Keck treasury surveys add deep spectral data to "GOODS-North" field(Forwarded)

W.M. Keck Observatory
Kamuela, HI

Media Contact:
Laura K. Kraft, (808) 885-7887,

December 31, 2003

KECK TREASURY SURVEYS ADD DEEP SPECTRAL DATA TO "GOODS-North" FIELD

KAMUELA, Hawaii -- Two teams of astronomers based at the W. M. Keck Observatory
and the University of Hawaii have completed deep new spectroscopic surveys of
galaxies within the boundaries of the northern hemisphere field of the Great
Observatories Origins Deep Survey (GOODS). The "Team Keck Treasury Redshift
Survey" (TKS) is available to the public on the Web at:
http://www2.keck.hawaii.edu/science/tksurvey/
while a parallel project led by University of Hawaii astronomers is available at
http://www.ifa.hawaii.edu/~cowie/hhdf/acs.html
These surveys will improve the value of existing GOODS images and will help
researchers distinguish whether a faint blob seen in the GOODS images
corresponds to a nearby star or a distant quasar, information that cannot be
gleaned from space telescope pictures alone.

"Our Team Keck survey follows in the footsteps of several key redshift surveys
of the Hubble Deep Field-North completed with the Keck Low Resolution Imaging
Spectrograph between 1996 and 2000, and is complemented by two similar projects,
Len Cowie's DEIMOS survey and a sample of fainter targets observed with the
Gemini North telescope," said Frederic Chaffee, Director of the W. M. Keck
Observatory in Hawaii and participant in the TKS project. "We saw the need for
this data set and because we have one of the few telescopes in the world that
can do this, decided to donate the necessary observing time to the project."

The GOODS effort is the most ambitious survey of the early universe ever
conducted by the world's largest and most sensitive space- and ground-based
telescopes. It includes data from the Spitzer Space Telescope, Hubble, Chandra,
XMM-Newton and from the most powerful ground-based facilities in the world, such
as the W. M. Keck Observatory. The GOODS project provides extremely deep,
multi-wavelength observations for an exceptionally wide range of targets at
varying distances in two regions of the sky, one in the northern hemisphere and
one in the south. The GOODS-North survey spans a region 16 by 10 arcminutes in
size, or about one-fourth the size of the full moon. The galaxy redshift surveys
led by Team Keck the University of Hawaii team will be used in conjunction with
other surveys for a great variety of applications for this intermediate- and
high-redshift data set.

University of Hawaii astronomer Len Cowie leads the Hawaii survey of the
GOODS-North region and, with Amy Barger at the University of Wisconsin, has led
efforts to identify these sources in deep X-ray and submillimeter observations
of the same field. Prof. Cowie commented, "The GOODS fields take advantage of
the new large cameras that survey larger areas of sky compared to the original
Hubble Space Telescope studies. The wider fields allow us to study rare and
exotic objects, such as X-ray bright galaxies with black holes at their nuclei
or very heavily dust-enshrouded star-forming galaxies in the early universe. The
spectra can also be combined with our distant galaxy searches to see the way
that structure develops over the universe's first billion years."

The TKS and University of Hawaii catalogs provide redshifts for 1946 objects in
the GOODS-North field to magnitudes as faint as 24.4 (at 7,000 Angstroms). The
survey's faintest targets are over twenty million times fainter than the dimmest
objects visible to the unaided human eye. The objects with measured redshifts
include 163 stars within our own Milky Way galaxy, plus galaxies and quasars as
distant as redshift 5.19. The redshift and quality of each object's spectrum was
independently classified by at least two team members to ensure consistency in
the final catalog.

In addition to the measured redshifts, the Keck and University of Hawaii teams
will ultimately make all the spectra publicly available for downloading on their
Web sites. Being able to analyze these spectra independently will help
astronomers worldwide extract additional information that cannot be obtained
from the redshifts alone, such as velocity dispersions, elemental abundances and
dynamical measurements that enable meaningful comparisons between astronomical
objects.

These surveys were made possible through the use of one of the world's largest
and most powerful astronomical survey instruments, the Deep Imaging Multi-Object
Spectrograph (DEIMOS) installed on the Keck II 10-meter telescope. DEIMOS powers
through surveys by taking high-resolution spectra of more than 130 objects at
once, allowing the entire survey of over 2000 objects to be completed in the
equivalent of five nights on the telescope.

The surveys were conducted over a period of twelve nights in the spring of 2003
with additional observations provided by the Deep Extragalactic Evolutionary
Probe (DEEP2) Survey team. Astrometry for the catalog was obtained by
cross-correlating the United States Naval Observatory and Sloan Digital Sky
Survey catalogs as well as radio observations from the VLA. For additional
technical information, such as mask design, observing modes and data reduction
techniques, please visit the TKS Web site at
http://www2.keck.hawaii.edu/science/tksurvey/

The TKS team includes Gregory Wirth, principal investigator, and Paola Amico,
Fred Chaffee, Al Conrad, Bob Goodrich, Grant Hill, James Lyke, Shui Kwok, Jeff
Mader, David Le Mignant, and Hien Tran of the California Association for
Research in Astronomy at the W. M. Keck Observatory in Hawaii. TKS
collaborators include Christopher Willmer,

Sandra Faber, and David Koo of the University of California Observatories/Lick
Observatory and UC Santa Cruz, plus Marc Davis of UC Berkeley. University of
Hawaii researchers Len Cowie, Amy Barger, Peter Capak, Esther Hu and Toni
Songaila completed the University of Hawaii survey and also served as
co-investigators in the TKS program. The Keck team will also participate in
CATS, the Center for Adaptive Optics Treasury Survey, which will use adaptive
optics to produce detailed, near-infrared images of these same galaxies in the
GOODS-North field.

The TKS project was funded in part by the National Science Foundation's "Small
Grants for Exploratory Research" initiative, under Grant No. AS-0331730 and the
University of Hawaii effort by NASA and NSF grants primarily. Any opinions,
findings and conclusions or recommendations expressed herein do not necessarily
reflect those of the National Science Foundation or NASA.

The W. M. Keck Observatory is managed by the California Association for Research
in Astronomy, a scientific partnership among the California Institute of
Technology, the University of California, and the National Aeronautics and Space
Administration. Together, these groups manage the world's largest optical and
infrared telescopes. Visit the observatory online at
http://www.keckobservatory.org/

IMAGE CAPTIONS:

[Image 1:
http://www2.keck.hawaii.edu/news/tksurvey/ktrs12big.jpg (80KB)]
A sample image showing a small part of the GOODS-North field as seen in red
light. The green markings represent DEIMOS slits that were machined according to
the position of galaxies in the GOODS-North field. The DEIMOS instrument enables
astronomers to acquire high-resolution spectra of more than 130 objects in a
single exposure.

Image Credit: W. M. Keck Observatory

[Image 2:
http://www2.keck.hawaii.edu/news/tks...echart_dec.jpg (122KB)]
A "pie diagram" map showing how the galaxies in the survey are distributed in
space. Note the numerous "walls" and "voids" observed in this field due to
clustering of galaxies.

Image Credit: W. M. Keck Observatory

[Image 3:
http://www2.keck.hawaii.edu/news/tks...fig-z-vs-R.jpg (120KB)]
This diagram plots the distance of galaxies (as measured by their redshift, z)
versus their brightness (magnitude, in which higher numbers indicate fainter
objects). The faintest objects that can be seen with the unaided human eye are
over 15 million times brighter than the faintest objects captured in this Keck
survey.

Image Credit: W. M. Keck Observatory

[Image 4:
http://www2.keck.hawaii.edu/news/tksurvey/fig-zdist.jpg (77KB)]
This plot shows the number of galaxies as a function of redshift in the Keck
survey. Redshifts, which are proportional to a galaxy's distance from Earth,
were measured from emission lines (Hydrogen Balmer series, [N II], [S II], [O
III], [O II]) and Calcium (H and K) absorption features in galaxy spectra.

Image Credit: W. M. Keck Observatory