HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Calibration Status and Results for Wide Field Camera 3 Randy A. Kimble (GSFC) and the WFC3 Team

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Outline Purpose/potential of WFC3 Configuration of instrument Ambient and thermal-vac calibration results Improvements in work – filters, crosstalk, IR detector Future calibration plans

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Key Team Members Supporting Calibration WFC3 also supported by Science Oversight Committee, chaired by Bob O’Connell/University of Virginia Science IPT (STScI) J. MacKenty Detector Characterization Laboratory (GSFC) Filter Evaluation S. BaggettB. Hill (also Science IPT)R. Boucarut T. BrownG. DeloP. Arsenovic H. BushouseR. FoltzJ. Kim Quijano D. FigerE. MalumuthM. Quijada G. HartigA. M. RussellR. Telfer B. HilbertA. Waczynski N. ReidY. Wen M. Robberto

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Origins/Purpose of WFC3 WFC3 originated when HST’s nominal observing lifetime was first extended from 2005 to 2010: facility instrument conceived for installation during Servicing Mission 4, to extend and enhance HST’s imaging capability If SM4 approved, era of WFC3 operation now likely to be late 2007/2008  2013 and beyond? WFC3 has been designed as a powerful general purpose camera: –widest spectral coverage of any HST instrument – nm in UVIS channel; nm in IR channel –complementary to ACS

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Key Aspects of WFC3 Unique capabilities in the near-UV –200 to 400 nm Unique capabilities in the near-IR – without cryogen or mechanical cryocooler! –850 to 1700 nm (though warm, HST is very powerful in this range) Large and diverse set of filters and grisms: 63 UVIS, 16 IR Very capable accompaniment to ACS in the red, with more filters, fresh start with respect to radiation damage, and greater tolerance of CTE degradation

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, WFC3’s Intended Destination WFC3 is intended to replace the extraordinarily successful but aging WFPC2 in its radial instrument bay.

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Overall WFC3 Configuration Dimensions: 7.5’ x 7’ x 3’Weight: 907 lbs B-Latch

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, WFC3 Interior Configuration

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, UVIS Channel Summary Key Properties 200 – 1000 nm 4K x 4K CCD mosaic (two 2K x 4K UV-optimized CCDs) 0.04” x 0.04” pixels, 160” x 160” field of view The WFC3 UVIS channel will extend high-sensitivity, large-format imaging at HST’s sharp angular resolution to the near UV. Relative fields of view of HST’s NUV imagers

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, UVIS Channel Science Goals The UVIS channel will be particularly well suited to the study of: Star formation history of galaxies (see figure at right) Chemical enrichment history of galaxies Ly  dropouts at z = 1 – 2. It will also probe one of the darkest spectral regions of the natural sky background (~200 nm). NUV Observations Probe Age of Stellar Populations

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, CCD Detectors The WFC3 CCDs, developed by Marconi (now e2v) are shown in their flight housing (left) and mounted in the instrument (right). The end-to-end read noise for the flight CCDs and electronics is 3 e- rms for all four readout amplifiers.

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, IR Channel Summary Key Properties 850 – 1700 nm 1K x 1K HgCdTe array with 1.7 micron cutoff 0.13” x 0.13” pixels, 139” x 123” field of view zodiacal-background-limited sensitivity in broadband filters The WFC3 IR channel will provide a x increase in survey speed vs. NICMOS + cryocooler, with finer angular resolution and improved stability, photometric accuracy, and cosmetics. Relative fields of view of HST’s IR imagers

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, IR Channel Science Goals The IR channel will take advantage of the dark IR sky in space to study: Type Ia supernovae and the accelerating universe High-redshift galaxy formation (high-z dropouts) – note the strong NIR color-color discrimination of high-z galaxies in the figure at right Sources of cosmic re-ionization Dust-enshrouded star formation Water and ices in the solar system. IR Color-Color Identification of High-z Galaxies

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, IR Detectors The novel 1.7 micron cutoff wavelength of the IR array (left), developed by Rockwell Scientific, permits low-dark-current operation at a temperature of <150 K, achievable with thermo-electric cooling alone. A cooled inner shield (center) within the detector housing (right) helps to minimize the thermal background radiation incident on the array.

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Ambient and Thermal-Vac Calibrations Performed During “cancellation period” of 2004, instrument was fully integrated in a “non-final” mode, in which a number of hardware issues were tagged as “liens”, but not closed out We targetted a “performance characterization” in which WFC3’s performance could be demonstrated for the purposes of contemplating non-HST use Extensive suite of tests and calibrations performed, both in ambient and thermal-vac conditions –Ambient tests of UVIS channel –Thermal-vac tests of both channels – 1 st opportunity for end-to-end look at IR channel –Not a full science calibration, but all critical performance issues examined

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Flight Subsystems Integrated for End-to-End Testing in 2004

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Thermal/Vac Test Setup Optical Stimulus RIAF WFC3 Cryopanels

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Thermal/Vac Performance Highlights Overall instrument performed very well – never came up to air for an instrument issue 13,000 images obtained, assessing all aspects of WFC3 performance Detailed results documented in several dozen Instrument Science Reports – –Easy to find: STScI → HST → Instruments → WFC3 → ISRs Results confirm the powerful performance of WFC3 across its wide spectral range

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, UVIS Results CharacteristicCEI spec; goalMeasured Dark current<20 e/pix/hour e/pix/hour Read noise (rms)<4 e/pix; <3 e/pix e/pix Linearity<5% deviation over ,000 e<3% deviation Full-well>50,000 e/pix; >85,000 e/pix~68,000 e/pix Encircled energy250nm: >0.75; >0.80 in 0.20” 633nm: >0.75; >0.80 in 0.25” 250nm: * 633nm: * Cal System10,000 e/pix in <10 min<1 min Uniform to <2x~7x Filter ghosts<0.2% of incident in a ghostUp to ~15% Image stability<10 milli-arcseconds over 2 orbits15-50 mas * Specs apply to performance with OTA. Measurements obtained with CASTLE require corrections for differences in the optical systems. 250nm EE likely to fall just below CEI requirement (~0.72).

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, UVIS Channel Shows Excellent End-to-End Image Quality 810nm 250nm 350nm 633nm 810nm Goals Specs

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, UVIS System Throughput UVIS throughput very close to or better than predictions

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, IR Results CharacteristicCEI spec; goalMeasured Dark current<0.4 e/pix/sec; <0.1 e/pix/sec~0.1 e/pix/sec Read noise (rms)<15 e/pix; <10 e/pix (CDS pair)~23 e/pix Full-well>100,000 e/pix; >150,000 e/pix~100,000 e/pix Encircled energy1000nm: >0.56; >0.61 in 0.25” * >0.72; >0.80 in 0.37” * 1600nm: >0.48; >0.54 in 0.25” * >0.75; >0.80 in 0.60” * Filter ghosts<0.2% of incident in a ghost<0.2% Cal System10,000 e/pix in <10 min<1 min Uniform to <2x~25x Image stability<20 milli-arcseconds over 2 orbits15-50 mas * Corrections for OTA vs. CASTLE likely to cause 1.0μm core EE to meet CEI spec (~0.60), while 1.6μm core EE likely to fall just below spec (~0.46).

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, IR Channel Shows Excellent End-to-End Image Quality Thermal/vac was first opportunity to see IR channel operate end- to-end. Very gratifying to see how well it worked overall. Below: Image, encircled energy vs. radius at 1 micron wavelength.

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, WFC3 IR Throughput IR throughput 10-15% below component predictions; this discrepancy is a bit beyond the expected error bars.

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Discovery Efficiency (Throughput x FOV) Based on Thermal-Vac Results Curves connect values at central wavelengths of available broadband filters – instruments’ spectral coverage is wider

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, UVIS Filter Ghosts Nasty ghost images in a small subset of UVIS filters Inter-reflections between “air- gap” substrates or coating layers Excellent replacements in hand for all severe cases; two less critical shipping this week Strong field-dependent ghosts in current F225W New F225W

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, New UV Filters Improve Ghost Performance and Increase Sensitivity

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Point-Like Filter Ghosts (e.g. F606W) F606W replacement – nearly ghost-free

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Improved F606W and Stromgren Filters Ready for Installation

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, UVIS Crosstalk Solution In Hand Electronic crosstalk observed from quadrant to quadrant of 4-amp readout Analogous to ACS “extended source” crosstalk, but stronger (5-10e) Source traced to A/D conversion of pixel n while sampling pixel n+1 Eliminate by speeding up A/D conversion and fitting it into pixel period away from sampling (<0.1e remains) Validated on non-flight elect.

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, IR FPA Radiation Effect WFC3 radiation testing revealed a radiation-induced background effect in the IR focal plane arrays Diffuse background produced, in addition to localized “hits” Followup testing in May 2004 identified the source as luminescence in the thick CdZnTe substrate on which the HgCdTe detectors are grown Radiation- induced background morphology 800 nm flat-field morphology

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Estimating On-Orbit Impact Extrapolation to flight situation is very difficult without full understanding of the microphysics of the phenomenon But making our best estimate, we predict ~0.25 electrons/pixel/second in orbit from the radiation effect Significant compared with other backgrounds, potentially leading to significant impact on IR channel sensitivity Estimate is very uncertain, but not a risk we want to take Fortunately, solution exists: substrate-removed detectors are now available! Fabrication of new IR arrays for WFC3 is underway

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Insignificant Background Seen In Substrate-Removed Detector The diffuse radiation-induced background is reduced to undetectable levels when the substrate is removed Scales to negligible background for the on-orbit case Substrate OnSubstrate Off

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Dramatic QE Improvement with Substrate Removal QE For Devices With High and Flat QE

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Dramatic QE Improvement with Substrate Removal (2) QE For Devices With Sloped QE

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Cumulative Dark Distributions T=150K Dark Current For Devices With High and Flat QE

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Cumulative Dark Distributions Dark Current For Devices With Sloped QE T=150K

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, FPA114 Cumulative Dark vs. Temperature

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Survey Speed Metric (Speed x FOV) for Candidate IR Detectors Detector CDS noise Mean dark at 145K F110WF160WF126N FPA (100%) FPA (100%) FPA (90%) FPA (90%) Potential FPA (100%) Flat 90% QE

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Discovery Efficiency with Improved Filters and IR Detector Curves connect values at central wavelengths of available broadband filters – instruments’ spectral coverage is wider

HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, WFC3 SM4 Flow Shuttle Launch 4/21-6/15/05 5/25/06– 12/1/06 Pre-IR Detector Instrument Level Testing (Includes T/V test #1) Delivery to HST I&T 3/15/07 Pre Component Removal Activities 4/26– 11/03/05 Optical Filter Fab and Test Build Flight IR1 Detector Assy 2/15/05 – 11/15/06 7/25/05 - 3/22/06 SOFA Rework at GSFC/Moog/Ball Fab and test new IR FPA 4/26 – 2/7/06 Component Removal (SOFA, GCHP, Cal Source, IR Grism LVPS boards, DEB board, SOFA Relay Box) 6/16-7/22/05 IR Grism Rework 6/17 – 11/25/05 7/25 – 11/23/05 Electrical Mod/ Fix Change out Lamps on Cal Source & Test 9/9-11/15/05 Heat Pipe Fab and Test 4/25/05 -5/5/06 Instrument Level Testing (EMI/EMC & T/V test #2) 12/29/06– 3/14/07 12/2/06 – 12/28/06 Flight IR 1 installation and final instrument closeout 10/5/05 – 5/24/06 Component Reassembly