the chara array - georgia state university chara array center for high angular resolution astronomy...

CHARA Community Workshop 2017-03-15

The CHARA Array

Theo ten BrummelaarDirector

The CHARA ArrayCenter for High Angular Resolution

AstronomyMount Wilson Observatory

Georgia State University


• The resolving power of a telescope increases

as the telescope diameter increases.

• The light gathering power also increases with

telescope diameter.

• Unfortunately the atmospheric distortion and

engineering problems do too.

• We can get around some of these problem by

using many smaller telescopes spread out

over a large area.


Anaheim - 23 Jan 99 Interferometry on Mt. Wilson 4

Beam Combining EssentialsBeam Combining Essentials

to Star

Tel. #2Tel. #1

StarlightStarlight

“Baseline” B

“Delay”

B sin

Delay CompensatorFringe Position


Effect of Increasing Angular Diameter a

a = 0.50 mas

0 50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

1

1.771 1010

V2 B( )

299.970.01 B

Baseline (meters)

0 50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

1

4.859 1010

V2 B( )

299.970.01 B

0 50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

1

1.549 1012

V2 B( )

299.970.01 B

0 50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

1

2.496 1010

V2 B( )

299.970.01 B

0 50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

1

1.928 1010

V2 B( )

299.970.01 B

0 50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

1

6.321 1011

V2 B( )

299.970.01 B

0 50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

1

7.099 1011

V2 B( )

299.970.01 B

Visibility 2

a = 1.0 mas a = 1.5 mas a = 2.5 mas a = 5.0 mas a = 0.55 mas a = 0.75 mas


Effect of Increasing rr = 0.1 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

Visibility 2

Baseline (meters)

r = 0.2 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity

Sq

ua

red

r = 0.3 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

r = 0.5 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

r = 0.75 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

r = 1.0 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

r = 1.5 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

r = 2.0 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity

Sq

ua

red

r = 3.0 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity

Sq

ua

red

r = 5.0 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

r = 10 mas

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity

Sq

ua

red

a1 = a2 = 1.0 mas; Dm = 0


Effect of Increasing Dm

Baseline (meters)

Visibility 2

Binary System with Dm = 0

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

Binary System with Dm = 0.25

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity

Sq

ua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity

Sq

ua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity

Sq

ua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red


0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

Binary System with Dm = 10

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

Baseline

Vis

ibil

ity S

qua

red

a1 = a2 = 1.0 mas; r = 2.5 mas


10000 km

VLBA spans the Earth

and has the highest

angular resolution

of any observatory


1000 km Zoom x10


100 km Zoom x100


10 km Zoom x1000


1 km Zoom x10000By using NIR and Visible light instead of radio waves, we can achieve the

same angular resolution as VLBA but with a much smaller interferometer


Layout of the CHARA Array


Overall Optical Layout


Telescopes

CAD by Laszlo

Sturmann

~6

ft

Photo by Steve

Golden


Vacuum Light Tubes

Feed Light from Each Telescope to the

Central Lab


Optics Laboratory

Delay Lines

Beam

Reducing

Telescopes

Dispersion

Correction Beam

Sampler

Beam

Combing

Laboratory


The 30 second CHARA tour.


CLIMB: CLassic Interferometry on

Multiple Baselines


FLUOR: Fiber Linked Unit for Optical

Recombination


What is PAVO (besides Spanish for

Turkey) ?• PAVO is an integral-field-unit for measuring spatially-modulated pupil-

plane fringes.

• PAVO combines three beams for closure phase and has the highest

sensitivity of all instruments in the visible wavebands.

• PAVO has been completed at CHARA and, weather pending, will be

comissioned at SUSI next week.


VEGA: Visible spEctroGraph and

polArimeter• Highest spectral resolution in the

visible (R=30000).

• Combines up to four beams

• Uses a combination of Single Slit

Spectroscopy, Speckle Interferometry

and “Real” Interferometry.


MIRC: Michigan InfraRed beam Combiner

Making Real Images


AROC

2002

ROCN

2008

ROCS

2008

ROCMI

2006

ROCME

2004

ROCME

2012


Youn

g St

ellar

Obje

cts w

ith D

isks

(Dec

linat

ion >

-25

degs

)

45

67

89

10H

mag

nitud

e

6810121416

R magnitude

Annu

al M

edian

See

ing C

ondit

ions

r0~7

cm

45

67

89

10H

mag

nitud

e

6810121416

R Magnitude

CHAR

ACu

rrent

Per

form

ance

13 T

arge

ts

CHAR

Awi

th fu

ll AO

46 T

arge

ts

CHARA-AO Program – New Capabilities


The Phase II Money Plot…

Good seeing 75% of

the time, rather than

25% resulting in 3

times more high

quality observing

time.

One magnitude of

increased sensitivity

25%75% 50%


CHARA-AO Phase I: Telescopes


CHARA-AO Phase I: LABAO


CHARA-AO Control


CHARA-AO Phase II: Telescopes

Phase II

funds

replacing

M4 with a

deformable

mirror at

each

telescope.

This will

enable us to

correct for

atmospheric

seeing and

increase

scientific

throughput.


The U.S. lags Europe in access to, support of, and

education about OIR Interferometry


NOAO Observing : https://www.noao.edu/gateway/chara/


More exciting times are

ahead….

the chara array - georgia state university chara array center for high angular resolution astronomy...

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