glenn schneider steward observatory, university of arizona (nicmos/idt) coronagraphy with hst/nicmos...

Glenn Schneider Glenn Schneider Steward Observatory, University of Arizona (NICMOS/IDT)Steward Observatory, University of Arizona (NICMOS/IDT)

Coronagraphy with HST/NICMOSCoronagraphy with HST/NICMOS**

*The *The NNear ear IInfrared nfrared CCamera & amera & MMulti-ulti-OObject bject SSpectrometerpectrometerExtending HST’s UV/Optical Panchromatic VisionExtending HST’s UV/Optical Panchromatic Vision

into the Near IR (0.8into the Near IR (0.8m —2.m —2.m)m)

http://nicmosis.as.arizona.edu:8000

[email protected]

Hubble Space TelescopeHubble Space TelescopeThird Calibration WorkshopThird Calibration Workshop

18 October 200218 October 2002Baltimore, MarylandBaltimore, Maryland

• Diffraction Limited Imaging in Optical/Near-IR•> 98% Strehl Ratios @ alls• Highly STABLE PSF

NIR High Dynamic Range Sampling NICMOS/MA: mag=19.4 (6 x 4m)

• Intra-Orbit Field Rotation

NICMOS Coronagraphy Takes Advantage of HST’sNICMOS Coronagraphy Takes Advantage of HST’s Unique Venue for High Contrast ImagingUnique Venue for High Contrast Imaging

Background Rejection*Background Rejection*1.61.6m: ~10m: ~10-6-6 pix pix-1 -1 @ 1”@ 1”

1.11.1m: ~10m: ~10-5 -5 in 2”-3” annulusin 2”-3” annulus

*w.r.t. central pixel*w.r.t. central pixel FFcentralcentral(H) = 11% F(H) = 11% Fstarstar

• Highly Accurate Pointing Repeatability & Control

Scientific Areas of Investigation EnabledScientific Areas of Investigation EnabledWith Today’s Capabilities on HSTWith Today’s Capabilities on HSTvia PSF-Subtracted Coronagraphic Imagingvia PSF-Subtracted Coronagraphic Imaging

Damped L Absorbers LBQS 1210+1713

Young Extra-Solar Planet* &Brown Dwarf Companions

* < few x 106 yr at 1”

2.5"TWA 6

Circumstellar Disksfdisk/f*

> few x 10-4 at 1”

0.1”

1"

HR 4796A

0

6 7 8 9 10Log10 Age (years)

80Mjup

14Mjup

JUPITER

SATURN

STARS (Hydrogen burning)

BROWN DWARFS (Deuterium burning)

PLANETS

200Mjup

Evolution of M Dwarf Stars, Brown Dwarfsand Giant Planets (from Adam Burrows)

-10

-8

-6

-4

-2

Cooling Curves for Substellar ObjectsCooling Curves for Substellar Objects

Log L/L(sun)

system,

Primary Dust (≤ m) Secondary Dust (≥Locked to Gas Collisional erosion

Clearing Timescales: P-R drag few 10 Rad. Pressure: ~ 10

From: R. Webb

m)

64

Terrestrialplanets

form

Clearing ofinner solar

formation of aKuiper

cometarybelt?

Rocky coresof giant

planets form

108

yrs109

yrs

PerseiSun

HyadesTucanaeAssoc Pleiades

106

yrs

Taurus,Ophiuchus

star formingregions

TW Hydrae

ry s107

Assoc

Era of heavybombarment

by comets

Currentage of

the Sun:5x109 yrs.

Collapsingprotostar

forms proto-planetary disk

accretegaseous

atmospheres

Giant planets

Planet-Building TimelinePlanet-Building Timeline

Disk Evolution/Dissipation(?)

Coronagraphic Companion DetectionCoronagraphic Companion DetectionPSF “Roll Subtraction”PSF “Roll Subtraction”

HD 102982H = 6.9

G3V

H = 5.3 = 0.9"

(Multiaccum) Imaging at two S/C orientations in a single HST visability period. Background objects rotate about occulted Target. PSF and optical artifacts do not.

Roll = 30°, Time ≈ 20 min., Total time per Orientation ≈ 11 min.Combined detection floor in absence of background light: H ≈ 23

C o r o n a g r a p h ic I m a g e s

O r ien tatio n =3 0 °

D if f er en ceI m age

S ep ar atein toP osit iv e

& N egativ eC o n j u gates

R o tateab ou tH o le

C en ter an d C o -A d d

(R esam p led )

Combined detection floor in absence of background light: H ≈ 23

H = 21.9 = 9.36”H = 12.6

H = 22.3 = 13.34”H = 12.9

LHS 3003H = 9.3

TA Persistence Ghost Images

.

Radius (Arcsec) from Hole Center

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5 1.65 1.8 1.95 2.1 2.25 2.4 2.55 2.7 2.85

Radius (Pixels) from Hole Center

0 0.075 0.15 0.225 0.3 0.375 0.45 0.525 0.6 0.675 0.75 0.825 0.9 0.975 1.0510-6

10

10-4

10-3

10-2

10-1

100 REDUCTION IN BACKGROUND FLUX FROM F160W PSF

ARCSECONDS

CoronagraphicHole

Radius = 0.3"

1pixel

-5

Unocculted PSFCoronagraphCoronagraph & PSF Subtraction

BACKGROUND

REDUCTION

Coronagraphic Performance (G2V)Coronagraphic Performance (G2V)

w.r.t. central pixelw.r.t. central pixel FFcentralcentral(H) = 11% F(H) = 11% Fstarstar

General DescriptionGeneral DescriptionCoronagraphic Field of ViewCoronagraphic Field of View

• NICMOS Coronagraph is in Camera 2*: 256 x 256 pixels @ ~ [76.2, 75.5] mas / pixel FOV ~ 19.49” x 19.33” (377 ”) 0.9% X:Y Linear Geometrical Distortion

• Radius of Occulted Region = 0.3” Size “Optimized” for H-band Imaging (1st Airy Ring fully contained) ~ [+73, -45] pixels (or [+5.6”, -3.4”] from [-X,+Y] corner of FOV

• Field Asymetric w.r.t Occulted Star For maximum S/C Roll (at one epoch) of 29.9°: 475 ” Survey Area with 280 ” Overlap Area

* http://www.stsci.edu/hst/nicmos/performance/platescale/rel_platescale.html

Two Integrations from Median of 3 Multiaccums EachTotal Integration Time = 640 seconds at Each Orientation

Roll = 30°, Time = 20 minutes

Linear Display 0—20 ADU/sec/pixel; 2.19E-6 Janskys/ADU/sec/pixel


EXAMPLE: TWA 6, H = 6.9

Linear Display 0—2 ADU/sec/pixel; 2.19E-6 Janskys/ADU/sec/pixel

Coronagraphic Companion DetectionCoronagraphic Companion Detection

Unresolved (Point-Like) Object: H =20.1, H = 13.2, =2.5”

Linear Display -0.4 — +0.4 ADU/sec/pixel; 2.19E-6 Janskys/ADU/sec/pixel


Difference Image: H =20.1, H = 13.2 (La/Lb = 200,000:1), =2.5”

At =2.5” background brightness is reduced by an ADDITIONAL factor of ~50 over raw coronagraphic gain (of appx 4).

Linear Display -0.4 — +0.4 ADU/sec/pixel; 2.19E-6 Janskys/ADU/sec/pixel


Each independent point-source image is S/N ~ 20

Geometrical RectificationAnd De-Spiking*

*NICMOS/IDT Post-Processing & Analysis S/W: DSKP & IDP3ftp://nicmos.as.arizona.edu/


A spatial filter is applied tothe combined image to furtherreject image artifacts with characteristic frequenciesnot commensurate with thesize of a stellar PSF.

0.01.02.0 1.0 2.0Arc Seconds

PSF FWHM = 0.16"

NICMOSF160W25 OCT 1998

Camera 2 (0.076"/pixel)Coronagraph (0.3" radius)Integration Time =1280s

Image Combination& Spatial Filtering

“Final” Image After Additional Post-Processing

S/N ~ 35

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5 6Radius (Pixels)

TWA6

Sensitivity (S/N=25) vs. Detectability (50% Probability*)Sensitivity (S/N=25) vs. Detectability (50% Probability*)

H-Band Two-Roll Coronagraphic PSF Subtraction 22m Total Integration

H(50%) = 9.7±0.3 + 2.1 x {M–G Stars}

TWA6TWA6 and and Median of 50 G-K Stars in NICMOS SurveyMedian of 50 G-K Stars in NICMOS Survey..

9

1 0

1 1

1 2

1 3

1

1 5

1 6

1 2 3 5R d i istnce(Acseconds)

Delta-H

* Determined by Noise Statistics AND Model Star Implantation* Determined by Noise Statistics AND Model Star Implantation

PRELIMINARYPRELIMINARY Post SM-3B Coronagraphic Performance Post SM-3B Coronagraphic Performance Characterization for HST Cycle 11/12Characterization for HST Cycle 11/12

Data from SMOV3B Test Programs:

• Coronagraphic Target Acquisition Test*

• Coronagraphic Focus Verification*

• Initial (Part 1) Performance Check - Characterization†

*Executed Prior to “Final” Plate Scale / Aperture Rotation Updates †Executed Prior to Low Scatter Point Determination / Adjustment

To Be Executed (Next Week) Under Cycle 11 Cal Program

• Coronagraphic Light-Scatter Minimization • “Final” (Part 2) Performance Check - Calibration

0 — +2.0 ADU/sec/pixel2.19E-6 Jy/ADU/sec/pixel

Coronagraphic First Light Post-SM3BCoronagraphic First Light Post-SM3B““Out of the Box” Out of the Box”

CYCLE 7GTO/7227

CYCLE 11SMOV3B/8983

0 — +2.75 ADU/sec/pixel1.59E-6 Jy/ADU/sec/pixel

-0.4 — +0.4 ADU/sec/pixel2.19E-6 Jy/ADU/sec/pixel

-0.55 — +0.55 ADU/sec/pixel1.59E-6 Jy/ADU/sec/pixel

CYCLE 7GTO/7227

CYCLE 11SMOV3B/8983

Coronagraphic First Light Post-SM3BCoronagraphic First Light Post-SM3B““Out of the Box” Out of the Box”

10-8

10-7

10-6

10-5

10-4

10-3

10 20 30 40 50

CoronagraphicDirect (Total = 23700 ADU/sec)

Radius (Pixels)

0

5

10

15

20

25

Direct/Coronagraphic

Coronagraphic Performance (M9.5V+)Coronagraphic Performance (M9.5V+)

Direct Coronagraphic

F160W

Coronagraphic PSF-Subtraction Induced Image ArtifactsCoronagraphic PSF-Subtraction Induced Image ArtifactsThe Dominant Source of Systematic Error (“Noise”)The Dominant Source of Systematic Error (“Noise”)**

Imperfections in PSF-subtractionsresult in residuals larger thanexpected from pure photon noise.

Systematics:

OTA “Breathing”

Target Re-centration

Coronagraphic Hole Edge Effects

Cold-Mask “Wiggles”

Opto-Mechanical Stability

*For properly reduced/calibrated

images

““Breathing” - The Coronagraphic Nemesis Breathing” - The Coronagraphic Nemesis

De-spaceing of the HST secondary mirror along the telescope optical axis from (orbit driven) thermal instabilities in the OTA causes variations in the PSF structures which are typically THE dominant source of systmatic errors in coronagraphic PSF subtraction.

The thermal time constant of the OTA is longer than sub-orbit timescales.

“Two roll” coronagraphic observations should be completed in a single target visibility period to minimize PSF variations.

Reference PSFs should be obtained as close in time (very preferabley in the same visibility period) as target images WITHOUT any intervening changes in Sun angle.

• Coronagraphic “Hole” On Camera 2 Field Divider Mirror @ OTA f/24 Focus Physical Radius: 170m Projected Radus: 0.3”

• Lyot Stop (85% Unobscured Area) At Cold Pupil in VCS (near Filters) Obscurations for (warm): Primary Mirror Outer Edge Secondary Mirror Housing Primary Mirror Hold-Down Pads

Coronagraphic Optics General DescriptionCoronagraphic Optics General Description

F160W PSF “Mapped” Onto Coronagraphic HoleF160W PSF “Mapped” Onto Coronagraphic Hole

A small change in energy distribution in the first Airy ring (due tobreating induced focus shifts) cause scattering sites on the hole-edgeto “light up” and change, significantly, the downstream scattering.

A Few Words on Circumstellar Disks…

Direct ImageDirect Image

HH30 ObscuredHH30 Obscured

Observing young circumstellar disksWith obscured central stars is not difficult.

Disk systems with unembedded, or onlymarginally obscured central stars aremuch more observationally challengingand require PSF-subtracted coronagraphy.

GM AUR Unembedded (AGM AUR Unembedded (Avv < 0.5) < 0.5)

Coronagraph +Coronagraph +PSF SubtractionPSF Subtraction

J* = 0.33 JyH* = 0.40 Jy

Red Polar Lobes10 Jy arcsec-2

Lower Scattering Surface0.2 mJy arcsec-2

Faint Blue Ribbon

For Disk Imaging, to Minimize Image Artifacts Resulting from Reference Subtraction, Reference PSFs Should Be:

• Obtained in the same visability period as the target whenever possible • Of Similar Spectral Type (Within One Spectral Class) • At Least as Bright as The Target

HR 4796AHR 4796A

For Disk Imaging, to Minimize Image Artifacts Resulting from Reference Subtraction, Target Images Should Be

• Obtained at Two or More Spacecraft Roll Orientations

TW HYDRAE HD 141569ATW HYDRAE HD 141569A

Calibrating Coronagraphic DataCalibrating Coronagraphic DataBe Critical of “Pipeline” ResultsBe Critical of “Pipeline” Results

Performance Levels Discussed ASSUME Properly Calibrated DataPerformance Levels Discussed ASSUME Properly Calibrated Data

Local and Global Deviations from True Photometric BackgroundsLocal and Global Deviations from True Photometric BackgroundsMUST Be Corrected (Zeroed) Before PSF-Subtraction, Otherwise:MUST Be Corrected (Zeroed) Before PSF-Subtraction, Otherwise:

Loss of Sensitivity (Against Residual Background)

Degraded Detectability in PSF-Subtracted Images

Photometric Zero-Point Errors

Spatial Non-Uniformity in Detection Limits

REFERENCE FLATS:

- Hole “imprint” in CDBS flats is static, in reality it moves. Augment Reference Flats with Contemporaneous TA Lamp Flats.


REFERENCE DARKS: See Silverstone Poster (This Workshop)

- “Synthetic” (Decomposed Models) Generated by OTFR vs. - Median Observed vs. - Combined (Temperature & SAA Decay) Selected

- Construct Reference Flats So As Not To Rely on Assumed High Fidelity of Knowledge of Linearity Transfer When Approaching Saturation. I.e., “throw away” reads > 50—70% full well when making reference flats.

Three Day “Snapshot”Of Coronagraphic Hole

Motion

OTFR/CALNIC10 October 2002Using “Best” Ref Data

CALNICA ANALOG(+ Bad Pixel Replacement)ObsDARKS/LinFLATS


Flat-Field ImprintNon-Zero Background

Quadrant Offsets“Photometrically Challenged” ColumnDead, Grotty, Excessively Hot Pixels

Or…Post-Processing Tools Exist To Mitigate

Calibration Errors, But Often Do Not Work Well In Regions of High Flux Densities and Large Signal Gradients


Progressively “Better” Flat-Field / Zero-Point Calibration Sequentially Through the Orbit Is a Tell-Tale Sign of A DC Offset Matching Problem.

OTFR/CALNIC 10 October 2002 Using “Best” Ref Data

OTFR/CALNIC10 October 2002Using “Best” Ref Data

CALNICA ANALOG(+ Bad Pixel Replacement)ObsDARKS/LinFLATS

Post-Processing to RemoveElectronic Image Artifacts:Saturation Bands & Echos


““Mode 2” Target Acquisition (TA)Mode 2” Target Acquisition (TA)

Target Blind-Pointed into 128x128 Pixel Acquisition Sub-Array Allowing for GSC errors co-ordinates must be known to ± 3.8” Central region of TA field-of-regard nearly free of detector defects.

CYCLE 11 BRIGHT OBJECT LIMIT: H = 4.0*

*Using F187N (1%) filter

TA Performance Verified: SMOV 8979

CYCLE 11 FAINT OBJECT LIMIT: H ~ 18* *Acquisition in one orbit, imaging in subsequent orbit(s)

““Mode 2” Target Acquisition (TA)Mode 2” Target Acquisition (TA)Cycle 11 (77K) Exposure Time Requirements (F160W)Cycle 11 (77K) Exposure Time Requirements (F160W)

TA Images with S/C Pointing & Acquisition (“Engineering”) Data Provide Necessary Information to Accurately Determine Occulted Target Position AFTER Offset Slew Maneuver

““Mode 2” Target Acquisition (TA)Mode 2” Target Acquisition (TA)ASTROMETRIC ANCHOR (Where is My Target?)ASTROMETRIC ANCHOR (Where is My Target?)

May Need to Correct “Requested” vs. Actual Post-Slew Target Position Due to Secular Change(s) in Image Scale and/or Aperture Rotation Angle. (FSW uses Fixed constatnts).

- Early Cycle 7: SPT file in raw “engineering” units - Later Cycle 7: SPT file in detector pixels in FSW coordinates - Cycle 11: _RAW, _CAL files in detector pixels (FSW)

SIAF[X, Y] = 256 - FSW[Y, X]

TA Images Can Be Used To Establish In-Band Magnitudes of Target for Acquisition Filter Used.

““Mode 2” Target Acquisition (TA)Mode 2” Target Acquisition (TA)PHOTOMETRIC ANCHOR (How Bright is My Target?)PHOTOMETRIC ANCHOR (How Bright is My Target?)

“Hole Locate” Lamp-Flat Background (2x7s ACCUM) Images May Be Used to Obtain H-Band Magnitude of Target.

Stellar PSF Cores Will Saturate at Shortest (0.2s) Exposure Times for: F160W: H < 7.2 F165M: H < 6.5 F171M: H < 5.5 F187N: H < 4.0 If H < 4 Need Mode-1 Target Acquisition

For subsequent Coronagraphic Imaging in Other Filters Take Unsaturated UNOCCULTED Images (when possible) to Establish PSF Core Photometry

BUT… TA Images are *NOT* Calibrated in OPUS Pipeline.

Shading Biases Target Centroids With Horizontal Field Gradients AND Photometry Through Flat-Field Errors

TA Process PROVIDES:

- Two F160W Lamp Flat Images & Backgrounds (used by on-board hole-location algorithm)

And… Necessary To Augment Reference Flats Used In Calibrating Follow-On Coronagraphic Imaging (But Not Used in OPUS Pipeline)

- Two Acquisition “ACCUM” Mode Images (for CR Minimization)

““Mode 2” Target Acquisition (TA)Mode 2” Target Acquisition (TA)ASTROMETRY / PHOTOMETRYASTROMETRY / PHOTOMETRY

Dark Current is (Generally) Not An Issue, Shading Is

TA Images may also be corrupted by “the bands”, which could be a problem if they go through the target

OPUS Does Not Currently Use Observed or “Synthetic” ACCUM Darks for TA Image Processing

Options: - Take “ACCUM” Mode Darks (+0.025s) - Build Source-Clipped Column-Medians from TA Images to Remove Shading Signature & DC Offsets Before Flat-Fielding

““Mode 2” Target Acquisition (TA)Mode 2” Target Acquisition (TA)ASTROMETRY / PHOTOMETRYASTROMETRY / PHOTOMETRY

EXAMPLE…..

A contemporaneousreference flat forthe region aroundthe coronagraphichole can (should)be made from the TA lamp flats &backgrounds (S/N~120, combined),And used to flat-field the subsequentcoronagraphic Images.

Note: 7s F160W Target Images in Background Frames

Coronagraphy with HST/NICMOSCoronagraphy with HST/NICMOS

SMOV3B Program Has Demonstrated Full Return of Capabilities

Coronagraphic Diffracted & Scattered Light Rejection Comparable to Cycle 7. Should be Fully Restored After Low Scatter-Point Mapping and Compensation.

Final Performance Metrics and Calibration Pending Completion of Cycle 11 Calibration Test Plan.

Ready to Resume NICMOS Coronagraphic Science (if any proposals are accepted for HST Cycle 12).

Coronagraphic Detectability (Direct and with PSF-Subtraction) Comparable to Cycle 7, with Increased Sensitivity Due to QE Improvement @ 77K (QE~37% in H-band relative to cycle 7).

SUMMARYSUMMARY

Glenn Schneider Glenn Schneider Steward Observatory, University of Arizona (NICMOS/IDT)Steward Observatory, University of Arizona (NICMOS/IDT)

Coronagraphy with HST/NICMOSCoronagraphy with HST/NICMOS**

*The *The NNear ear IInfrared nfrared CCamera & amera & MMulti-ulti-OObject bject SSpectrometerpectrometerExtending HST’s UV/Optical Panchromatic VisionExtending HST’s UV/Optical Panchromatic Vision

into the Near IR (0.8into the Near IR (0.8m —2.m —2.m)m)

http://nicmosis.as.arizona.edu:8000

[email protected]

General DescriptionGeneral Description““Coronagraphic Focus”Coronagraphic Focus”

• The f/24 (FDM) and f/45 (detector) image planes are suppose to be confocal. Because of the “dewar anomoly” they are not.

DIRECT DET

DIRECT FDA

CORON DETCORON FDA

200

400

600

800

1000

1200

0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5

RADIUS (ARCSECONDS)

COUNT

RATE/PIXEL

To achieve “Best Focus” at the detector (for “direct” imaging), a star image on the FDA mirror is de-focused, so light from the 1st Airy ring scatters off the edge of the coronagraphic hole with much greaterintensity (3x at 1.6m).


• The f/24 (FDM) and f/45 (detector) image planes are suppose to be confocal. Because of the “dewar anomoly” they are not.

DIRECT DET

DIRECT FDA

CORON DETCORON FDA

200

400

600

800

1000

1200

0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5

RADIUS (ARCSECONDS)

COUNT

RATE/PIXEL

To reduce edge scattering, and recover image contrast, the PAM mirror is moved (by ~ 2mm) for coronagraphic imaging.

As a result the unocculted PSF isslightly de-focused.

Question: Can you comment on the Coronagraphic Focus?

Answer: Follows…

F187N

F160W

F110W

Detector Intermediate Field Divider Mirror

SMOV/3B Coronagraphic Focus CheckSMOV/3B Coronagraphic Focus Check

Coronagraphic Focus Check - F187NAzimuthal Average Per Pixel Intensity

Focus @ FDA Mirror

Focus @ Detector

Coronagraphic Focus Check - F160WAzimuthal Average Per Pixel Intensity

Focus @ FDA Mirror

Focus @ Detector

Coronagraphic Focus Check - F110WAzimuthal Average Per Pixel Intensity

Focus @ FDA Mirror

Focus @ Detector

.

PSF CORE FWHM DIRECT CORON

1.934 pix 1.954 pix 0.1466” 0.1481”INTENSITYRADIUS (PIXELS)


The peak of an unocculted stellar PSF at the coronagraphic focus is reduced in intensity by ~ 17%.

This is more than an acceptable trade given the reduction by a factor of 3 in the scattered background near the coronagrahic hole.

DATA from SMOV/7157(Cycle 7) and SMOV/8984 (Cycle 11).

glenn schneider steward observatory, university of arizona (nicmos/idt) coronagraphy with hst/nicmos...

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