From the 365 Days of Astronomy Podcast on February 6:
"On Feb. 7, 1889 there was a triumphant meeting of a San Francisco club of amateur photographers to celebrate their successful "shooting" of a total eclipse of the Sun. At this gathering, a group of 40 astronomers, educators, and astronomy enthusiasts signed the Charter Membership Roll of a group they called the Astronomical Society of the Pacific. As we celebrate the International Year of Astronomy in 2009, we also commemorate the 120th anniversary of the founding of the ASP -- the first national (and international) astronomical organization in the U.S."
The ASP website also has some special features and articles this month commemorating this special anniversary.