William Herschel discovered NGC 2420 = H VI-1 = h458 on 19 Nov 1783 (very early sweep and 4th object discovered) and recorded "a beautiful cluster of many large and compressed small stars, about 12' diameter." On 10 Feb 1787 (sweep 697) he noted "A brilliant rich cluster of stars." On 24 Feb 1827 (sweep 59), John Herschel called it "a p rich cl; irreg fig; 50...100 stars; 11...18m; 5..7' diam."

400/500mm - 17.5" (1/23/93): excellent cluster of at least 50 stars mag 11-15 within a 6' diameter. Good spread of magnitudes, includes 15 stars mag 11-13 over a rich background of numerous mag 14-15 stars and unresolved haze. The brightest mag 10 star is on the west side and has a mag 13 companion 12" S. Located between mag 9.1 SAO 79575 6' NNE and mag 8.9 SAO 79563 6' SSW. A faint galaxy pair, CGCG 117-059 and CGCG 117-060 (separation is just 40"), is in the field 10' WNW! Both of these are extremely faint and small.

Notes by Steve Gottlieb