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Calibration Status and Results for Wide Field Camera 3 Randy A. - - PowerPoint PPT Presentation

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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, randy.a.kimble@nasa.gov Outline

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Calibration Status and Results for Wide Field Camera 3

Randy A. Kimble (GSFC) and the WFC3 Team

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Outline

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

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. Baggett
  • B. Hill (also Science IPT)
  • R. Boucarut
  • T. Brown
  • G. Delo
  • P. Arsenovic
  • H. Bushouse
  • R. Foltz
  • J. Kim Quijano
  • D. Figer
  • E. Malumuth
  • M. Quijada
  • G. Hartig
  • A. M. Russell
  • R. Telfer
  • B. Hilbert
  • A. Waczynski
  • N. Reid
  • Y. Wen
  • M. Robberto
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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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 – 200-1000 nm in UVIS channel; 850-1700 nm in IR channel – complementary to ACS

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

WFC3’s Intended Destination

WFC3 is intended to replace the extraordinarily successful but aging WFPC2 in its radial instrument bay.

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Overall WFC3 Configuration

Dimensions: 7.5’ x 7’ x 3’ Weight: 907 lbs

B-Latch

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

WFC3 Interior Configuration

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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
  • f galaxies
  • Ly α 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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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.

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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 10-20+ 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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

IR Channel Science Goals

The IR channel will take advantage

  • f 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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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.

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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 – 1st opportunity for end-to-end look at IR channel – Not a full science calibration, but all critical performance issues examined

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Flight Subsystems Integrated for End-to-End Testing in 2004

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Thermal/Vac Test Setup

Optical Stimulus RIAF WFC3 Cryopanels

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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

– http://www.stsci.edu/hst/wfc3/documents/ISRs – Easy to find: STScI → HST → Instruments → WFC3 → ISRs

  • Results confirm the powerful performance of WFC3 across its

wide spectral range

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

UVIS Results

Characteristic CEI spec; goal Measured Dark current <20 e/pix/hour 0.2-0.4 e/pix/hour Read noise (rms) <4 e/pix; <3 e/pix 2.98-3.08 e/pix Linearity <5% deviation over 100-50,000 e <3% deviation Full-well >50,000 e/pix; >85,000 e/pix ~68,000 e/pix Encircled energy 250nm: >0.75; >0.80 in 0.20” 633nm: >0.75; >0.80 in 0.25” 250nm: 0.78-0.81* 633nm: 0.77-0.81* Cal System 10,000 e/pix in <10 min <1 min Uniform to <2x ~7x Filter ghosts <0.2% of incident in a ghost Up to ~15% Image stability <10 milli-arcseconds over 2 orbits 15-50 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).

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

UVIS Channel Shows Excellent End-to-End Image Quality

810nm 250nm 350nm 633nm 810nm

Goals Specs

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

UVIS System Throughput

UVIS throughput very close to or better than predictions

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

IR Results

Characteristic CEI spec; goal Measured 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 energy 1000nm: >0.56; >0.61 in 0.25” 0.52-0.56* >0.72; >0.80 in 0.37” 0.73-0.77* 1600nm: >0.48; >0.54 in 0.25” 0.40-0.44* >0.75; >0.80 in 0.60” 0.77-0.81* Filter ghosts <0.2% of incident in a ghost <0.2% Cal System 10,000 e/pix in <10 min <1 min Uniform to <2x ~25x Image stability <20 milli-arcseconds over 2 orbits 15-50 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).

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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.

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

WFC3 IR Throughput

IR throughput 10-15% below component predictions; this discrepancy is a bit beyond the expected error bars.

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

New UV Filters Improve Ghost Performance and Increase Sensitivity

0.1 0.2 0.3 0.4 0.5 0.6 190 210 230 250 270 290 310 330 350 370 390 410 430 wavelength(nm) transmission f218w - new f225w - new f275w - new f300x - new

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Point-Like Filter Ghosts (e.g. F606W)

F606W replacement – nearly ghost-free

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Improved F606W and Stromgren Filters Ready for Installation

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 390 415 440 465 490 515 540 565 590 615 640 665 690 715 wavelength (nm) transmission f606w - new f606w - orig f410m - new f410m - orig f467m - new f467m - orig f621m - new f621m - orig 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 390 415 440 465 490 515 540 565 590 615 640 665 690 715 wavelength (nm) transmission f606w - new f606w - orig f410m - new f410m - orig f467m - new f467m - orig f621m - new f621m - orig

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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.
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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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 On Substrate Off

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Dramatic QE Improvement with Substrate Removal

10 20 30 40 50 60 70 80 90 100 200 600 1000 1400 1800 Wavelength (nm) QE (%)

FPA 64 FPA 102 FPA 104 FPA 105 FPA 106 FPA 114

QE For Devices With High and Flat QE

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Dramatic QE Improvement with Substrate Removal (2)

10 20 30 40 50 60 70 80 90 100 200 600 1000 1400 1800 Wavelength (nm) QE (%)

FPA 64 FPA 107 FPA 110 FPA 112 FPA 113 FPA 115

QE For Devices With Sloped QE

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Cumulative Dark Distributions

T=150K

Dark Current For Devices With High and Flat QE

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Cumulative Dark Distributions

Dark Current For Devices With Sloped QE T=150K

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

FPA114 Cumulative Dark vs. Temperature

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Survey Speed Metric (Speed x FOV) for Candidate IR Detectors

Detector CDS noise Mean dark at 145K F110W F160W F126N FPA64 24 0.04 (100%) 12.5 9.1 11.7 FPA112 24 0.09 (100%) 15.6 7.7 12.4 FPA104 33 0.14 (90%) 28.7 10.4 18.2 FPA105 28 0.10 (90%) 26.6 10.0 20.6 Potential FPA 20 0.04 (100%) Flat 90% QE 31.4 12.5 36.1

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

Discovery Efficiency with Improved Filters and IR Detector

Curves connect values at central wavelengths of available broadband filters – instruments’ spectral coverage is wider

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HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy.a.kimble@nasa.gov

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