The Eagle Nebula and M16

m16-v2 and m16-v3

These add-ons for Celestia v1.3.0 (or later) display a montage of six images of the Eagle Nebula and its associated galactic cluster, M16. They also include an STC file defining 74 of the stars in the cluster. (Some of these star definitions specify star names, which requires Celestia v1.3.1pre3 or later.) While m16-v2 contains transparent images, the images included in m16-v3 are opaque.

The easiest way to install these add-ons is just to expand the .ZIP archive into Celestia's extras directory. Zip will automatically create the subdirectory m16-v2 or m16-v3 and its contents.

These archives were updated on 6 July '03 with improved coordinates for the M16 cluster members. Their revised locations also are available in this separately downloadable file:

Errors were reduced from about 1 second of arc in Right Ascension (1/15 second of time) to better than 1/10 second of arc (1/150 second of time). The improved coordinates were obtained by using a more accurate routine to precess from B1950 to J2000, the Starlink subroutine fk425.f. See
The thumbnails below link to larger images.
[Eagle Nebula and M16]
The Eagle Nebula and M16: full view
[Eagle Nebula and M16]
The Eagle Nebula and M16: closeup
[Eagle Nebula with opaque cold gasses]
Eagle Nebula with opaque cold gasses
[The Pillars behind the gas]
The Pillars behind the gas
[a closeup, behind the covers]
A closeup, behind the covers

A closeup, behind the covers

The following images are included in both sets These images are all DDS texture files in order to provide adequate performance when loading the textures and to minimize the amount of graphics memory needed.

In m16-v2, all but the backdrop,, incorporate alpha channels which let you see though them to the images behind. In m16-v3, the alpha channels of all of the images eliminate only the black borders.

Borders were added around the smaller images instead of scaling them up to a size needed by Celestia. This should limit the damage done to the resolution to that inflicted by your graphics hardware. However, two of the images, "04086" and "phot", were scaled down from much larger versions available on the Web.

Hopefully soon Celestia will allow selecting among Nebula textures as it does among alternate planetary surface textures. In the meantime, you can edit m16-v2.dsc and comment out the Mesh declarations of those "billboards" you'd like to ignore.

This add-on has several limitations which may be corrected in a future version.

Selden Ball
July 2003


A.0 Appendices.