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: Homework: Grading: HW 40% Project 20% Midterm 20% 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

SALT Telescope PIC: SALT outside now

WIYN Telescope

Total E/t= Luminosity, L Total L is bolometric luminocity. Should be able to derive lnew vs llambda using new=c/lambda Ln = specific luminosity

Flux L is a fundametally important quantity, but we cannot measure it on earth. Instead we measure 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

For small changes in flux

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 Where I will depend on: Omega measured in RA and Dec v= frequency t= Integration time P=polarization Location where you are receiving the light.

Observation E=energy received during measurement R=energy from the sky F= filter function Spectrometers try to make F as narrow as possible

1.1µ silicon bandgap 3100Å is the UV atmospheric cutoff