P505 is described as a second flag. Nantucket Signals shows a longer blue tail, deliberately shortened in Rosanoski’s rendering.
The source also records P151 in the signal painting.
Peru operated from Nantucket in 1818–1863, then was sold to New London. Named owners include Obed Coffin, Thomas Macy, David Joy, David Thane, William R. Easton and Zenas L. Adams. Agents included David Joy Jr., David Joy, Robert F. Gorham, David Thane and Zenas L. Adams.
Keep the explicit scope label independent; no alias or company identity is inferred.