Isaac Roberts found IC 4703, the nebulosity involved in M16, on a photograph taken with his 20" reflector in 1894. Although De Chéseaux discovered M16 between 1745-46, he only mentioned a star cluster and even William Herschel just described the stars using his 12-inch reflector: "Large stars with small ones among them; within a small compass I counted more than 50, and there must be at least 100 without taking a number of straggling ones, everywhere dispersed in the neighborhood."

Although Roberts is credited with the discovery in the IC, Wolfgang Steinicke notes in his book on the history of the NGC that Etienne Trouvelot made a visual discovery in 1876 with the USNO 26-inch refractor. Trouvelot mentioned "..described by Sir J. Herschel as a loose cluster of at least 100 stars, I have found to be involved in an extensive, although not very bright, nebula, which seems to have escaped his scrutiny. In a study and drawing of this nebula made in 1876, its general form is that of an open fan, with the exception that handle is wanting, with deeply indented branches on the preceding side, where the brightest stars of the cluster are grouped. From this peculiar form, this object might be appropriately be called the Fan Nebula."

Independently, Robert Innes, observing in 1914 at the Union Observatory in Johannesburg, reported "with the 9-inch refractor the nebula is just visible and it fills the perimeter of the cluster with faint extensions beyond."

300/350mm - 13.1" (8/17/85): a thin dark "finger" extends towards the cluster, positioned just south and beyond the two bright mag 9 stars near the center. This is an extension of the wider projection seen previously several times and which is better defined along the south edge.

13.1" (8/15/82): the "Eagle Nebula" is a fairly bright 30' nebulosity in a striking outstretched eagle shape with a bright scattered cluster superimposed. There is a considerable contrast gain to the nebulosity using a UHC or OIII filter. With a UHC filter, a dark projection (called the "Star Queen") enters on the southeast edge of the nebula and extends inward to the west. The cluster members surrounding the "head" of the eagle include ten mag 8-10 stars and a bright pair of mag 8.5 stars (8.2/8.8 at 27"). A dark triangular wedge is visible off the north side.

13.1" (5/26/84): the dark protrusion was fairly easy at 88x.

Notes by Steve Gottlieb