ca. Mar 2, 2004

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TheLargeMillimeterTelescope
ca. Mar 2, 2004
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Gopal Narayanan, Min Yun, F. Peter
Schloerb University of Massachusetts Luis
Carrasco Instituto Nacional de Astrofisica,
Optica, y Electronica presented on behalf of the
INAOE-UMass LMT Collaboration
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Sierra NegraThe LMT Site
Pico de Orizaba
Sierra Negra

• state of Puebla, MX
• excellent mm-wave transmission
• 4600m elevation
• 19 degrees Latitude
• Benign conditions
• Development nearly complete

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LMT Specifications
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LMT Time Line

• 1997 Site Selection
• 1997-2000 Antenna Design
• 1999-2002 Site Preparation and installation of
  Foundation
• 2001 Factory Steel Fabrication and Trial
  Assembly
• 2002-2004 Installation of Steel at Site
• 2004-2006 Fabrication of Surface Panels
• 2005-2006 Installation of Surface Panels
• 2005 Commissioning Begins

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Backstructure
Surface Segments
Elevation Wheels
LMT Design
Receiver Cabin
Alidade
Foundation
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Construction at Site
January 2001
January 2002
February 2002
April 2003
May 2002
July 2002
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Present Status at SiteApril 2004
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Initial LMT Instruments

• Spectral Line
• SEQUOIA 32 element array for 3mm band
• Array Autocorrelation Spectrometers
• Redshift Receiver 3mm ultrawide band receiver
• 1mm SIS Receiver
• Continuum
• BOLOCAM II 144 element focal plane array
• SPEED special array for spectral energy
  distribution measurements

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Goldsmith, Narayanan, Heyer, Snell Brunt (2004)
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Redshift Search Receiver

• Ultra-wideband receiver for astronomical search
  for the highly redshifted spectral lines from
  distant galaxies.
• 75-111 GHz gives high probability of detecting
  one line from galaxies with redshift greater than
  1.1 and 2 lines for Z gt 3

2mm, 5mm PWV, TRCR 60K
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• Dual polarization two beams
• Backend spectrometer is analog autocorrelator
  with 6.5 GHz bandwidth per section. 30 MHz
  resolution.

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LMT Redshift Measurements
Simulations based on dusty QSO BR 1335-0417.
ULIRG Line Ratios
LMT has sensitivity to conduct follow-up studies
on objects discovered in continuum surveys.
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1mm SIS Commissioning Receiver for LMT (testbed
for future focal-plane array)
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First Generation Continuum Receivers for LMT

• BOLOCAM II
• Imaging continuum receiver
• copy of the BOLOCAM instrument
• (Caltech, JPL, Cardiff, Colorado)
• 144 element focal plane array
• key technology for
• Herschel/SPIRE
• BLAST

BOLOCAM detector array
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LMT Continuum Studies of Distant Objects
Simulation of 1 hour LMT observation with
Bolocam II at 1.1 mm 9.5x9.5 arcmin (0.02 sq.
deg.) 0.5 mJy rms
LMT will discover many 1000's of protogalaxies
with continuum maps.
Simulation by Chapin, Hughes and Gaztenaga -
INAOE
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First Generation Continuum Receivers for LMT

• SPEED
• designed to measure mm-wave SED of previously
  detected objects
• simultaneous multi-frequency measurements
• matched beams in all bands
• high per-pixel sensitivity
• takes advantage of new bolometer technologies
• TES detectors
• Frequency Selective Bolometers

Ch.4
Ch.3
Ch.2
Ch.1
FSB Detector
FSB Backshort
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Protogalaxy Interrogation with SPEED
SED of CFRS14A
SPEED 5s sensitivities after 4 minutes of
integration at LMT.
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Comparison of LMT to Other Telescopes
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Performance Comparison With Respect to the LMT
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• Analog Autocorrelator
• Like digital autocorrelator but delays and
  multiplies done with analog circuitry. No input
  digitizer, so no loss of S/N. Much wider
  bandwidth practical.
• Analog delay lines Nyquist sampled for 8 GHz
  bandwidth. Only 1.5-8 GHz used.
• 64 lags on each tapped line, 4 lines per board.
  256 lags total giving 31 MHz resolution, all on a
  single circuit board.
• Taps are summed and multiplied with silicon
  diodes.
• Circuit board includes A/D converters and digital
  signal processing.
• 24 boards cover full receiver bandwidth of 144
  GHz.
• Total materials cost about 10/resolution element.

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LMT Sensitivity to Distant Dusty Starburst
Galaxies
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OperationsThe Large Millimeter Telescope
Observatory

• LMTO Role
• Telescope maintenance and operation
• Development of plans for upgrades
• Telescope user support
• Outreach
• LMTO Organization
• Governing Board composed of INAOE and UMass
  personnel oversees LMTO.
• LMTO is separate entity with an indepentent
  Director and Staff.

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LMTO A Scientific Collaboration between the US
and Mexico
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LMT Site MM-wave Transmission
2mm ppt-H2O
8mm H2O
8mm ppt-H2O
2mm H2O
Site Opacity Quartiles based on
Radiometric Measurements
Predicted Transmission for 2mm and 8mm ppt water
vapor
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Antenna Design

• Antenna Designer MAN Technologie
• "Open Air" Design (no enclosure).
• Active Surface
• 180 trapezoidal surface segments.
• Actuators at four corners of segments.
• open-loop lookup table for positioning.
• Use of Active Surface eliminates gravitational
  distortion as major error source.

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Antenna Fabrication

• Steel Fabrication
• Adriann's de Mexico, Tlanepantla, Mexico
• Supervision by Antedo, Inc., Cupertino CA.
• Steel Fabrication is complete antenna being
  assembled at site
• Surface Panels
• Design and Development by Composite Optics Inc.
  (COI), San Diego, CA
• Fabrication at Adriann's de Mexico
• Panel fabrication to begin this year.

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LMT Surface Segment
Surface Panel
Actuator for Computer Control
Subframe
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Critical Design Review for First Panel
Composite Optics Inc. San Diego CA
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