The Eagle Nebula and M16

m16-v2 and m16-v3

LoDN: m16-v2.zip (10MB 2-Jul-03; updated 6-Jul-03) (transparent pictures)

Note
Because of its popularity, this file now is available only from the high performance LoDN file service. LoDN uses Java WebStart. If you don't have it yet, you may need to install Sun's Java2 JRE (Java Runtime Environment).
m16-v3.zip (8.5MB 3-Jul-03; updated 6-Jul-03) (opaque pictures)

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.

Archive:  m16-v2.zip   
(the "-v3" archive contains the same filenames but replaces "-v2" with "-v3")

  Length     Date   Time    Name
 --------    ----   ----    ----
     9227  07-01-03 22:21   m16-v2/m16-alignment.html
    11189  07-01-03 07:52   m16-v2/m16-cluster.stc
     7698  07-03-03 12:33   m16-v2/m16-v2-readme.html
     3431  07-01-03 22:15   m16-v2/m16-v2.dsc
     8283  07-02-03 21:18   m16-v2/m16-v2a.jpeg
     7903  07-02-03 21:18   m16-v2/m16-v2b.jpeg
     7633  07-03-03 00:41   m16-v2/m16-v3a.jpeg
    10324  07-03-03 00:53   m16-v2/m16-v3b.jpeg
        0  07-02-03 20:09   m16-v2/models/
        0  07-02-03 20:09   m16-v2/textures/
      704  06-30-03 22:36   m16-v2/models/04086.3ds
      708  06-28-03 09:45   m16-v2/models/1995-44-a.3ds
      704  06-28-03 11:56   m16-v2/models/eagle.3ds
      707  06-27-03 06:38   m16-v2/models/m16atlas.3ds
      708  06-28-03 10:41   m16-v2/models/m16c1_eso.3ds
      710  06-25-03 07:45   m16-v2/models/phot-37a-01.3ds
        0  07-02-03 20:09   m16-v2/textures/medres/
  5592560  06-30-03 22:34   m16-v2/textures/medres/04086.dds
  5592560  07-01-03 20:57   m16-v2/textures/medres/1995-44-a.dds
  1398256  06-29-03 17:43   m16-v2/textures/medres/eagle.dds
  1398256  06-27-03 07:06   m16-v2/textures/medres/m16atlas.dds
  1398256  06-28-03 11:45   m16-v2/textures/medres/m16c1_eso.dds
  5592560  06-28-03 10:50   m16-v2/textures/medres/phot-37a-01.dds
 --------                   -------
 21042377                   23 files

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:

m16-cluster.stc (12KB, 6Jul03)

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 http://star-www.rl.ac.uk/.

The thumbnails below link to larger images.

The Eagle Nebula and M16: full view	The Eagle Nebula and M16: closeup
Eagle Nebula with opaque cold gasses	The Pillars behind the gas	A closeup, behind the covers Cel://URL: A closeup, behind the covers

The following images are included in both sets

04086.dds	(2Kx2K)	A false-color image of the Eagle Nebula, from NOAO
m16atlas.dds	(1Kx1K)	An infra-red mosaic of stars in the Nebula, from 2MASS
1995-44-a.dds	(2Kx2K)	The famous picture of the "Pillars of Creation," from NASA
phot-37a-01.dds	(2Kx2K)	A high resolution infra-red mosaic of stars, from ESO
m16c1_eso.dds	(1Kx1K)	A closeup IR image of the top of Pillar #1, from ESO
eagle.dds	(1Kx1K)	A picture showing the cold nebulosities (-100 degrees Centigrade) that fill the Nebular region, from ESA's ISO.

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, 04086.dds, 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.

Most prominent is that the stars in the cluster are all shown at the same nominal distance of 7000 light years. Determining their relative distances from their apparent magnitudes, UBV colors and luminosity types will take more effort than I can invest right now.
To me, many of the star images look like dirt smudges on glass. The stars in the infra-red mosaics from 2MASS and ESO are saturated, so that they have the same brightness over a relatively large area. (Presumably this is a side-effect of converting from 16bit FITS images to 8bits/channel color images.) As a result, the transparency masks, which are just grey-scale versions of the original images, can't give them translucent edges.

Selden Ball
July 2003

Acknowledgements:

Grant Hutchison provided a spreadsheet calculator which greatly improved the alignment of the images.
The information about the individual stars in the M16 cluster was obtained from http://obswww.unige.ch/webda/
The original images were created by the research groups credited below.
NOAO false color image of the Eagle Nebula used with implicit permission: educational outreach by an amateur astronmer.
Minimum credit line: T.A.Rector (NRAO/AUI/NSF and NOAO/AURA/NSF) and B.A.Wolpa (NOAO/AURA/NSF) http://www.noao.edu/image_gallery/html/im0725.html
2MASS mosaic atlas of the M16 region used with implicit permission with inclusion of this acknowledgement: "This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation." http://www.ipac.caltech.edu/2mass/gallery/powcap36.html
closeup image of the "Pillars of Creation" used with explicit permission from Jeff Hester. Credit: Jeff Hester and Paul Scowen (Arizona State University), and NASA http://hubble.stsci.edu/newscenter/archive/1995/44/image/a
quoted from the URL referenced below: ESO PR Photos 37a-e/01 and Video Clips 08a-b/01 may be reproduced, if credit is given Mark McCaughrean and Morten Andersen of the Astrophysical Institute Potsdam (AIP), and the European Southern Observatory (ESO). "http://www.eso.org/outreach/press-rel/pr-2001/phot-37-01.html
IR image of cold nebulosities used with implicit permission: as requested on the ESA/ISO credit page at http://www.iso.vilspa.esa.es/science/credit.html
Credit: ESA/ISO, CAM & The ISOGAL Team Taken from the ISO Science Results Gallery. See also: http://www.iso.vilspa.esa.es/science/ and http://www.iso.vilspa.esa.es/galleries/ism/eagle.htm
See also:
- Selden's List of Resources for Celestia

A.0 Appendices.

A.1: Signature.

A.2: Admonishment.

seb@lepp.cornell.edu

Private Message

If you don't tell me that something's missing, unclear or wrong, I can't improve it.

A.3: Disclaimer.