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Good UNM Telescopes and the Evil Atmosphere

Good UNM Telescopes and the Evil Atmosphere. John McGraw. A Talk in the Universe of Good and Evil. The Obscure Universe The Good – Fundamental new capability to understand the universe Why we want excellent ground-based telescopes UNM Initiatives in Ground-based Astronomy

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Good UNM Telescopes and the Evil Atmosphere

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  1. Good UNM Telescopes and the Evil Atmosphere John McGraw

  2. A Talk in the Universe ofGood and Evil • The Obscure Universe • The Good – Fundamental new capability to understand the universe • Why we want excellent ground-based telescopes • UNM Initiatives in Ground-based Astronomy • The Evil – The Earth’s atmosphere interferes with ground-based optical/IR observations in a number of ways

  3. The Obscure Universe • Two causes of obscuration: • Physical obscuration – dust! • Inability to observe – observational blindness. • Simultaneous optical/infrared time-resolved synoptic observations

  4. The Obscure Universe • Discovery of Quasars • Quasar Lensing • AGN Reverberation

  5. The Obscure Universe • The Nature of Quasars

  6. The Obscure Universe • The “Standard Model” • Accretion disc scale ~ 1 pc

  7. The Obscure Universe • AGN phenomenon is ubiquitous • Milky Way? • All galaxies? • Evolution?

  8. The Obscure Universe • Mapping: Model, Orientation, Time History • Light travel timescale ~ 3 years • Dynamical timescale ~ r/V ~ 10 – 100 years

  9. The Obscure Universe • The outsider’s view of gravitational lensing:

  10. The Obscure Universe • Geometry of Different Optical paths • Source geometry • Lens geometry • Source dust chemistry • Well-sampled light curves • Optical path length measurement • Effects of microlensing • Dust in lenses

  11. The Obscure Universe • Luminosity variability • Days to years • Intrinsic variability • Optical path length • Microlensing • Colley et al. 2002

  12. The Obscure Universe • AGN Reverberation • Mapping the scale, structure, and time-dependent structure changes in the environs of massive black holes • Testing the standard model of AGNs • Examples: N1275, N7742

  13. The Obscure Universe • CTI • 1.8-m, f/2.2 meridian transit telescope • Images formed on multiple detectors operated in TDI mode • no moving parts • multiple colors each night • Fully automated operation • Photometric imaging over 1 - 2° FOV • surveys ~120°2 each night • V21.7 (S/N) > 5 nightly detection limit

  14. The Obscure Universe • Quasars • 1° wide strip, α = 8 hours (NGC)  120°² • 25 quasars/°² to B = 21  3000 quasars • Conservatism: 2° FOV, tilt to cover 10°, B fainter than 22 at S/N = 10, 2df data  all quasars • Galaxies (same geometry, B = 19.7) •  18000 galaxies • SNe (same geometry, B = 21 point source) •  100 ~ SNe/year

  15. The Obscure Universe • A UNM/UT collaboration can address many fundamental questions about the Obscure Universe. • First year of five funded by AFRL

  16. Extinction, Refraction and TurbulenceFrom Earth’s Atmosphere • The atmosphere is a turbulent, absorbing, refractive medium that must be considered part of the optical system of any telescope. • System design trade-offs: perhaps not too bad!

  17. Effects of Earth’s Atmosphere • Three layers in the Earth’s atmosphere contribute to turbulence • Surface layer • Planetary boundary layer • Upper atmosphere • We can do something about the surface layer!

  18. Effects of Earth’s Atmosphere • Refractive Index Structure Constant • Where: • P(h) is pressure in millibars • T(h) is temperature in Kelvin • h is height in meters • r is sensor separation in meters • p is position at h separated by r

  19. Effects of Earth’s Atmosphere • Microthermal testing • 1-m separation • Probes spaced in altitude • 250 Hz digital sampling

  20. Effects of Earth’s Atmosphere • Microthermal measurements • Sunrise neutral event • Convective/radiative transport

  21. Effects of Earth’s Atmosphere • Surface Layer Atmospheric Turbulence Differential Image Motion Monitor • SLAT-DIMM • Sources matched to sub-apertures • DIMM technique • Doesn’t assume atmospheric model • Provisional patent in progress

  22. Effects of Earth’s Atmosphere • LIDAR Saves Astronomy • Small, inexpensive lidar to monitor atmospheric transparency in real-time • “Engineering data stream” • Multiple use modes • NSF proposal – Georgia Tech

  23. Effects of Earth’s Atmosphere • Real-time pupil curvature measurements • Real-time image PSF measurements • Pupil phase reconstruction?

  24. Our Goals • Site selection for CTI • Help optimize HET • Transparency monitor (lidar) at CTI • Real-time image reconstruction • Access to telescopes for UNM • Investigate the Obscure Universe

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