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Hubble Space Telescope Cutaway 1 Hubble Space Telescope Field of View • • • • • WFC3 ACS STIS COS FGS 2 HST: WFC3 3 HST: WFC3 4 HST: ACS 7 HST: ACS 8 HST: STIS 9 HST: STIS 10 Spitzer Space Telescope • • • IRAC IRS MIPS 11 Spitzer Space Telescope: IRAC 12 Spitzer Space Telescope: IRS 13 Spitzer Space Telescope: MIPS 14 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 15 Chandra Space Telescope: ACIS • Chandra Advanced CCD Imaging Spectrometer (ACIS) 16 Chandra Space Telescope: HRC 17 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. 18 Gemini (North) 19 Gemini (South) 20 JWST • • • NIRCAM NIRSPEC MIRI 21 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. 22 JWST: NIRSPEC • • • 1-5 um; R=100, 1000, 3000 3.4x3.4 arcminute field Uses a MEMS shutter for the slit 23 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. 24 JWST: MIRI MRS 25 NIRSPEC/Keck Optical Layout Side View NIRSPEC/Keck Optical Layout Top View Large CCD Mosaics 28 LSST Has a Big Camera 29 LSST Has a Big Focal Plane Wavefront Sensors (4 locations) Guide Sensors (8 locations) 3.5 degree Field of View (634 mm diameter) 30 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 31 Detector Size 32 Applications Imaging (single photon counting) Figures Courtesy of Don Hall (University of Hawaii) 33 Fermi Gamma-ray Large Area Space Telescope (GLAST) 34 GLAST LAT 35 Gamma Ray Detection Airshowers • It is possible to detect gamma rays by the presence of their byproducts 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. 36 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 37 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. 38 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. 39 Planck • The Planck telescope has an offaxis 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. 40 ALMA • The Atacama Large Millimeter/submillimeter Array • Covers 300um to a few cm 41 Radio Telescope Components • • • • • • • Reflector(s) Feed horn(s) Low-noise amplifier Filter Downconverter IF Amplifier Spectrometer 42 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. 43 Very Large Array (VLA) 44 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. 45 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 1000-10,000.K 150-180.K 37-75.K 44.K 34.K 110.K 50-190.K 90-140.K System Temp 46 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) 47 Chandra Originally AXAF Advanced X-ray Astrophysics Facility http://chandra.nasa.gov/ Chandra in Earth orbit (artist’s conception) 48 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 49 Chandra Mirrors Assembled and Aligned by Kodak in Rochester “Rings” 50 Mirrors Integrated into spacecraft at TRW (NGST), Redondo Beach, CA (Note scale of telescope compared to workers) 51 Chandra ACIS CCD Sensor 52