Amateur
- 521
- Polaris Observatory Association
- Provides telescope and camera information, gallery, and astrophotography information.
- 522
- San Diego Astronomy Association
- Outreach, events, resources, merchandise, utilities, and telescope loaner utility page.
- 523
- San Francisco Amateur Astronomers
- Bulletin board, meetings, lectures, star parties, calendar, newsletter, and photography.
- 525
- San Jose Astronomical Association
- Star parties, lunar eclipse information, hints for beginners, star party etiquette, and activities.
- 526
- Santa Barbara Astronomical Unit
- Monthly events calendar, night sky, events, newsletter, archive, photo album, classifieds, and dark sky sites.
- 529
- Sonoma County Astronomical Society
- Calendar, events, activities, beginners information, and gallery located at Santa Rosa.
- 530
- Stockton Astronomical Society
- Activities, services, newsletter, astro-kid section, gallery, and links.
- 531
- The Antelope Valley Astronomy Club
- Calendar, observing and planetarium information, essay contest winners, and photos located at Lancaster.
- 532
- The Eastbay Astronomical Society
- Astro advice, constellation chronicles, newsletter, workshop, schedule, and gallery located in Oakland.
- 533
- Ventura County Astronomical Society
- Offering monthly meetings, equipment loan, events, monthly calendar of sky watching, and contacts located at Moorpark College.
- 535
- Arkansas Oklahoma Astronomical Society
- Gallery, forum, downloads, FAQ, news, articles, tips, and education outreach located in Fort Smith.
- 536
- Central Arkansas Astronomical Society
- Club and astro news, minutes, technical tips, and forum located northwest of Little Rock at the River Ridge Observatory.
- 537
- Red River Astronomy Club
- Star party information, directions, photos, meeting information, and news located near Nashville.
- 538
- Saguaro Astronomy Club
- In Phoenix, provides meeting schedules, newsletters, FAQ, gallery, observing notes, and downloads.