Loughran’s small and large crosses are probably intended as stars. The lower number of small devices may result from the illustration’s size. Nantucket Signals gives no flag date.
Indus operated from Nantucket in 1816–1824, then was broken up. George Barrett was the first owner; later entries include Thadius ? and unidentified owners. T. Starbuck & Co. and Val. Hussey & Brothers acted as agents.
Keep the explicit scope label independent; no alias or company identity is inferred.