1. Glenn Schneider Steward Observatory, University of Arizona (NICMOS/IDT) Coronagraphy with HST/NICMOS * *The Near Infrared Camera & Multi-Object Spectrometer Extending HST’s UV/Optical Panchromatic Vision into the Near IR (0.8  m —2.  m) http://nicmosis.as.arizona.edu:8000 gschneider@as.arizona.edu Hubble Space Telescope Third Calibration Workshop 18 October 2002 Baltimore, Maryland

2. Diffraction Limited Imaging in Optical/Near-IR > 98% Strehl Ratios @ all  s 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’s Unique Venue for High Contrast Imaging Unique Venue for High Contrast Imaging Background Rejection* 1.6  m: ~10 -6 pix -1 @ 1” 1.1  m: ~10 -5 in 2”-3” annulus *w.r.t. central pixel *w.r.t. central pixel F central (H) = 11% F star F central (H) = 11% F star Highly Accurate Pointing Repeatability & Control

3. Scientific Areas of Investigation Enabled With Today’s Capabilities on HST via PSF-Subtracted Coronagraphic Imaging Damped L  Absorbers LBQS 1210+1713 Young Extra-Solar Planet* & Brown Dwarf Companions * < few x 10 6 yr at 1” TWA 6 Circumstellar Disks f disk /f * > few x 10 -4 at 1”  0.1” 1" HR 4796A

4. .. 0 6 7 8 9 10 Log 10 Age (years) 80M jup 14M jup JUPITER SATURN STARS (Hydrogen burning) BROWN DWARFS (Deuterium burning) PLANETS 200M jup Evolution of M Dwarf Stars, Brown Dwarfs and Giant Planets (from Adam Burrows) -10 -8 -6 -4 -2 Cooling Curves for Substellar Objects

5. 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) 6 4 Planet-Building Timeline Disk Evolution/Dissipation(?)

6. Coronagraphic Companion Detection PSF “Roll Subtraction” HD 102982 H = 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

7. 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 3003 H = 9.3 TA Persistence Ghost Images

8. BACKGROUNDREDUCTIONBACKGROUNDREDUCTION Coronagraphic Performance (G2V) w.r.t. central pixel w.r.t. central pixel F central (H) = 11% F star F central (H) = 11% F star

9. General Description Coronagraphic 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

10. Two Integrations from Median of 3 Multiaccums Each Total 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 Coronagraphic Companion Detection PSF “Roll Subtraction” EXAMPLE: TWA 6, H = 6.9

11. Linear Display 0—2 ADU/sec/pixel; 2.19E-6 Janskys/ADU/sec/pixel Coronagraphic Companion Detection Unresolved (Point-Like) Object: H =20.1,  H = 13.2,  =2.5”

12. Linear Display -0.4 — +0.4 ADU/sec/pixel; 2.19E-6 Janskys/ADU/sec/pixel Coronagraphic Companion Detection PSF “Roll Subtraction” 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).

13. Linear Display -0.4 — +0.4 ADU/sec/pixel; 2.19E-6 Janskys/ADU/sec/pixel Coronagraphic Companion Detection PSF “Roll Subtraction” Each independent point- source image is S/N ~ 20 Geometrical Rectification And De-Spiking* * NICMOS/IDT Post-Processing & Analysis S/W: DSKP & IDP3 ftp://nicmos.as.arizona.edu/

14. Coronagraphic Companion Detection PSF “Roll Subtraction” A spatial filter is applied to the combined image to further reject image artifacts with characteristic frequencies not commensurate with the size of a stellar PSF. 0.01.02.01.02.0 Arc Seconds PSF FWHM = 0.16" NICMOS F160W 25 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 TWA6

15. 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} TWA6 and Median of 50 G-K Stars in NICMOS Survey * Determined by Noise Statistics AND Model Star Implantation

16. PRELIMINARY Post SM-3B Coronagraphic Performance Characterization 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

17. 0 — +2.0 ADU/sec/pixel 2.19E-6 Jy/ADU/sec/pixel Coronagraphic First Light Post-SM3B “Out of the Box” CYCLE 7 GTO/7227 CYCLE 11 SMOV3B/8983 0 — +2.75 ADU/sec/pixel 1.59E-6 Jy/ADU/sec/pixel

18. -0.4 — +0.4 ADU/sec/pixel 2.19E-6 Jy/ADU/sec/pixel -0.55 — +0.55 ADU/sec/pixel 1.59E-6 Jy/ADU/sec/pixel CYCLE 7 GTO/7227 CYCLE 11 SMOV3B/8983 Coronagraphic First Light Post-SM3B “Out of the Box”

19. Coronagraphic Performance (M9.5V+) Direct Coronagraphic F160WF160W

20. Coronagraphic PSF-Subtraction Induced Image Artifacts The Dominant Source of Systematic Error (“Noise”) * Imperfections in PSF-subtractions result in residuals larger than expected 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

21. “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.

22. Coronagraphic “Hole” On Camera 2 Field Divider Mirror @ OTA f/24 Focus Physical Radius: 170  m 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 Description

23. F160W PSF “Mapped” Onto Coronagraphic Hole A small change in energy distribution in the first Airy ring (due to breating induced focus shifts) cause scattering sites on the hole-edge to “light up” and change, significantly, the downstream scattering.

27. A Few Words on Circumstellar Disks… Direct Image HH30 Obscured Observing young circumstellar disks With obscured central stars is not difficult. Disk systems with unembedded, or only marginally obscured central stars are much more observationally challenging and require PSF-subtracted coronagraphy. GM AUR Unembedded (A v < 0.5) Coronagraph + PSF Subtraction J * = 0.33 Jy H * = 0.40 Jy Red Polar Lobes 10  Jy arcsec -2 Lower Scattering Surface 0.2 mJy arcsec -2 Faint Blue Ribbon

28. 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 4796A

29. 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 141569A

30. Calibrating Coronagraphic Data Be Critical of “Pipeline” Results Performance Levels Discussed ASSUME Properly Calibrated Data Local and Global Deviations from True Photometric Backgrounds 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

31.  REFERENCE FLATS: - Hole “imprint” in CDBS flats is static, in reality it moves. Augment Reference Flats with Contemporaneous TA Lamp Flats. Calibrating Coronagraphic Data Be Critical of “Pipeline” Results  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

32. OTFR/CALNIC 10 October 2002 Using “Best” Ref Data CALNICA ANALOG (+ Bad Pixel Replacement) ObsDARKS/LinFLATS Calibrating Coronagraphic Data Be Critical of “Pipeline” Results Flat-Field Imprint Non-Zero Background Quadrant Offsets “Photometrically Challenged” Column Dead, 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

33. Calibrating Coronagraphic Data Be Critical of “Pipeline” Results 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

34. OTFR/CALNIC 10 October 2002 Using “Best” Ref Data CALNICA ANALOG (+ Bad Pixel Replacement) ObsDARKS/LinFLATS Post-Processing to Remove Electronic Image Artifacts: Saturation Bands & Echos Calibrating Coronagraphic Data Be Critical of “Pipeline” Results

35. “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)

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

37.  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) 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]

38.  TA Images Can Be Used To Establish In-Band Magnitudes of Target for Acquisition Filter Used. “Mode 2” Target Acquisition (TA) 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

39.  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) ASTROMETRY / PHOTOMETRY

40.  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) ASTROMETRY / PHOTOMETRY EXAMPLE…..

42. A contemporaneous reference flat for the region around the coronagraphic hole can (should) be made from the TA lamp flats & backgrounds (S/N ~120, combined), And used to flat- field the subsequent coronagraphic Images. Note: 7s F160W Target Images in Background Frames

43. Coronagraphy 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). SUMMARY

44. Glenn Schneider Steward Observatory, University of Arizona (NICMOS/IDT) Coronagraphy with HST/NICMOS * *The Near Infrared Camera & Multi-Object Spectrometer Extending HST’s UV/Optical Panchromatic Vision into the Near IR (0.8  m —2.  m) http://nicmosis.as.arizona.edu:8000 gschneider@as.arizona.edu

45. General Description “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. 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 greater intensity (3x at 1.6  m).

46. General Description “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. To reduce edge scattering, and recover image contrast, the PAM mirror is moved (by ~ 2mm) for coronagraphic imaging. As a result the unocculted PSF is slightly de-focused.

47. Question: Can you comment on the Coronagraphic Focus? Answer: Follows…

48. F187N F160W F110W Detector Intermediate Field Divider Mirror SMOV/3B Coronagraphic Focus Check

49. Coronagraphic Focus Check - F187N Azimuthal Average Per Pixel Intensity Focus @ FDA Mirror Focus @ Detector

50. Coronagraphic Focus Check - F160W Azimuthal Average Per Pixel Intensity Focus @ FDA Mirror Focus @ Detector

51. Coronagraphic Focus Check - F110W Azimuthal Average Per Pixel Intensity Focus @ FDA Mirror Focus @ Detector

52. PSF CORE FWHM DIRECT CORON 1.934 pix 1.954 pix 0.1466” 0.1481” General Description “Coronagraphic Focus” 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).