For the second time in three days, an artist caught the attention of New Yorkers with an illegal stunt over the East River.

Two days after a Brooklyn artist was arrested for piloting a homemade submarine toward the Queen Mary 2, a local artist who goes by the name of Judith Supine yesterday morning draped a 50-foot portrait of a neon green human-like figure from the Manhattan Bridge, according to the Gothamist Web site.

“It’s a very unique style,” the publisher of Gothamist, Jacob Dobkin, said.

Mr. Supine is a prolific street artist who hangs similar, though smaller, collages of brightly colored men and women in parts of Brooklyn and Lower Manhattan, Mr. Dobkin, who has met Mr. Supine, said. Yesterday’s was his highest-profile stunt, however, Mr. Dobkin added.

A photo sharing Web site, Flickr, has more than 200 photos of various pieces of street art attributed to Mr. Supine.

The green portrait, which had disappeared by late afternoon, appeared to draw less attention than Friday’s East River excursion by artist Duke Riley, who steered his replica of a wooden Revolutionary War-era submarine too close to the Queen Mary 2. Swarmed by police boats and a helicopter, Mr. Riley was issued summonses for reckless operation of a vehicle, police said.

While the two acts were probably not linked, some artists say attention-grabbing artistic demonstrations could be on the rise.

A co-founder of the DUMBO gallery Ad Hoc Art, Garrison Buxton, said restrictions on other forms of expression, such as a proposal that requires a permit for filmmaking and a perceived crackdown on graffiti, are pushing people to some of these demonstrations. “It’s kind of like the more they try and squash it, the more it will pop up in other ways,” Mr. Buxton said. The police said they had no information about the Manhattan Bridge art.