NORTH

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NORTH
SOUTH
Presentation by Erin Mentuch
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OUTLINE

• Brief Introduction
• History of the telescopes
• Telescope and Dome Design
• Scientific Instruments
• Science Capabilities
• Future

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Basic Facts

• Consists of twin 8.1 meter optical/infrared
  telescopes located on two of the best sites on
  our planet for observing the universe
• Gemini South is located at almost 2.75 km
  elevation on Cerro Pachòn, Chile
• Gemini North Telescope is located at 4.21 km
  elevation on Hawaiis Mauna Kea
• Designed for deep and detailed studies of faint
  galactic and extragalactic objects over
  relatively small fields

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HISTORY

• Gemini was built and is operated by a partnership
  of 7 countries
• United States, United Kingdom, Canada, Chile,
  Australia, Brazil and Argentina
• 1990- NSF (USA), NRC (Canada) and PPARC (UK)
  initiate twin telescope mission
• 1994- Ground breaking commences at Mauna Kea and
  Cerro Pachon
• 1995-1998- GEMINI telescopes built and installed
  on site
• 2000- GEMINI N operational
• 2001- GEMINI S operational

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COST to Build and Maintain

• Construction budget for both Gemini telescopes
  was 184 million US dollars
• Operational budget to run both Gemini telescopes
  is about 16 million /year
• This includes 4 million/year for instrument
  development
• It is estimated that each night on either of the
  Gemini telescopes is worth about 33,000

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GEMINI GOALS- Past and Present

• Complete sky coverage from excellent sites
• Excellent image quality through mirror coatings
  and adaptive optics
• Large collecting area (50m2)
• Queue scheduling to exploit best conditions
  effectively
• Use GEMINI in collaboration with 4m Telescopes
  and HST

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Telescope Design

• 8.1 m aperture
• Ritchey-Chretien Cassegrain
• Hyperbolic mirror
• Coma free
• Moving mass of 342 tons

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Active Optics

• Behind the Mirror, 120 axial actuators and 60
  lateral actuators provide small adjustments to
  the mirror
• Active optics enables Gemini's 8.1 meter primary
  mirror to be relatively thin (20 cm) while
  maintaining its precise shape

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Mirror Design

• GEMINI N
• Coating Aluminum
• Diameter 8.1 m
• Thickness 20 cm
• Mass 24 Tons
• Area 50 m2
• Reflectivity 97

• GEMINI S
• Coating Silver
• Diameter 8.1 m
• Thickness 20 cm
• Mass 24 Tons
• Area 50 m2
• Reflectivity 98.75
• (Mid Infrared)

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Reflectivity
Silver
Aluminum
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Silver Mirror Coating
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Dome Design

• Weighs 673 Tons
• 36 m in diameter, 46 m high
• Silver dome maintains better thermal stability
  than traditional white domes
• Equipped with huge (10 m wide) wind gates to
  ventilate the enclosures and flush out warm air

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Adaptive Optics

• Major goal of GEMINI is to have the best imaging
  possible
• Can be achieved by using adaptive optics
• GEMINI N is using Altair (installed early 1999)
  as well as Hokupaa
• GEMINI S is using Hokupa'a-85 and Abu

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Adaptive Optics

• Reminder We use adaptive optics to cancel out
  the effects of atmospheric turbulence
• Adaptive Optics takes a sample of starlight,
  determines how the atmosphere bent it, and then
  uses a deformable mirror to "straighten" the
  starlight out again

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Adaptive Optics-Imaging Better Than Hubble
HCG 87 with GEMINI S
HCG with HUBBLE
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SCIENTIFIC INSTRUMENTS

• Each telescope can support up to three instruments

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GEMINI N- Instrumentation

• Scientific instruments
• GMOS North - optical imager, long-slit and
  multi-object spectrograph
• NIRI - Spectrograph
• Michelle- echelle spectrograph
• NIFS- field Spectrograph

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GMOS

• GEMINI Multi-Object Spectrograph
• Built through a collaboration between the UK and
  Canada (HIA)
• Used on both GEMINI N and S
• Most popular instrument
• Spectral Coverage 0.36-1.10 ?m
• 5.5x5.5 Field of View
• Three 2048 x 2048 CCDs with 13 ?m pixels
• Spectral resolutions available range from R670
  to 4400 with a slit width of 0.5
• Up to R8,800 with smaller slit widths used with
  adaptive optics

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GMOS

• Three modes
• Multi-object spectroscopy
• Long-slit spectroscopy
• Imaging
• Multi-object Spectroscopy
• With a 5.5x5.5 field of view, can locate
  several hundred slits in a single mask
• Mask production completed with a laser milling
  machine in Hilo
• Location of slits will be determined with GMOS in
  imaging mode

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GMOS
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NIRI- Near Infrared Imager and Spectrograph

• Built by University of Hawaiis IFA
• 1024x1024 27?m ALLADIN InSb detector
• Spectral Coverage 1 to 5.5 ?m
• Three selectable cameras f/32, f/14, f/6 with
  field of views of 22x22, 51x51 and 120x120
  respectively
• Imaging with all three cameras, spectroscopy only
  with the f/6 camera
• Compatible with numerous filters ranging from
  1.25-5 ?m
• Compatible with ALTAIR (AO)

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NIRI
NIRI mounted on GEMINI N
Alladin array detector
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MICHELLE

• Mid-infrared imager and spectrometer
• Formerly in use at UKIRT
• Spectral coverage 7-26 ?m
• Contains a 320x240 SiAs IBC array detector

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MICHELLE

• Several observing modes
• Imaging through medium and narrow-band 10?m and
  20?m filters
• Long-slit spectroscopy
• R100-3000 depending on wavelength and pixel
  width
• Echelle spectroscopy
• R30000 for full spectral range

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MICHELLE

• MICHELLE mounted on GEMINI N

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NIFS

• Near Infrared Integral Field Spectrometer
• Built by Australian National Universitys
  Research School
• Critically damaged in Mt. Stromlo, Australia
  wildfire in January 2003

74 inch Telescope
NIFS
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NIFS

• Fortunately it is being rebuilt
• Expected to be delivered to GEMINI N near the end
  of 2004

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NIFS

• Has three main instrument modes
• 3D imaging spectroscopy for 0.95?m-2.4?m
• Coronagraphy for 0.1, 0.2 and 1.0 occulting
  masks
• Polarimetry for 2?m-2.4?m
• R5300
• Has a 2048x2048 HgCdTe HAWAII-2 detector
• Field of view of over 3x3
• Works with ALTAIR (adaptive optics system)

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NIFS- Light Path

• Important Component is the F-converter
• This takes a 120 diameter field and converts it
  into several 3x3 fields
• This re-images the focal plane at an enlarged
  scale onto a concave stack of 29 image slicer
  mirrors

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GEMINI S - Instrumentation

• Scientific Instruments
• GMOS - Multi-object spectroscopy
• AcqCam- optical imager
• BHROS- optical spectrograph
• GNIRS- near-IR spectrograph
• Phoenix- high resolution near-IR spectrometer

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GMOS South

• Exactly like GMOS NORTH
• Except GMOS North was optimized in the red part
  of the optical
• GMOS South is optimized for the blue and UV
  spectral range

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AcqCam

• Acquisition camera
• Has a frame-transfer CCD covering a 2 x 2
  field of view
• Used for telescope verification via short
  exposures and fast readout of bright stars
• Also used for target selection via medium-length
  exposures

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bHROS

• Bench-mounted high resolution optical (400
  nm-1000 nm) spectrograph
• R150,000
• Two modes
• Object-sky- two fibers (0.7)
• one takes sky spectrum, one takes object spectrum
• Object-only- one fibre (1)
• only takes spectrum of the target object
• Two 2048 x 2048 CCDs with 13.5 ?m pixels

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GNIRS- Near IR Spectrograph

• Built at NOAO Tucson, AZ
• Spectral Coverage 1-5.5?m
• Has multiple slits, 3 gratings, 3 prisms, 4
  cameras, 2 filter wheels and an IFU
• Several spectroscopic modes
• Long-slit with R1,700-18,000
• Cross-dispersed with R1700 and 5900
• Integral Field Unit spectroscopy
• Spectral polarimetry using GPOL

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GNIRS
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Phoenix- Near-IR Spectrometer

• Built by NOAO
• Previously used on Kitt Peaks 2m and 4m
  telescopes
• Spectral coverage 1-5?m
• R50,000 - 75,000
• Uses a 1024x1024 InSb Aladdin II array
• Its use for GEMINI S is nearing the end

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Need One More Special ToolNod and Shuffle
Technique

• Relevant features of highly red shifted galaxies
  are overwhelmed by the night sky
• The Nod and Shuffle technique allows
  astronomers to subtract away the sky spectrum
  while retaining the faint spectrum of the galaxy
• This is done through precise telescope motions
  and electronic shuffling of electrical charges
  built up on the CCD

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Nod and Shuffle- How exactly?

• Obtain a spectrum
• Move this to buffer storage on the CCD
• Move (nod) the telescope slightly
• Take another spectrum in this position
• Move first spectrum to original picture and move
  second spectrum to buffer storage
• Nod telescope back to the original position
• Repeat until enough light is collected
• Subtract the two spectra from each other to
  remove the atmospheric component

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Nod and Shuffle An Example
Storage of sky image next to object image via
charge shufflingZero extra noise introduced,
rapid switching (60s)
Typically A60s/15 cy 1800s exposure?10-3
subtraction
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GEMINI DEEP DEEP SURVEY

• Roberto Abraham of University of Toronto is
  Co-Principal Investigator
• GDDS is an ultra-deep (Klt20.6, Ilt24.5) redshift
  survey
• Unbiased- looks at galaxies with and without star
  formation (fainter)
• Targets galaxies in the redshift desert period
  between z1 and z2
• Collected over 300 galactic spectra
• Used GMOS on GEMINI N

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GDDS- Goals

• Measure space density and luminosity function of
  massive early-type galaxies
• Construct volume-averaged stellar mass function
• Measure the luminosity-weighted ages and recent
  star formation histories of 50 evolved galaxies
  at zgt1

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GDDS Discoveries

• Observed galaxies from 8-11 billion years ago
• These galaxies appear to be more mature than
  expected at this age
• Fails Hierarchal Model of Galaxies
• Need to re-think this early epoch in galactic
  evolution
• Black holes may have been more numerous in the
  early universe and accelerated galaxy formation

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GLARE- Gemini Lyman Alpha at Reionization Era

• Investigation of spectra from galaxies at very
  high redshifts
• Taken with GMOS at GEMINI S
• Discovered three galaxies at redshifts of 5.83,
  5.79 and 5.94 in the same region of the sky
  (fainter than 27 mags)

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GLARE

• Utilizes the dropout technique
• The disappearance of the image of an extremely
  distant galaxy when viewed through a UV filter
• Caused by absorption of UV rays by intergalactic
  hydrogen gas

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Stephens Quintet - WOW!
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Stephens Quintet

• Gravitational interactions have warped the shapes
  of these galaxies over millions of years
• Red dots indicate star formation regions
• Taken with GMOS on GEMINI N

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QUASARS

• A z1.93 quasar was discovered to have a
  relatively small host galaxy
• Taken with QUIRC (obsolete now) and Hokupa AO
  system on GEMINI N
• But accepted theory suggests quasars reside in
  large, massive galaxies with massive black hole
  cores
• A rule of thumb for quasars the bigger the
  galaxy, the bigger the quasar
• This discovery has forced astronomers to revamp
  their theories of quasars

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EF Eridanus

• A new type of celestial object?
• EF Eri was discovered in the 1960s as a very
  bright and variable binary system
• High EM radiation indicated that one star in the
  system was pulling mass away from its partner
• Stripping had been going on for 500 million to 5
  billion years when it stopped about 8 years ago

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EF Eridanus

• Remaining is a faint white dwarf star (0.6 M?)
  and a small dead object about 0.05M? orbiting
  each other at a distance similar to the
  Earth-Moon distance

• First object of its kind
• Classification of this object is difficult
• Too massive to be a superplanet
• Wrong composition to be a brown dwarf
• Too low in mass to be a star

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Future Goals

• New observatory, still long life ahead
• Key Questions Posed at the Aspen Conference in
  June 2003
• How do galaxies form?
• What is the nature of dark matter on galactic
  scales?
• What is the relationship between super-massive
  black holes and galaxies?
• What is dark energy?
• How did the cosmic "dark age" end?
• How common are extra-solar planets, including
  Earth-like planets?
• How do star and planetary systems form?
• How do stars process elements into the chemical
  building blocks of life?

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THANKS FOR LISTENING

• Get more information on GEMINI at
• http//www.gemini.edu/

• ANY QUESTIONS?