Ken Sembach 27-October-2005

1. ACS Calibration Status Ken Sembach 27-October-2005 ACS Website http://www.stsci.edu/hst/acs

2. ACS Calibration Teams at STScI and ST-ECF John Biretta Ralph Bohlin Marco Chiaberge Mauro Giavalisco Shireen Gonzaga Colin Cox Linda Dressel Andy Fruchter Ron Gilliland Vera Kozhurina-Platais Jesús Maíz-Apellániz Ray Lucas Jennifer Mack Max Mutchler Cheryl Pavlovsky Charles Proffitt Adam Riess Kailash Sahu Ken Sembach Marco Sirianni Nolan Walborn ST-ECF Richard Hook Martin Kümmel Sören Larsen Jeremy Walsh • This talk is an overview of ACS calibration activities. • See the many talks/posters here for more details. • People listed below are good sources of information.

3. ACS Status / Operation • All modes continue to operate well • Two-gyro performance nominal • Calibration plan for Cycle 14 • STScI team has reviewed plans from previous cycles • Continuing calibrations for most previous programs (ongoing usual calibration activities) • New programs to bring SBC calibrations up to the standard of HRC/WFC calibrations, to better characterize the ramp filters, ultraviolet narrow-band red leak, and to estimate T-dependence of QE, CTE, and hot pixel growth • ACS usage charted on STScI metrics page • Provides information about most frequently used modes • http://www.stsci.edu/hst/metrics/SiUsage

4. Cycle 14 - Routine Monitoring Programs

5. Cycle 14 - Special Calibration Programs

6. Cycle 13 - Special Calibration Programs

7. Cycle 14 - Calibration Orbit Summary * Two programs (PI = Dolphin): ACS zero point verification / Faint standard calibration

8. SBC flatfield Recent ACS ISRs • Grism wavelength calibration • ISR 2005-08 (Larsen & Walsh) • CCD internal flat fields • ISR 2005-09 (Bohlin & Mack) • SBC pixel-pixel flat field • ISR 2005-04 (Bohlin & Mack) • Astrometric improvements • ISR 2005-06 (Koekemoer et al.) • HRC polarimetry • ISR 2005-10 (Kozhurina-Platais & Biretta) • Two-gyro calibrations • I. Pointing Stability (ISR 2005-07; Koekemoer et al.) • II. Coronagraphic Performance (ISR 2005-05; Cox & Biretta) Complete list of ISRs at http://www.stsci.edu/hst/acs/documents/isrs

9. ACS High Resolution Channel • Typically accounts for ~15-20% of ACS observing time • Two-gyro checkout • PSF shape / stability • See poster by Pavlovsky • Updated internal flat fields • ISR 2005-09; Bohlin & Mack • See talk by Mack • Flats for use with polarizer filters • ISR 2005-10; Kozhurina-Platais & Biretta • PSFs and distortion corrections • ISR 2004-15; Anderson & King (NASA, ESA, and J. Garvin (NASA/GSFC)

10. ACS Instrument Performance in Two-Gyro Mode is Excellent 186 ACS/HRC exposures Min (FWHM) = 1.89 Avg (FWHM) = 2.00 Max (FWHM) = 2.19 PSF analayses by M. Sirianni, C. Pavlovsky, R. Lucas Three-gyro historical data Avg (FWHM) = 2.04±0.03 August 2005 114 exposures 3 clusters - NGC 2298 - NGC 1891 - NGC 6752 October 2005 72 exposures 1 cluster (CVZ) - NGC 6752

11. ACS Wide Field Channel • Typically accounts for ~75-80% of ACS observing time • Updated internal flat fields • ISR 2005-09; Bohlin & Mack • Astrometric accuracy using GSC2 • See poster by Koekemoer, also ISR 2005-06 • Photometric stability • ISR 2004-17; Riess • See also talk by Mack • PSFs and distortion corrections • See talk by Anderson NASA, ESA and The Hubble Heritage Team (STScI/AURA)

12. SBC flatfield ACS Solar Blind Channel • Typically accounts for ~3% of ACS observing time • More attention w/ loss of STIS • New pixel-pixel flat field available • ISR 2005-04; Bohlin & Mack • Updated darks available • ISR 2004-14; Cox • New calibrations planned • Geometric distortion correction (see poster by Maíz-Apellániz) • Prism wavelength calibration • See SBC overview poster by Cox et al.

13. HD 130948A 3-gyro F625W HD 130948A 2-gyro F625W HD 216149 2-gyro F625W ACS Coronagraphy 3.0” spot • Typically ~3-4% of ACS observing time • Coronagraphic flat fields • ISR 2004-16; Krist • Two-gyro coronagraphy performance • ISR 2005-05; Cox & Biretta 1.8” spot

14. ACS Grism/Prism Spectroscopy • In Cycle 14 • ~25% of HRC observing time • ~9% of WFC observing time • ~23% of SBC observing time • Slitless spectroscopy with ACS • Talks by Kümmel, Meurer, and Maíz-Apellániz • Grism spectroscopy • WFC/G800L wavelength calibration (ISR 2005-08; Larsen & Walsh) • WFC and HRC G800L flat field and sensitivity (ISR 2005-02; Walsh & Pirzkal) • Prism spectroscopy • Prisms used more since shutdown of STIS • New wavelength/flux calibrations (see poster by Larsen) • Software improvements • aXe spectral extraction of prism/grism data (see poster by Walsh)

15. QE & CTE Temperature Dependence • 12 orbit study to determine T-dependence of CTE, QE, hot pixel growth, etc., has relevance for • Performance of ACS in the coming years (T may increase) • Future CTE temperature/time dependent corrections • Aft-Shroud Cooling System considerations for SM4 • Test scheduled for November (47 Tuc, GOODS-N) fields) will obtain data at the current operating temperature and colder/hotter temperatures • WFC: -81˚, -77˚ (current), and -74˚ C • HRC: -86˚, -80˚ (current), and -76˚ C

16. Serial Readout B A Parallel readout Charge Transfer Efficiency Degradation of the Charge Transfer Efficiency (CTE) is a well known problem for space-operated CCDs. Even if only a very small part of the charge packet is left behind in each pixel-to-pixel transfer the effect is severe: CTE=99.99 % after 2048 transfers results in loss of ~19% of the signal Current parallel CTE (@1620 e-) is 99.997% Effects of poor CTE: - Signal is lost during the readout Lower S/N Degraded detection limit - Some trapped charge is released on short time scales, creating tails Increased noise PSF alteration - CTE depends on the signal level, position, background, and time Low number of transfers High number of transfers

17. WFC Parallel CTE Variation with Time

18. years % WFC ACS CCD Hot Pixel Growth Hot pixels continue to increase because of radiation damage to the CCDs. Effects of hot pixels can be reduced by dithering exposures. Monthly anneals heal most of the hot pixels (see poster by Marco Sirianni).

19. ACS Pipeline Calibrations (see talk by Max Mutchler) WFC Bias • Most recent ACS pipeline improvements • Emphasis on bias and dark calibrations, including hot pixels • Reference file production and delivery • Data quality flagging and monitoring • Ramifications for downstream data reductions, e.g. drizzling WFC Dark

20. Automated ACS Bias and Dark Reference File Production, and Improved Detector Trend Analysis Ray A. Lucas (STScI), Mike Swam (STScI), Max Mutchler (STScI), and Marco Siriarnni (ESA/STScI) Users Automatic Copy of Daily Darks and Statistics to Storage Disk for Long- Term Trend Analysis Files Delivered to OPUS and Archive For Use in Pipeline and OTFC Automated Retrieval of Raw Data From STScI Data Archive Automated Processing to Make Reference Biases and Darks from Raw Data Automatic Triggering Based on HST Schedule

21. ACS Documentation • Cycle 15 Instrument Handbook streamlining and updates • Length reduced by ~15% (310 pages trimmed to 262) w/o loss of content • Some calibration plan reference material moved to ACS website • Indexing update to make information easier to access in both paper and electronic versions of handbook • Released with Cycle 15 Call for Proposals • Cycle 15 Data Handbook update planned • Minor updates to wording in various places and syntax in examples

22. Hubble Makes Movie of Neptune's Dynamic Atmosphere Scattered Light from the Boomerang Nebula Hubble/Chandra Image SNR N132D in the LMC Hubble Pinpoints Doomed Supernova Progenitor Comet 9P/Tempel 1 Before and After Deep Impact Hubble Spies a Zoo of Galaxies Black Hole in Search of a Home "Big Baby" Galaxies in the Newborn Universe Hubble Tracks Ceres Debris Ring Reshaped By Planet Around Nearby Star ACS Press Releases(Comets, Planets, and Stars) ACS Press Releases(Black Holes and Supernovae) ACS Press Releases(Nebulae and Galaxies)