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KECK OBSERVATORY
MAUNA KEA SUMMIT
ISLAND OF HAWAI‘I

2007 April 3

INNOVATIVE TECHNOLOGIES:
ADAPTIVE OPTICS / LASER GUIDE STAR ~ AO/LGS

Many celestial objects are very faint, such as those that lie in the most remote regions of the universe. Earth’s turbulent atmosphere blurs celestial images that arrive at the telescope, making observation and analysis difficult. But an extraordinary new technology is revolutionizing ground-based astronomy. This 12-watt laser beam creates a bright “artificial star“ high in the atmosphere, along the line of sight to the object being observed. Astronomers then measure the atmospheric disturbance, or twinkling in the artificial star, and make rapid counter-corrections by continually deforming a small flexible mirror in the light path. Both laser “star” and faint target object then come into precise focus, yielding substantially better data than would otherwise be possible.

The laser guide-star beam has very little flare over the length of its 90-kilometer column. However, it appears here as an elongated fan shape due to the 180-second time exposure.The "fan" reveals and records the path of the laser sweeping across the sky as the moving telescope tracks the celestial object being observed. The blurred dome is evidence of continual rotation to maintain alignment of the open shutter with the telescope.

The landscape is brightened by a newly-risen moon, disc illumination 98%.

OBSERVING PROGRAM:

Using the Keck II 10-meter telescope shown in this photograph, Caltech astronomer Nick Scoville is observing remotely from a control room at Keck Headquarters in Kamuela. He and his colleagues Peter Capak (Caltech), James Larkin (UCLA), and Shelley Wright (UCLA) are looking at some of the most energetic objects in the universe—quasi-stellar objects, otherwise known as quasars. A quasar is an extremely luminous active galactic nucleus harboring a supermassive black hole which is devouring prodigious amounts of matter. The team is hoping to detect as-yet-unseen host galaxies that spawned the highly visible quasars in the early universe. It is anticipated that Larkin’s innovative OSIRIS spectrograph will separate the relatively bright quasar point source light from the much more subtle light emitted by its host galaxy. 

OSIRIS was designed by Larkin to work specifically with the Keck AO system and to dissect tiny portions of the sky. It can analyze light from over 3000 adjacent regions simultaneously, allowing astronomers to measure the chemical makeup of objects, as well as rotations and more complex motions over an extended area.

Nick Scoville and Shelley Wright explain the program in more detail:

"Our project was aimed at detecting host galaxies of the highest redshift quasars within the SLOAN survey. These are at redshift 6, corresponding to only one billion years after the Big Bang. Although the quasars are easily detected, host galaxies have never been seen. Yet given what we know about quasars in the local universe, the hosts should be detectable as long as one can separate bright quasar light from the host galaxy. This experiment provides a unique opportunity to observe the most massive galaxies when they were young in the early universe. The combination of high spatial resolution from the Keck Adaptive Optics / Laser Guide Star system and OSIRIS' ability to disentangle light from the quasar and host galaxy makes this project viable."

A VIEW FROM MAUNA KEA ~ SACRED MOUNTAIN OF HAWAI‘I

Mauna Kea holds profound religious and cultural significance for Native Hawaiians. It embodies their divine ancestral origins and connection to Creation. At 13,796 feet / 4,205 meters in elevation on the Island of Hawai‘i, it last erupted about 4400 years ago. The now-dormant volcano is only 120 feet higher than its active neighbor Mauna Loa 27 miles to the south. Seen from below and framed by palm trees and azure waters, the snow-cloaked summit of Mauna Kea inspires awe and veneration—its Hawaiian name means “White Mountain”. The star-filled sky above offers unsurpassed clarity for some of the world’s most advanced telescopes as they unravel mysteries of the universe. Upon its flanks are hallowed Hawaiian sites, ancient paths, rare plants and animals, and a unique and fragile ecosystem. Please walk gently and respectfully on Mauna O Wākea, the Sacred Mountain of Hawai‘i.

EXPOSURE DATA

Nikon D2x
Nikkor 12-24 DX f/4 zoom lens
ISO digital: 125  /  f/4.5
Exposure: 180 seconds

Read more about LASER GUIDE STAR: Terrestrial Photography. This is primarily a discussion about the creation of two of my 2007 Keck Observatory laser images that illustrate author Robert Irion's feature article "Homing in on Black Holes" in the 2008 April Smithsonian Magazine. Although the image on this page did not appear in the magazine, logistics of photographing the laser still apply.

COPYRIGHT

All images and text are property of Laurie Hatch Photography; unauthorized use is a violation of copyright law. You are welcome to email me with your useage requests.

FOR MORE INFORMATION

W. M. Keck Observatory

Keck Adaptive Optics / Laser Guide Star

UCLA ~ OSIRIS Spectrograph 

‘Imiloa: Astronomy Center of Hawai‘i

Mauna Kea Visitor Information Station

The photographer thanks the astronomers and Keck staff for their invaluable assistance and collaboration in producing this photograph. 

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