I got to see Bobby leave the nest but did not see if he had been in the nest for a visit or had had a proper nest switch with Sadie.
He circled above most of the park. I lost sight of him when he was at the eastern side of the park.
Roughly 15 minutes later, a Peregrine Falcon flew to the eastern side of Washington Square Park and tried to catch a pigeon but missed. It then returned from where it came from (south of the park):
Bobby then reappeared and landed on NYU's Silver Center (which overlooks the eastern side of the park):
Bobby circled above then dove like a shot northeast from the park.
I watched Sadie rotate the eggs several minutes later:
A fellow Hawk-watcher and I went to look for Bobby.
I found him on top of the ConEd building, a usual spot (I've seen him perching there from time to time since 2011):
He hopped off the tower 15 minutes after I had spotted him but he might have been on that perch for as long as an hour (since I saw him dart in the tower's direction earlier).
He landed on a railing perch I'd never seen him on before:
He was sitting above 11th Street between 3rd and 2nd Avenues.
The following Google Maps screen shots should put his perches in perspective.
Washington Square Park is in the lower left, the ConEd tower at the upper right (the first building you see after the words "E 14th St"), and his railing perch was on the building at the lower right (seen between the place-names "The Smith" and "AMC Loews Village 7"):
Closeup of his railing perch atop the building:
He left his perch after 6 minutes.
I had to attend to an errand but was pleased to see him fly back toward the park when I headed home.