Supreme Court Justice Ruth Bader Ginsburg on Monday attended a concert called, "Notorious RBG in Song" in Washington, D.C., marking her first public appearance since undergoing lung cancer surgery last December.

The 85-year-old has been recuperating at her home in Washington since the procedure at New York's Memorial Sloan Kettering to remove the lower lobe of her left lung. Two nodules were discovered in a CT scan shortly after she broke ribs in a fall. She had two previous bouts with cancer, but doctors are optimistic that the surgery was successful and she is cancer free.

The justice sat in the back of the darkened auditorium at the National Museum of Women in the Arts and, according to The Washington Post, was only spotted by concertgoers as they left the performance.

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The concert was presented by her daughter-in-law and other musicians. Patrice Michaels is married to Ginsburg’s son, James. Michaels is a soprano and composer. James Ginsburg said before the concert that his mother is walking a mile a day and meeting with her personal trainer twice a week.

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Ginsburg’s recent absence from the court and participation from home is not unprecedented. The late Chief Justice William Rehnquist also worked from home and even authored several opinions while undergoing cancer treatment from 2004-05.

The Associated Press contributed to this report