Calibration Status and Results for Wide Field Camera
Calibration Status and Results for Wide Field Camera 3 Randy A. Kimble (GSFC) and the WFC 3 Team HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 1
Outline • Purpose/potential of WFC 3 • 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, randy. a. kimble@nasa. gov 2
Key Team Members Supporting Calibration Science IPT (STSc. I) J. Mac. Kenty GSFC Detector Characterization Laboratory S. Baggett B. Hill (also Science IPT) T. Brown G. Delo H. Bushouse R. Foltz D. Figer E. Malumuth G. Hartig A. M. Russell B. Hilbert A. Waczynski N. Reid Y. Wen M. Robberto • WFC 3 also supported by Science Oversight Committee, chaired by Bob O’Connell/University of Virginia HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 3
Origins/Purpose of WFC 3 • WFC 3 originated when HST’s nominal observing lifetime was first extended from 2005 to 2010: develop a new camera for installation during Servicing Mission 4, to extend and enhance HST’s imaging capability • If SM 4 approved, era of WFC 3 operation now likely to be late 2007/2008 2013 and perhaps beyond • WFC 3 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 HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 4
Key Aspects of WFC 3 • Uniquely capable in the near-UV – 200 to 400 nm • Uniquely capable in the near-IR – without cryogen or mechanical cryocooler! – 800 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, randy. a. kimble@nasa. gov 5
WFC 3’s Intended Destination WFC 3 is intended to replace the extraordinarily successful but aging WFPC 2 in its radial instrument bay. HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 6
Overall WFC 3 Configuration B-Latch Dimensions: 7. 5’ x 7’ x 3’ HST Cal Conf -- Oct 27, 2005 Weight: 907 lbs Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 7
WFC 3 Interior Configuration HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 8
UVIS Channel Summary Key Properties • 200 – 1000 nm • 4 K x 4 K CCD mosaic (two 2 K x 4 K UV-optimized CCDs) • 0. 04” x 0. 04” pixels, 160” x 160” field of view The WFC 3 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, randy. a. kimble@nasa. gov 9
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). HST Cal Conf -- Oct 27, 2005 NUV Observations Probe Age of Stellar Populations Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 10
CCD Detectors • The WFC 3 CCDs, developed by Marconi (now e 2 v) 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, randy. a. kimble@nasa. gov 11
IR Channel Summary Key Properties • 800 – 1700 nm • 1 K x 1 K Hg. Cd. Te 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 WFC 3 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 HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 12
IR Channel Science Goals The IR channel will take advantage of the dark IR sky in space to study: IR Color-Color Identification of High-z Galaxies • 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. HST Cal Conf -- Oct 27, 2005 Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, randy. a. kimble@nasa. gov 13
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 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, randy. a. kimble@nasa. gov 14
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 WFC 3’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, randy. a. kimble@nasa. gov 15
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, randy. a. kimble@nasa. gov 16
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