webmaster@observers.org
web: http://www.observers.org
star parties in a variety of locations, informational mailing list

Chabot Observatory

10000 Skyline Blvd, Oakland, CA 94619
phone: 510-336-7300
fax: 510-336-7491
web: http://www.chabotspace.org
youth and teacher programs, volunteer opportunities, planetarium and telescope viewing

Foothill College Observatory

12345 El Monte Road, Los Altos Hills, CA
phone: 650-949-7334
web: http://www.foothill.edu/ast/index.htm
night and solar observing, classes, lecture series

Fremont Peak Observatory Association

P.O. Box 787
San Juan Bautista, CA 95045
phone: 831-623-2465
email: info@fpoa.net
web: http://www.fpoa.net/

Morrison Planetarium

California Academy of Sciences
Golden Gate Park
San Francisco, CA 94118
phone: 415-750-7141
web: http://www.calacademy.org/planetarium
variety of planetarium shows, lecture series featuring prominent astronomers

San Francisco Amateur Astronomers (SFAA)

hotline: 415-566-2357
web: http://www.sfaa-astronomy.org/sfaa/
star parties in various locations

San Jose Astronomical Association (SJAA)

1840 Yosemite Drive
Milpitas, CA 95035
hotline: 408-559-1221
web: http://www.sjaa.net/sjaa.html
star parties, observing sessions, classes

Santa Cruz Astronomy Club

L-2 San Carlos Lane
Santa Cruz, CA 95065
phone: 831-335-2423
web: http://astro.santa-cruz.ca.us/
viewing nights, astronomy talks

Sonoma State University Observatory

1801 E. Cotati Ave
Rohnert Park, CA 94928
phone: 707-664-2267
web: http://phys-astro.sonoma.edu/observatory/
monthly public viewing nights
weekly public lecture series, “What Physicists Do,” which includes some astronomy lectures: http://phys-astro.sonoma.edu/wpd.