Looking Sharp: Images from New Gemini Spectrograph Rival View from Space
June 30, 2003
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Media Contacts:
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Peter Michaud
Gemini Observatory, Hilo, Hawai`i Phone: 808/974-2510, Cell: 808/937-0845 E-mail: pmichaud@gemini.edu |
Jennifer Akingkubedaggs
Gemini Observatory, Hilo, Hawai`i Phone: 808/974-2607 Cell: 808/960-2697 E-mail: jaking@gemini.edu |
 Gemini Observatory - GMOS-S Commissioning Team HCG 87 imaged with GMOS-S |
 Hubble Heritage Team/STScI/AURA/NASA HCG 87 imaged with the Hubble Space Telescope |
En Español - Versión adaptada en Chile
Gemini Observatory's new imaging spectrograph,
without the help of adaptive optics, recently captured images that are
among the sharpest ever obtained of astronomical objects from the
ground.
Among the images and spectra acquired during
recent commissioning of the Gemini Multi-Object Spectrograph (GMOS) on
the 8-meter Gemini South Telescope, one image is particularly
compelling. This Gemini image reveals remarkable details, previously
only seen from space, of the Hickson Compact Group 87 (HCG87). HCG87 is
a diverse group of galaxies located about 400 million light years away
in the direction of the constellation Capricornus. A striking
comparison with the Hubble Space Telescope Heritage image of this
object, including resolution data, can be viewed at http://www.gemini.edu//index.php?option=content&task=view&id=104&Itemid=0&limit=1&limitstart=2.
"Historically,
the main advantage of large ground-based telescopes, like Gemini, is
their ability to collect significantly more light for spectroscopy than
is possible with a telescope in space," said Phil Puxley, Associate
Director of the Gemini South Telescope. He explains, "The Hubble Space
Telescope is able to do things that are impossible from the ground.
However, ground-based telescopes like Gemini, when conditions are
right, approach the quality of optical images now only possible from
space. One key area - spectroscopy of faint objects, which requires
large apertures and fine image quality - is where large telescopes like
Gemini provide a powerful, complementary capability to space-based
telescopes."
GMOS-South is currently undergoing
commissioning on the 8-meter Gemini South Telescope at Cerro Pachón,
Chile. "GMOS-South worked right out of the box, or rather, right out of
the 24 crates that brought the 2-ton instrument to Chile from Canada
and the UK - just like its northern counterpart did when it arrived on
Hawaii's Mauna Kea," says Dr. Bryan Miller, head of the commissioning
team. "The GMOS program demonstrates the advantage of building two
nearly identical instruments. Experience and software from GMOS-North
have helped us commission this instrument more rapidly and smoothly
than we could have done otherwise," explains Dr. Miller. He adds,
"Although the images from GMOS-South are spectacular, the instrument is
primarily a spectrograph and that is where its capabilities are most
significant for scientists." GMOS-South is expected to begin taking
science data in August 2003.
As a multi-object
spectrograph, GMOS is capable of obtaining hundreds of spectra in one
"snapshot." The ability to deliver high-resolution images is a
secondary function. "It used to take an entire night to obtain one
spectrum," explains Dr. Inger Jørgensen, who led the commissioning of
the first GMOS instrument on the Frederick C. Gillett Gemini Telescope
(Gemini North) over a year ago. "With GMOS, we can collect 50-100
spectra simultaneously. Combined with Gemini's 8-meter mirror, we are
now able to efficiently study galaxies and galaxy clusters at vast
distances - distances so large that the light has traveled for half the
age of the Universe or more before reaching Earth. This capability
presents unprecedented possibilities for investigating how galaxies
formed and evolved in the early Universe."
GMOS
achieves this remarkable sensitivity partly because of its
technologically advanced detector, which consists of over 28 million
pixels, and partly because of multiple innovative features of the
Gemini dome and telescope that reduce local atmospheric distortions
around the telescope. "When we designed Gemini, we paid careful
attention to controlling heat sources and providing excellent
ventilation," said Larry Stepp, former Gemini Optics Manager. Stepp
elaborates, "For example, we constructed 3-story-high vents on the
sides of the Gemini enclosures. It is great to see this image that
provides such a dramatic validation of our approach."
"The
twin Gemini Telescopes offer a unique advantage," explains Director of
the Gemini Observatory Dr. Matt Mountain. "Now that both telescopes are
equipped with nearly identical GMOS instruments, we have created an
unprecedented uniform platform to coherently study and take deep
spectra of any object in the northern or southern sky at optical
wavelengths."
Upgrades to GMOS-South that will
increase its variety of capabilities are planned even as the instrument
is undergoing commissioning. An Integral Field Unit (IFU) on GMOS-South
is anticipated to begin commissioning in early 2004. Jeremy
Allington-Smith, leader of the IFU team at the University of Durham
said, "GMOS-South will soon be fitted with an integral field unit like
its sister on Gemini North. Made by the University of Durham, it uses
more than a thousand optical fibers, tipped at each end with
microscopic lenses, to dissect the object under study. This gives GMOS
a 3-D view of the target, in which each pixel in the image is replaced
by a spectrum. This innovation allows GMOS to make detailed maps of,
for example, the motion of stars and gas in galaxies."
GMOS was built as a joint partnership between Gemini, Canada and the UK. Separately, the U.S. National Optical Astronomy Observatory provided the highly capable detector subsystem and related software (http://www.noao.edu/usgp). It is anticipated that GMOS-South will be available for full scientific operations in August 2003 when astronomers from the seven-country Gemini partnership will begin using the instrument for a wide variety of scientific studies.
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Imágenes del nuevo espectrógrafo del Observatorio Gemini compiten con las tomadas desde el espacio
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Contacto para prensa:
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Maria Antonieta Garcia |
Gemini Observatory - GMOS-S Commissioning Team HCG 87 imaged with GMOS-S |
Hubble Heritage Team/STScI/AURA/NASA HCG 87 imaged with the Hubble Space Telescope |
(Junio
30, 2003-Hilo,HI) Recientemente y sin la ayuda de la óptica adaptativa,
el nuevo espectrógrafo de imagen del Observatorio Gemini fue capaz de
capturar imágenes consideradas como las más nítidas que alguna vez
hayan sido obtenidas de objetos astrónomicos desde la Tierra.
Entre
las imágenes y espectros adquiridos durante la reciente verificación
del GMOS (espectrógrafo multiobjeto de Gemini) en el telescopio de 8
metros de Gemini Sur, se obtuvo una imagen que es particularmente
sorprendente. Esta revela detalles sin precedentes , previamente sólo
posibles de ser vistos desde el espacio, del Grupo Compacto Hickson 87
(HCG87). El HCG87 es un grupo de diversas galaxias ubicadas a 400
millones de años luz en dirección hacia la constelación de Capricornio.
Una espectacular comparación con la misma imagen que fuera captada por
el Telescopio Espacial Hubble, puede ser vista en http://www.gemini.edu//index.php?option=content&task=view&id=104&Itemid=0&limit=1&limitstart=2media/images_2003.html.
"Históricamente,
una de las principales ventajas de un telescopio gigante de base en
tierra, como Gemini, es su habilidad de capturar significativamente más
luz para espectroscopía de lo que es posible con un telescopio en el
espacio", aseveró el Dr. Phil Puxley Director Asociado del telescopio
de Gemini Sur. Más adelante explica "el Telescopio Especial Hubble es
capaz de hacer cosas que son imposibles de realizarse desde tierra. Sin
embargo, los telescopios como Gemini, desde tierra, cuando tienen las
condiciones óptimas, consiguen la calidad de imágenes ópticas que hasta
ahora sólo eran posibles capturar desde el espacio. Un factor clave- la
espectroscopía de objetos opacos, los cuales requieren de grandes
aperturas y calidad de imagen fina - es cuando los telescopios como
Gemini brindan una poderosa capacidad complementaria a los telescopios
espaciales".
GMOS Sur se encuentra actualmente en
etapa de verificación en el telescopio de 8 metros de Gemini Sur
ubicado en el Cerro Pachón, IV región de Chile. "GMOS Sur empezó a
funcionar apenas salió de su embalaje, o más específicamente, apenas
salió de las 24 cajas que traían este instrumento de 2 toneladas hasta
Chile proveniente de Canadá y del Reino Unido – similar a lo que
ocurrió con su par cuando llegó a Mauna Kea en Hawaii", dijo el Dr.
Bryan Miller, líder del equipo de verificación. "El programa de GMOS
demuestra la ventaja de construir dos instrumentos practicamente
idénticos. La experiencia y el software utilizadas en el Norte nos han
ayudado a verificar el instrumento de una manera más rápida y contínua
de lo que podríamos haberlo hecho sin ello", explica el Dr. Miller
quien agrega "aunque las imágenes de GMOS Sur son espectaculares , el
instrumento es principalmente un espectrógrafo y allí es donde sus
capacidades son más significativas para los científicos". Se estima que
el GMOS Sur comience a tener información científica en agosto del 2003.
Como
espectrógrafo multiobjeto , GMOS es capaz de obtener cientos de
espectros con un sólo "presionar del obturador". La habilidad de
entregar imágenes de alta resolución es una función secundaria. "Solía
demorarse toda una noche para obtener un espectro" explica la Dra.
Inger Jørgensen, quien lideró hace poco más de un año, la verificación
del primer instrumento GMOS en el telescopio Frederick C. Gillet de
Gemini Norte."Con GMOS, podemos capturar entre 50 a 100 espectros
simultáneamente. Combinados con el espejo de 8 metros de Gemini, somos
capaces ahora de estudiar eficientemente galaxias y cúmulos de galaxias
en grandes distancias - distancias tan grandes que la luz ha viajado la
mitad de la edad del Universo o más antes de alcanzar la Tierra. Esta
capacidad presenta posibilidades imprecedentes para la investigación de
cómo se formaron y evolucionaron las galaxias en el temprano Universo".
GMOS
logra esta sensibilidad tan importante debido a su detector
tecnológicamente avanzado, el cual está conformado de 28 millones de
pixeles, y parcialmente por las características de innovación múltiple
del domo y telescopio de Gemini que reducen las distorsiones
atmosféricas locales alrededor del telescopio. "Cuando diseñamos Gemini
prestamos especial atención a controlar las fuentes de calor y a
brindar una excelente ventilación" señala Larry Stepp, antiguo Gerente
de Optica de Gemini. El agrega "Por ejemplo, nosotros construimos unas
persianas de ventilación de 3 pisos de alto en los costados de Gemini.
Es grandioso ver esta imagen que viene a validar nuestros objetivos".
"Los
telescopios gemelos de Gemini brindan una ventaja única" señala el
Director del Observatorio Gemini , Dr. Matt Mountain. "Ahora que ambos
telescopios están equipados con casi idénticos instrumentos GMOS, hemos
creado una plataforma uniforme sin precedentes para estudiar de una
forma coherente y tomar espectros profundos de cualquier objeto en el
cielo del norte o del sur en longitudes de ondas ópticas".
Mejoras
al GMOS Sur que incrementarán su variedad de capacidades están siendo
planificadas incluso mientras el instrumento se encuentra en etapa de
verificación. Se anticipa que una Unidad de Campo Integral (IFU)
estaría planificada para ser verificada en GMOS Sur a principios del
2004. Jeremy Allington - Smith líder del equipo de IFU de la
Universidad de Durham, dijo "GMOS Sur pronto se equipará con una Unidad
de Campo Integral al igual que su par en el Gemini Norte. Construido
por la Universidad de Durham, la unidad utiliza más de mil fibras
ópticas, las cuales poseen lentes microscópicos en cada una de sus
puntas, para analizar el objeto en estudio. Esto le otorga a GMOS una
vista tridimensional del objeto, en el cual cada pixel en la imagen es
reemplazada por un espectro. Esta innovación permite que GMOS haga un
mapa detallado de, por ejemplo, el movimiento de las estrellas y gas en
las galaxias".
GMOS fue construído como una asociación entre Gemini, Canada y el Reino Unido. Separadamente el Observatory Astronómico Naval de los Estados Unidos aportó con el subsistema de detector altamente sensible y su correspondiente software (http://www.noao.edu/usgp). Se estima que GMOS Sur estará de lleno en operaciones científicas en agosto del presente año cuando los astrónomos de los siete paises miembros del consorcio de Gemini comenzarán a utilizar el citado instrumento para una gran variedad de estudios científicos.
{mospagebreak}Image Resources
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Gemini Observatory - GMOS-S Commissioning Team HCG 87 imaged with GMOS-S |
Hubble Heritage Team/STScI/AURA/NASA HCG 87 imaged with the Hubble Space Telescope |
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During
commissioning in early 2003 of the Gemini Multi-Object Spectrograph
(GMOS) on the Gemini South Telescope, images and spectra were obtained
of the group of galaxies known as the Hickson Compact Group 87 (HCG
87). The Gemini image (shown, left) compares very favorably with the
Hubble Space Telescope Heritage image of this same field and
illustrates the remarkable resolution that is possible with Gemini when
atmospheric conditions are optimal. The
three Gemini images used to make the color composite image have
resolutions between 0.36 and 0.5 arcseconds (full-width-half-max) and
an unsharp mask has been applied to highlight details in the major
galaxies. Technical details on the images can be found here. |
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About Hickson Compact Group 87: One
of the primary galaxies of the HCG87 group is an edge-on galaxy with
dust lanes, which is a beautiful example of a box/peanut shaped central
bulge that the eye perceives as an X-shaped structure. This morphology
is due to the vertical instability of the orbits of millions of stars
going around the center of the galaxy. This can be caused by
interactions with other galaxies, including the accretion of dwarf
galaxy companions, or by the presence of a bar-shaped structure. Thin
bars are unstable structures that buckle about their midpoints out of
the plane of the bar. The warp in the disk of the galaxy and the lack
of a clear bar signature in the galaxy's spectrum suggest that the
X-structure in this galaxy is due to an interaction. The image also
includes other galaxies including a more face-on spiral and an
elliptical. All of these galaxies move through space together and
perform a slow graceful gravitational dance as they evolve and
influence each other's structure. References: "The Nature of Boxy/Peanut-Shaped Bulges in Spiral Galaxies". Bureau, M.; Freeman, K. C. The Astronomical Journal, 118, 126-138, July 1999. "A Merger Origin for X Structures in S0 Galaxies". Mihos, J. Christopher; Walker, Ian R.; Hernquist, Lars; Mendes de Oliveira, Claudia; Bolte, Michael. The Astrophysical Journal Letters, 447, L87, July 1995. "Orbital dynamics of three-dimensional bars - III. Boxy/peanut edge-on profiles". Patsis, P. A.; Skokos, Ch.; Athanassoula, E. The Monthly Notice of the Royal Astronomical Society, 337, 578-596, December 2002. |
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Gemini Observatory |
Sample GMOS-S Longslit Spectrum of HCG87a
A longslit spectrum of HCG87a (box/peanut galaxy). The slit was placed along the major axis (long dimension) of the galaxy and the light was dispersed with a 400 line/mm diffraction grating to detect three emission lines from gas in the galaxy. Halpha is the brightest line emitted by Hydrogen gas at 6563A. The [NII] lines are emitted by ionized nitrogen gas. Doppler shift due to movement of the gas causes the observed wavelengths of the lines to shift with position along the slit. The gas to the rights of the galaxy's center is moving away from us at 350 km/sec with respect to the center of the galaxy while gas to the left is moving towards us. This shows that the galaxy is rotating. The bright vertical spectrum along the right edge is from a nearby star. The horizontal lines along the top of the image are emission lines from gas in the earth's atmosphere.
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Gemini Observatory |
Electronics
Engineer Benjamin Irarrazaval works on the Gemini South Multi-Object
Spectrograph in the Gemini Instrument Lab on Cerro Pachon, Chile.
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Gemini Observatory |
Electronic
Systems Manager Rolando Rogers inspects the Gemini Multi-Object
Spectrograph's filter wheel at the Gemini Instrument Lab on Cerro
Pachon Chile.
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Gemini Observatory |
Instrument Technician Luis Solis works on the Gemini Multi-Object Spectrograph at Gemini South in Chile.
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Gemini Observatory |
GMOS mounted on the up-looking port of a Gemini telescope. Photo Credit: Gemini Observatory.
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