Loughran calls N549 a second flag. Nantucket Signals dates N550 to 1845 and N551 to 1837–1855. N627 comes from the 1840–1850 painting.
Nantucket, also called Nantucket II, operated in 1837–1859 and was lost in the latter year. H.G.O. Dunham owned her in 1850 and 1855 and acted as agent through 1850, followed by Perry & Dunham.
Keep the explicit scope label independent; no alias or company identity is inferred.