Meryl Streep in Hollywood last year. (Rich Schmitt/AFP/Getty Images)

Updated 7 p.m.

Staffers were all abuzz Tuesday about glimpsing Meryl Streep on the Hill. But what brought La Streep to town? No scheduled celebvocacy events, and her Kennedy Center Honor is still several weeks away.

We found a clue in a mysterious paparazzi-like photo that popped up on a Meryl fan site. There she was, surrounded by several other women who were somewhat familiar themselves. . .

We’re told the occasion was an Annie Leibovitz photo shoot for Vogue. Streep is once again the subject of awards buzz (for her turn as Margaret Thatcher in the forthcoming “The Iron Lady”); but when asked by the magazine to pose for a feature, she suggested turning the focus to a favorite cause -- the National Women’s History Museum, which after years of fundraising and planning is still seeking a home on the Mall.

Sources on the scene tell us that Streep enlisted some glass-ceiling shatterers and prominent supporters of the museum to co-star with her in the photo shoot: Madeleine Albright, Sen. Barbara Mikulski, Sen. Susan Collins, Del. Eleanor Holmes Norton, Rep. Carolyn Maloney, Tricia Nixon Cox, the younger Barbara Bush, and NWHM President Joan Wages. The group posed at the west lawn of the Capitol, near the House side; and on the Capitol’s east steps, closer to the Senate side.

Updated, 7 p.m.: We asked Del. Norton, who co-sponsored the bill to authorize the museum, about her photo shoot experience. Leibovitz “is a quick study and quick shoot,”she told us Wednesday. “She said, ‘Get up there and start talking’ ” — so they all brainstormed about how to get the museum’s authorization through Congress.

Correction: An earlier version of this story referred to Wages as the NWHM’s founder. She was a founding board member and is now president.

Read earlier: Meryl Streep speaks out for National Women’s History Museum, 8/23/10