HST Cal Conf -- Oct 27, 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, 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, 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 GSFC Detector Characterization Laboratory S. BaggettB. Hill (also Science IPT) T. BrownG. Delo H. BushouseR. Foltz D. FigerE. Malumuth G. HartigA. M. Russell B. HilbertA. Waczynski N. ReidY. Wen M. Robberto

HST Cal Conf -- Oct 27, 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: develop a new camera 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 perhaps 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, Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Key Aspects of WFC3 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, 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, 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, Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, WFC3 Interior Configuration

HST Cal Conf -- Oct 27, 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, 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, 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, Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, IR Channel Summary Key Properties 800 – 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 10-20x 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, 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, 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, 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, Calibration Status and Results for Wide Field Camera 3 – R. Kimble/GSFC, Flight Subsystems Integrated for End-to-End Testing in 2004