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The Horsehead Nebula

Horsehead Nebula from the
NOAO 0.9m at KPNO

Area covered in Hubble Heritage Release Image of Horsehead

Visit a Related Site of Horsehead Nebula at the NOAO Website

This image of the Horsehead nebula was taken with the NOAO Mosaic CCD camera on the National Science Foundation's 0.9-meter telescope located at Kitt Peak National Observatory near Tucson, AZ. Located in the constellation of Orion, the "hunter", the Horsehead is a dark nebula in front of the bright [pink] emission nebula IC 434. The Horsehead Nebula is roughly 1,600 light years away. The color image was generated by combining images taken through three filters (Ha, [O III], [S II]). The full image (available by clicking on the image at left) is the entire field of view of Mosaic on the 0.9-meter telescope.

Ground-based Image of Horsehead with HST image outlined. Click on the image for a larger view.

Credit: Travis Rector (NOAO)

The Internet Vote to Observe
the Horsehead Nebula

Orion Constellation
Credit: Akira Fujii

In the spring of 2000, the Hubble Heritage Project asked our visitors for suggestions on where to point the Hubble Space Telescope. For 12 weeks, Internet users young and old, including students, teachers, professional and amateur astronomers, and other scientists and nonscientists gave us many enthusiastic ideas on what to view. Our instructions were to provide the name of an astronomical object that would be visible during the late summer, and to explain why this object should be observed with the Hubble Space Telescope. By the end of the voting session, over 5,000 suggestions had been received. We read all of the proposals, which listed hundreds of different objects, ranging from our own Moon to galaxies at the farthest edges of the universe.

With so many suggestions, the Heritage Team had anticipated that the task of choosing a single winner would be difficult. In fact, however, it turned out that a single celestial object quickly emerged as the clear winner. The Horsehead Nebula in Orion received more votes than any other distinct object. As a veritable icon of astronomy, it is instantly recognizable to a large segment of the population, even those with limited contact with astronomy.

The Horsehead's large size presented a problem for our observations with Hubble; it was necessary to confine the imaging to a small portion of the object covering just the "nose" and "ears" of the horse. By early summer in 2000, we had selected the four best color filters with which to view the nebula, and had worked out exposure times and four separate pointings with the Wide Field Planetary Camera 2 (WFPC2) that would cover the desired portion of the Horsehead. These detailed specifications were then submitted to the telescope's observing queue.

In August 2000, the Sun had moved away from Orion sufficiently for the observations to begin. But then the problems started to crop up with guide stars in the field used to point the telescope and we only got an incomplete set of observations on this first attempt. The failed series of observations of the Horsehead Nebula were rescheduled with the use of different guide stars. In September 2000, observations resumed, only to have more guide star problems! So we scheduled the observations yet again, with still another change in guide stars. Finally we finished the observing in February 2001, nearly six months after the original observations were taken.

Full HST CoverageFortunately, we hope that the resulting image is one of the most spectacular Hubble images, richly rewarding all of the efforts of those who suggested the target, and those of us who worked to obtain the observations. Thanks to everyone who suggested targets for us to observe, and also to the many dedicated staff members at the Space Telescope Science Institute who had to work extra hard to obtain the images!

Comments from Horsehead Voters

Animation of Horsehead Nebula:
Including Ground- and Space-based Data!

Video Zoom
of Horsehead Nebula

609KB MPEG
Animation Credit: Bryan Preston STScI AVL

Animation Image Credits

"Backyard" view of Orion constellation, NOAO field outlined
Credit: Akira Fujii

WFPC2/Heritage field outlined NOAO 0.9m Telescope, Mosaic CCD Camera
Credit: Travis Rector, NOAO/AURA/NSF

HST WFPC2
Credit: NASA, NOAO, ESA, and The Hubble Heritage Team (STScI/AURA)