Professor Werner Sumowski has kindly confirmed the attribution to Philips Koninck in a letter dated 28 November 2003. Professor Sumowski suggests that the drawing dates from early in Koninck's career, perhaps from the second half of the 1640s. The drawing can be compared to a landscape in watercolor in collection of Frits at the Fondation Custodia, Paris (W. Sumowski, Drawings of the Rembrandt School, New York, 1982, VI, no. 1482x), although Professor Sumowski notes that because of the watercolor on the Paris landscape it appears to be less linear than the present drawing.
Another panoramic landscape drawing by Koninck, from the Dr. and Mrs Rudolf J. Heinemann Collection, was sold at Christie's London, 1 July 1997, lot 211, and was exhibited at the Pierpont Morgan Library, New York, The Thaw Collection: Master Drawings and oil sketches, Acquisitions since 1994, 27 September 2002-19 January 2003, no. 7.