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Modern Observational/Instrumentation Techniques Astronomy 500. Andy Sheinis, Sterling 5520,2-0492 sheinis@astro.wisc.edu MW 2:30, 6515 Sterling Office Hours: Tu 11-12. Class Website: Handouts, .ppt lectures and HW will be posted http://www.astro.wisc.edu/~sheinis/~500class. Homework:
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Modern Observational/Instrumentation TechniquesAstronomy 500 Andy Sheinis, Sterling 5520,2-0492 sheinis@astro.wisc.edu MW 2:30, 6515 Sterling Office Hours: Tu 11-12
Class Website: Handouts, .ppt lectures and HW will be posted http://www.astro.wisc.edu/~sheinis/~500class Homework: There will be a 5-6 problem sets, one due approximately every other week. I will either post, or handout solutions. I encourage you to discuss the problems with your classmates, but you must each write up your own solution. There will also be a Midterm and Final exam as well as an “Observational” project, which may or may not include a laboratory exercise. Grading: Approximate grading distribution will be: HW 40% Project 20% Midterm 20% Final 20%
Texts: Required: Walker, "Astronomical Observations", Cambridge Univ. Press. Schroeder, "Astronomical Optics", Academic Press Recommended: Kitchin, "Astrophysical Techiques", Adam Hilger, Ltd Bevington&Robinson, "Data Reduction and Error Analysis for the Physical Sciences", McGraw-Hill Gray, “The Observation and Analysis of Stellar Photospheres”, Cambridge U. Press Other Useful References: McLean, “Electronic Imaging in Astronomy”, Wiley Rybicki and Lightman, “Radiative Processes in Astrophysics”, Wiley Cox, “Allen’s Astrophysical Quantities”, Athlone Press
Astronomy is Different • Universe is the laboratory • We can only observe, no interaction • Limited to phenomena, occuring in the past • Must take interpret a “snapshot” • Have only the properties of light • Cannot measure directly, must infer from the measurement of light.
Properties of light • Intensity, flux, irradiance, amplitude • Angle of arrival, position, image • Wavelength, frequency, color • Angular momentum, spin, polarization • time variation (in some cases) • Phase (interferometry, radio, AO)
LargeTelescopes • Only two (Keck I and II) available in the 90’s • Several available at the turn of the century (the 4 VLT units, Gemini North and South, Subaru, HET) • One more in 2005, SALT! • others under construction (LBT, GTC) • and plans already for 30-100m telescopes...
Telescopes • Name Diameter Nationality of Sponsors Site Built • (SALT) 11.0 m South Africa, USA, UK, Germany, Poland, New Zealand South African 2005 • (GTC) 10.4 m Spain Roque de los Muchachos Observatory, Canary Islands 2005 • Keck 1 9.8 m USA Mauna Kea Observatory, Hawaii 1993 • Keck 2 9.8 m USA Mauna Kea Observatory, Hawaii 1996 • (HET) 9.2 m USA, Germany McDonald Observatory, Texas 1997 • (LBT) 2x8.4 m USA, Italy, Germany Mount Graham Arizona 2004 • Subaru (NLT) 8.3 m Japan Mauna Kea Observatory, Hawaii 1999 • VLT 1 (Antu) 8.2 m ESO Countries (European + Chile) Paranal Observatory, Chile 1998 • VLT 2 (Kueyen) 8.2 m ESO Countries (European + Chile) Paranal Observatory, Chile 1999 • VLT 3 (Melipal) 8.2 m ESO Countries (European + Chile) Paranal Observatory, Chile 2000 • VLT 4 (Yepun) 8.2 m ESO Countries (European + Chile) Paranal Observatory, Chile 2001 • Gemini North 8.1 m USA, UK, Canada, Chile, Australia, Mauna Kea Observatory, Hawaii 1999 • Gemini South 8.1 m USA, UK, Canada, Chile, Australia, Cerro Tololo Observatory, Chile 2001 • (MMT) 6.5 m USA Fred Lawrence Whipple Observatory, Arizona 1999 • Magellan 1 6.5 m USA Las Campanas Observatory, Chile 2000 • Magellan 2 6.5 m USA Las Campanas Observatory, Chile 2002 • BTA-6 6 m Russia Zelenchukskaya, Caucasus 1976 • Large Zenith Telescope (LZT) 6 m Canada, France Maple Ridge, British Columbia 2003 • Hale Telescope 5 m USA Palomar Observatory, California 1948
PIC: SALT outside now SALT Telescope
Total E/t= Luminosity, L Ln = specific luminosity
Flux Flux is energy incident on some area dA of the Earths surface. Flux is not conserved and falls of as R-2.
Flux • Flux is measured in Janskys in the radio • 1Jy=10-26 W m-2 Hz-1 • In the visible flux is measured in apparent magnitudes
Flux: absolute magnitude • Absolute magnitude is the apparent magnitude that would be observed at 10 pc. • A is the total extinction due to intersetllar dust in magnitudes
Standard choices for reference flux • Vega system: apparent Magnitude of Vega = 0 in all bands. • Convenient, but non-physical • A-B magnitude system: • F0=3.63e10-23 W m-2 Hz-1, flat spectrum • Agrees with Vega at 548nm (center of V-band)
Interesting magnitudes (V-band) • Sun: m=-26.7 • Full moon: m=-12.6 • Sirius: m=-1.5 • Naked eye limit: m=6 • Brightest stars in Andromeda: m=19 • Present day limit: m~29 • Night sky: m=21.5 (best sites, dark time) • Night sky: m=18 (bright time)
Intensity • Finite size source (subtends a real angle) • Specific intensity • Brightness, surface brightness • Specific brightness • Units: (Jy sr-1) or (W m-2 Hz-1sr -1) or (erg cm-2 Hz -1) or (m arcsec-2) • What happens when the source is not resolved?
Intensity • Omega measured in RA and Dec • v= frequency • t= Integration time • P=polarization • Location where you are receiving the light. Where I will depend on:
Observation • E=energy received during measurement • R=energy from the sky • F= filter function
1.1µ silicon bandgap 3100Å is the UV atmospheric cutoff