John Herschel discovered NGC 6559 = h1996 = h3733 on 1 Jul 1826 and recorded "several stars affected with nebulosity; the brightest taken." His position corresponds with a mag 8.8 star (brighter of pair) clearly involved with nebulosity. The CGH catalogue lists a similar position and notes "vF; L; oblong; 5' long; 3' broad; place of a D* involved; 6 other st near. Query, if involved."

300/350mm - 13" (7/16/82): fairly faint, curved strip of nebulosity, includes five stars.

400/500mm - 17.5" (7/20/96): at 140x an irregular glow is easily visible surrounding a group of 5 stars and brightest around a 30" pair of mag 9.5/10.5 stars. The 4'x3' nebulosity extends mainly to the west and NW of this pair. Best view probably unfiltered at 140x (nebulosity dims with OIII and similar with UHC), but with a UHC filter a very large hazy nebulosity ~10' diameter stands out to the northwest involving a number of brighter stars.

17.5" (7/17/93): observation made at 100x using an OIII filter: Brightest portion of extensive nebulous complex, most prominent along two converging rows of stars oriented SW-NE and NW-SE. A mag 10 star is located in the second chain. This description appears to describe the large region of nebulosity to the NW of NGC 6559 mentioned in the July '96 observation.

17.5" (6/20/87): 88x with UHC filter: fairly bright, fairly large nebulosity about 5' diameter. Surrounds two mag 11 stars and extending to four or five fainter mag 12/13 stars.

Notes by Steve Gottlieb