M16, the Eagle Nebula, is named for its
resemblance to the outstretched wings of an eagle. M16 actually refers to the open
cluster NGC 6611; the associated nebulosity is IC 4703. The cluster is 5.5 million
years old and is located at a distance of 7,000 light-years. Both M16 and M17 are
visible to the naked eye in a dark sky. M18 is the relatively small cluster to the
right of M17 in this image. Estimates of its distance range from 3,900 to 6,000
light-years.
Equipment: Nikkor
180mm/2.8 lens/ST-10XME/Astrondon LRGB filters/Paramount ME
F-ratio: f/4
Exposures: RRGB: R 12 x 8 minutes: G 10 x 2 minutes: B 10 x 2 minutes: GB
binned 2x2
Date: August 3-4, 2007
Location: Landers, California, USA
Technical Notes: Individual
exposures were sigma combined. The RGB
image was created in Registar 1.0. A Gaussian Blur of 1 pixel was applied to the RGB
image. The red data were used as the luminance image and a High Pass Filter of 4 pixels
was selectively applied to it using a Layer Mask. An RRGB image was created with the
luminance image set to an Opacity of 50%. This image was then flattened and then combined
again with the luminance image set to an Opacity of 100%. A duplicate of the RGB image was
combined using Soft Light to increase color saturation.
