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Delta 4-Heavy launch
The Boeing Delta 4-Heavy rocket is launched from Cape Canaveral on its demonstration flight. (4min 35sec file)
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Onboard the Heavy
An onboard camera records the launch of Boeing's Delta 4-Heavy rocket from liftoff through separation of the outer boosters. (4min 40sec file)
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Launch of Atlas 5
The Lockheed Martin Atlas 5 rocket launches at 7:07 a.m. EST from Cape Canaveral carrying the AMERICOM 16 communications spacecraft. (6min 22sec file)
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Press site view
The sunrise launch of Atlas 5 is shown in this view from the Kennedy Space Center press site at Complex 39. (QuickTime file)
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Rocket rollout
Riding on its mobile launching platform, the Atlas 5 rocket is rolled from its assembly building to the launch pad at Complex 41 just hours before the scheduled liftoff time carrying AMC 16. (4min 41sec file)
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Atlas 5 news briefing
Mission officials hold the pre-launch news conference in Cape Canaveral on Thursday, Dec. 16 to preview the flight of Atlas 5 with AMC 16. (40min 41sec file)
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AMC 16 launch preview
Preview the launch of Lockheed Martin's Atlas 5 rocket carrying the AMERICOM 16 communications spacecraft with this narrated animation package. (2min 52sec file)
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The AMC 16 spacecraft
This narrated movie provides an overview of the Lockheed Martin-built AMC 16 spacecraft for operator SES AMERICOM. (3min 30sec file)
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Deep Impact overview
Rick Grammier, NASA's Deep Impact project manager from the Jet Propulsion Laboratory, provides a detailed overview of the spacecraft and its mission. (4min 54sec file)
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Science preview
Deep Impact principal investigator Michael A'Hearn explains how the comet collision will occur and what scientists hope to learn. (7min 11sec file)
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Pre-flight news briefing
The pre-flight news conference is held at NASA Headquarters on December 14 to preview the Deep Impact mission to intercept a comet and blast a projectile into it. (54min 19sec file)
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Galactic fireworks image to kick off the New Year
Posted: January 1, 2005

Like the annual New Year's fireworks display, astronomers at Gemini Observatory are ushering in 2005 with a striking image that dazzles the eye with stellar pyrotechnics.

Gemini North GMOS iimage of the "Fireworks Galaxy" NGC 6946 in the Constellation of Cepheus. Credit: Gemini Observatory /Travis Rector, University of Alaska Anchorage
In the image, the face-on spiral galaxy NGC 6946 is ablaze with colorful galactic fireworks fueled by the births and deaths of multitudes of brilliant, massive stars. Astronomers suspect that massive stellar giants have been ending their lives in supernova explosions throughout NGC 6946 in rapid-fire fashion for tens of millions of years.

"In order to sustain this rate of supernova activity, massive, quickly evolving stars must form or be born at an equally rapid rate in NGC 6946," said Gemini North Associate Director, Jean-Rene Roy. "Its stars are exploding like a string of firecrackers!"

Astronomers speculate that if just a million years of this Galaxy's history were compressed into a time-lapse movie lasting a few seconds, there would be nearly constant outbursts of light as new stars flare into view, while old ones expire in spectacular explosions. Over the past century, eight supernovae have exploded in the arms of this stellar metropolis, occurring in 1917, 1939, 1948, 1968, 1969, 1980, 2002, and 2004. This makes NGC 6946 the most prolific known galaxy for supernovae during the past 100 years.

By comparison, the average rate for such catastrophic stellar outbursts in the Milky Way is about one per century, and only four have been recorded over the last thousand years. The last known supernova went off in our galaxy in the constellation Ophiuchus in 1604.

Yet, it is the ubiquitous occurrence of starbirth throughout NGC 6946 and not its supernovae that lend this galaxy its blazingly colorful appearance. For reasons not completely understood, it experiences a much higher rate of star formation than all the large galaxies in our local neighborhood. The prodigious output of stellar nurseries in this galactic neighbor eventually leads to accelerated numbers of supernova explosions.

Starbirth regions exist in most galaxies, particularly in spirals, and are obvious as clouds of predominantly hydrogen gas called H II regions. These areas coalesce over millions of years to form stars. Young, hot, massive stars formed in these regions emit copious amounts of ultraviolet radiation, which strip the electrons from hydrogen atoms in which they are embedded. When these ionized hydrogen atoms re-associate with electrons they radiate in a deep red color (at a wavelength of 656.3 nanometers) as the electrons transition back to lower energy levels.

This Gemini image of NGC 6946 utilizes a selective filter specifically designed to detect the radiation emanating from the starbirth regions. Additional filters help to distinguish other details in the galaxy, including clusters of massive blue stars, dust lanes, and a yellowish core where older more evolved stars dominate.

NGC 6946 lies between 10 and 20 million light-years away on the border between the constellations of Cepheus and Cygnus, and was discovered by Sir William Herschel (1738- 1822) on September 9, 1798. It continues to fascinate astronomers, who estimate that it contains about half as many stars as the Milky Way. They often use it to study and characterize the evolution of massive stars and the properties of interstellar gas. As viewed in the new Gemini optical image, we see only the "tip of the iceberg" of this galaxy. Its optical angular diameter is about 13 arcminutes, but viewed at radio wavelength at the frequency of neutral hydrogen (1420 Mhz or 21-cm line), it extends considerably more than the angular diameter of the Moon.

Gemini Observatory is an international partnership managed by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation.

The national research agencies that form the Gemini Observatory partnership include: the US National Science Foundation (NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the Canadian National Research Council (NRC), the Chilean Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT), the Australian Research Council (ARC), the Argentinean Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) and the Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq).



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