Good UNM Telescopes and the Evil Atmosphere John McGraw.

Good UNM Telescopes and Good UNM Telescopes and the Evil Atmospherethe Evil Atmosphere

John McGrawJohn McGraw

A Talk in the Universe ofA Talk in the Universe ofGood and EvilGood and Evil

The Obscure UniverseThe Obscure Universe The Good – Fundamental new capability to The Good – Fundamental new capability to

understand the universeunderstand the universe Why we want excellent ground-based telescopesWhy we want excellent ground-based telescopes

UNM Initiatives in Ground-based AstronomyUNM Initiatives in Ground-based Astronomy The Evil – The Earth’s atmosphere interferes with The Evil – The Earth’s atmosphere interferes with

ground-based optical/IR observations in a number ground-based optical/IR observations in a number of waysof ways

The Obscure UniverseThe Obscure Universe Two causes of obscuration:Two causes of obscuration:

Physical obscuration – dust!Physical obscuration – dust! Inability to observe – observational blindness.Inability to observe – observational blindness.

Simultaneous optical/infrared time-Simultaneous optical/infrared time-resolved synoptic observationsresolved synoptic observations

The Obscure UniverseThe Obscure Universe

Discovery of Discovery of QuasarsQuasars

Quasar LensingQuasar Lensing

AGN AGN ReverberationReverberation


The Nature of The Nature of QuasarsQuasars


The “Standard Model”The “Standard Model” Accretion disc scale ~ 1 pcAccretion disc scale ~ 1 pc


AGN phenomenon AGN phenomenon is ubiquitousis ubiquitous Milky Way?Milky Way? All galaxies?All galaxies? Evolution?Evolution?


Mapping: Model, Orientation, Time HistoryMapping: Model, Orientation, Time History Light travel timescale ~ 3 yearsLight travel timescale ~ 3 years Dynamical timescale ~ r/V ~ 10 – 100 yearsDynamical timescale ~ r/V ~ 10 – 100 years


The outsider’s view The outsider’s view of gravitational of gravitational lensing:lensing:


Geometry of Geometry of Different Optical Different Optical pathspaths Source geometrySource geometry Lens geometryLens geometry Source dust chemistrySource dust chemistry

Well-sampled light Well-sampled light curvescurves Optical path length Optical path length

measurementmeasurement Effects of microlensingEffects of microlensing Dust in lensesDust in lenses


Luminosity Luminosity variabilityvariability Days to yearsDays to years

Intrinsic variabilityIntrinsic variability Optical path lengthOptical path length MicrolensingMicrolensing

Colley et al. 2002Colley et al. 2002


AGN ReverberationAGN Reverberation Mapping the scale, structure, and Mapping the scale, structure, and

time-dependent structure changes time-dependent structure changes in the environs of massive black in the environs of massive black holesholes

Testing the standard model of AGNsTesting the standard model of AGNs Examples: N1275, N7742Examples: N1275, N7742


CTICTI 1.8-m, f/2.2 meridian 1.8-m, f/2.2 meridian

transit telescopetransit telescope Images formed on Images formed on

multiple detectors multiple detectors operated in TDI modeoperated in TDI mode

no moving partsno moving parts multiple colors each nightmultiple colors each night

Fully automated operationFully automated operation Photometric imaging over Photometric imaging over

1 - 2° FOV1 - 2° FOV surveys ~120°surveys ~120°22 each each

nightnight VV21.7 (S/N) > 5 nightly 21.7 (S/N) > 5 nightly

detection limitdetection limit


QuasarsQuasars 1° wide strip, 1° wide strip, αα = 8 hours (NGC) = 8 hours (NGC) 120°² 120°² 25 quasars/°² to B = 21 25 quasars/°² to B = 21 3000 quasars3000 quasars

Conservatism: 2° FOV, tilt to cover 10°, B fainter than Conservatism: 2° FOV, tilt to cover 10°, B fainter than 22 at S/N = 10, 2df data 22 at S/N = 10, 2df data all quasars all quasars

Galaxies (same geometry, B = 19.7)Galaxies (same geometry, B = 19.7) 18000 galaxies18000 galaxies

SNe (same geometry, B = 21 point source)SNe (same geometry, B = 21 point source) 100 ~ SNe/year100 ~ SNe/year


A UNM/UT collaboration can A UNM/UT collaboration can address many fundamental address many fundamental questions about the questions about the Obscure Obscure UniverseUniverse..

First year of five funded by First year of five funded by AFRLAFRL

Extinction, Refraction and Extinction, Refraction and TurbulenceTurbulence

From Earth’s AtmosphereFrom Earth’s Atmosphere The atmosphere is a The atmosphere is a

turbulent, absorbing, turbulent, absorbing, refractive medium refractive medium that must be that must be considered part of considered part of the optical system of the optical system of any telescope.any telescope. System design trade-System design trade-

offs: perhaps not too offs: perhaps not too bad!bad!

Effects of Earth’s Effects of Earth’s AtmosphereAtmosphere

Three layers in the Earth’s atmosphere contribute to turbulenceThree layers in the Earth’s atmosphere contribute to turbulence Surface layerSurface layer Planetary boundary layerPlanetary boundary layer Upper atmosphereUpper atmosphere

We can do something about the surface layer!We can do something about the surface layer!


)()(

)(1080)( 22

2

62 hC

hThPhC Tn

Refractive Index Refractive Index Structure ConstantStructure Constant

Where:Where: P(h) is pressure in millibarsP(h) is pressure in millibars T(h) is temperature in KelvinT(h) is temperature in Kelvin h is height in metersh is height in meters r is sensor separation in metersr is sensor separation in meters p is position at h separated by rp is position at h separated by r

221 )()(),( pTpThrDT

3/22 )(),( rhChrD TT


Microthermal testingMicrothermal testing 1-m separation1-m separation Probes spaced in Probes spaced in

altitudealtitude 250 Hz digital 250 Hz digital

samplingsampling


Microthermal Microthermal measurementsmeasurements Sunrise neutral eventSunrise neutral event Convective/radiative transportConvective/radiative transport


Surface Layer Atmospheric Surface Layer Atmospheric Turbulence Differential Image Turbulence Differential Image Motion MonitorMotion Monitor SLAT-DIMMSLAT-DIMM

Sources matched to sub-aperturesSources matched to sub-apertures DIMM techniqueDIMM technique Doesn’t assume atmospheric modelDoesn’t assume atmospheric model

Provisional patent in progressProvisional patent in progress

0 50 100 150 200 2500

0.02

0.04

0.06

0.08

0.1

0.12

0.14

t (sec)

Me

an

RM

S i

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Heat source shut off hereAdded turbulence from

lab personnel

Heat source on

Heat source off Image Motion dominated by centroid noise


LIDAR Saves AstronomyLIDAR Saves Astronomy Small, inexpensive lidar Small, inexpensive lidar

to monitor atmospheric to monitor atmospheric transparency in real-timetransparency in real-time

““Engineering data Engineering data stream”stream”

Multiple use modesMultiple use modes NSF proposal – Georgia NSF proposal – Georgia

TechTech


Real-time pupil Real-time pupil curvature curvature measurementsmeasurements

Real-time image Real-time image PSF measurementsPSF measurements

Pupil phase Pupil phase reconstruction?reconstruction?

Our GoalsOur Goals Site selection for CTISite selection for CTI Help optimize HETHelp optimize HET Transparency monitor Transparency monitor

(lidar) at CTI(lidar) at CTI Real-time image Real-time image

reconstructionreconstruction Access to telescopes Access to telescopes

for UNMfor UNM Investigate the Investigate the

Obscure UniverseObscure Universe

Good UNM Telescopes and the Evil Atmosphere John McGraw.

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Transcript of Good UNM Telescopes and the Evil Atmosphere John McGraw.