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Hubble Space Telescope Cutaway

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Hubble Space Telescope Field of View

• WFC3• ACS• STIS• COS• FGS

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HST: WFC3

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HST: WFC3

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HST: ACS

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HST: ACS

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HST: STIS

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HST: STIS

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Spitzer Space Telescope

• IRAC• IRS• MIPS

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Spitzer Space Telescope: IRAC

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Spitzer Space Telescope: IRS

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Spitzer Space Telescope: MIPS

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Chandra Space Telescope

• ACIS• HRC• Spectral modes

Advanced Charged Couple Imaging Spectrometer (ACIS): Ten CCD chips in 2 arrays provide imaging and spectroscopy; imaging resolution is 0.5 arcsec over the energy range 0.2 - 10 keV; sensitivity: 4x10-15 ergs/cm2/sec in 105 s

High Resolution Camera (HRC): Uses large field-of-view mircro-channel plates to make X-ray images: ang. resolution < 0.5 arcsec over field-of-view 31x31 arc0min; time resolution: 16 micro-sec sensitivity: 4x10-15 ergs/cm2/sec in 105 s

High Energy Transmission Grating (HETG): To be inserted into focused X-ray beam; provides spectral resolution of 60-1000 over energy range 0.4 - 10 keV

Low Energy Transmission Grating (LETG): To be inserted into focused X-ray beam; provides spectral resolution of 40-2000 over the energy range 0.09 - 3 keV

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Chandra Space Telescope: ACIS

• Chandra Advanced CCD Imaging Spectrometer (ACIS)

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Chandra Space Telescope: HRC

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Chandra Space Telescope: Spectroscopy

• High Resolution Spectrometers - HETGS and LETGS • These are transmision gratings

– low energy: 0.08 to 2 keV – high energy: 0.4 to 10 keV (high and medium resolution)

• Groove spacings are a few hundred nm.

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Gemini (North)

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Gemini (South)

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JWST

• NIRCAM

• NIRSPEC

• MIRI

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JWST: NIRCAM

• Nyquist-sampled imaging at 2 and 4 microns -- short wavelength sampling is 0.0317"/pixel and long wavelength sampling is 0.0648"/pixel

• 2.2'x4.4' FOV for one wavelength provided by two identical imaging modules, two wavelength regions are observable simultaneously via dichroic beam splitters.

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JWST: NIRSPEC

• 1-5 um; R=100, 1000, 3000

• 3.4x3.4 arcminute field

• Uses a MEMS shutter for the slit

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JWST: MIRI

• 5-27 micron, imager and medium resolution spectrograph (MRS)

• MIRI imager: broad and narrow-band imaging, phase-mask coronagraphy, Lyot coronagraphy, and prism low-resolution (R ~ 100) slit spectroscopy from 5 to 10 micron.

• MIRI will use a single 1024 x 1024 pixels Si:As sensor chip assembly. The imager will be diffraction limited at 7 microns with a pixel scale of ~0.11 arcsec and a field of view of 79 x 113 arcsec.

• MRS: simultaneous spectral and spatial data using four integral field units, implemented as four simultaneous fields of view, ranging from 3.7 x 3.7 arcsec to 7.7 x 7.7 arcsec with increasing wavelength, with pixel sizes ranging from 0.2 to 0.65 arcsec. The spectroscopy has a resolution of R~3000 over the 5-27 micron wavelength range. The spectrograph uses two 1024 x 1024 pixels Si:As sensor chip assemblies.

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JWST: MIRI MRS

NIRSPEC/Keck Optical LayoutSide View

NIRSPEC/Keck Optical LayoutTop View

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Large CCD Mosaics

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LSST Has a Big Camera

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LSST Has a Big Focal Plane

Guide Sensors (8 locations)

Wavefront Sensors (4 locations)

3.5 degree Field of View (634 mm diameter)

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History of Infrared Light Detection

• Herschel’s detection of IR from Sun in 1800

• Johnson’s IR photometry of stars (PbS) mid 60’s

• Neugebauer & Leighton: 2um Sky Survey (PbS), late 60’s

• Development of bolometer (Low) late 60’s

• Development of InSb (mainly military) early 70’s

• IRAS 1983

• Arrays (InSb, HgCdTe, Si:As IBCs) mid-80’s

• NICMOS, 2MASS, IRTF, UKIRT, KAO, common-user instruments, Gemini, etc.

• JWST and the search for cosmic origins

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Detector Size

Applications

Imaging (single photon counting)

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Figures Courtesy of Don Hall (University of Hawaii)

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Fermi Gamma-ray Large Area Space Telescope (GLAST)

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GLAST LAT

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Gamma Ray Detection Airshowers

• It is possible to detect gamma rays by the presence of their by-products produced in Earth’s atmosphere.

• Ground-based gamma ray telescopes actually detect Cherenkov radiation emitted by high energy particles produced through the interaction of the gamma rays and atmospheric particles.

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Caltech Submillimeter Observatory (CSO)

• CSO has a 10.4m primary dish.

• SHARCII has 350, 450, 850um passbands, 12x32, 2.6x1amin field.

• Dry nights lead to better sensitivity

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Stratospheric Observatory for Infrared Astronomy (SOFIA)

• SOFIA has 2.5m mirror.

• It has a variety of instruments (see below) covering optical to FIR.

• HAWK is being upgraded with new detectors and polarimeters.

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Herschel

• The Herschel telescope is a Cassegrain design with a 3.5m primary. The three scientific instruments are: – HIFI (Heterodyne Instrument for the

Far Infrared), a very high resolution heterodyne spectrometer

– PACS (Photodetector Array Camera and Spectrometer) - an imaging photometer and medium resolution grating spectrometer

– SPIRE (Spectral and Photometric Imaging Receiver) - an imaging photometer and an imaging Fourier transform spectrometer

• Covers 60-670 um.

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Planck

• The Planck telescope has an off-axis 1.5m primary. The scientific instruments are: – LFI (Low Frequency Instrument),

a High Electron Mobility Transistor based radio receiver.

– HFI (High Frequency Instrument), a bolometer based imaging array

• Covers 300um to 1.2cm.

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ALMA

• The Atacama Large Millimeter/submillimeter Array

• Covers 300um to a few cm

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Radio Telescope Components

• Reflector(s)

• Feed horn(s)

• Low-noise amplifier

• Filter

• Downconverter

• IF Amplifier

• Spectrometer

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Antenna Fundamentals

• An antenna is a device for converting electromagnetic radiation into electrical currents or vice-versa, depending on whether it is being used for receiving or for transmitting.

• In radio astronomy, antennas are used for receiving.

• The antenna receiver usually receives radiation from a dish, but it doesn’t have to.

• For instance, the Long Wavelength Array (LWA) that has ~104 dipoles. At a wavelength of 15m, the dipoles have ~106

m2 of effective collecting area, where collecting area goes as wavelength squared, divided by 4 pi.

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Very Large Array (VLA)

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VLA Main Features

• 27 radio antennas in a Y-shaped configuration

• fifty miles west of Socorro, New Mexico

• each antenna is 25 meters (82 feet) in diameter

• data from the antennas are combined electronically to give the resolution of an antenna 36km (22 miles) across

• sensitivity equal to that of a single dish 130 meters (422 feet) in diameter

• four configurations: – A array, with a maximum antenna separation of 36 km; – B array -- 10 km; – C array -- 3.6 km; and – D array -- 1 km.

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VLA Receivers

Receivers Available at the VLA

  4 Band P Band L Band C Band X Band U Band K Band Q Band

Frequency (GHz) 0.073-0.0745 0.30-0.34 1.34-1.73 4.5-5.0 8.0-8.8 14.4-15.4 22-24 40-50

Wavelength (cm) 400 90 20 6 3.6 2 1.3 0.7

Primary beam (arcmin) 600 150 30 9 5.4 3 2 1

Highest resolution (arcsec) 24.0 6.0 1.4 0.4 0.24 0.14 0.08 0.05

System Temp 1000-10,000.K 150-180.K 37-75.K 44.K 34.K 110.K 50-190.K 90-140.K

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Very Long Baseline Array (VLBA)

• ten radio telescope antennas– 25 meters (82 feet) in diameter and weighing 240 tons– Mauna Kea to St. Croix in the U.S. Virgin Islands

• VLBA spans more than 5,000 miles, providing astronomers with the sharpest vision of any telescope on Earth or in space.

• efforts to reduce funding

• efforts to increase sensitivity (~6x)

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Chandra

Chandra in Earth orbit (artist’s conception)http://chandra.nasa.gov/

Originally AXAFAdvanced X-ray Astrophysics Facility

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Chandra Orbit

• Deployed from Columbia, 23 July 1999

• Elliptical orbit– Apogee = 86,487 miles (139,188 km) – Perigee = 5,999 miles (9,655 km)

• High above LEO Can’t be Serviced

• Period is 63 h, 28 m, 43 s– Out of Earth’s Shadow for Long Periods– Longer Observations

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Chandra Mirrors Assembled and Aligned by Kodak in Rochester

“Rings”

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Mirrors Integrated into spacecraft at

TRW (NGST), Redondo Beach, CA

(Note scale of telescope compared to workers)

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Chandra ACIS CCD Sensor