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Image Stability

Image Stability. ACS SMOV image stability test (prop 9017) went from a cold soak (anti-solar pointing) for 8 orbits to a hot attitude (including off-nominal roll) Nominal jitter (typically about 3 mas RMS and 10 mas peak-to-peak)

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Image Stability

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  1. Image Stability • ACS SMOV image stability test (prop 9017) went from a cold soak (anti-solar pointing) for 8 orbits to a hot attitude (including off-nominal roll) • Nominal jitter (typically about 3 mas RMS and 10 mas peak-to-peak) • Smooth drift at rates up to about 6 mas/hr in both the HRC and WFC (same direction). • Drift may be due to FGS's or to rigid body movement of the ACS wrt the OTA • Similar to image drift rates for other SIs.

  2. Calibration – Flat Fields • L-flat for the F555W filter, the plot is a 4th order least-squares fit to the stellar photometry. • ~10% gradient from upper left to lower right • (Mack, van der Marel, Bohlin, Blakeslee, Cox)

  3. Flat field – Sanity Checks • Ratio of the F555W photometry in the CRJ to the DRZ image, corrected for distortion. • White is 1.10 and black is 0.93. Pixel Map from Geometricdistortion – ratio produces 1% residual

  4. Sensitivity • Inflight sensitivity vs prediction from components HRC WFC

  5. WFC Distortion Calibration • 4th order 2D polynomial fit matches observed distortion well • - RMS residual 1.1 mas (.02 px) • - peak deviation ~ .2 px

  6. WFC CCD Amplifier Cross-talk • Low-level “ghosts” of extended objects mirrored in alternate quadrants • Slight “droop” (fractional e-) in bias level of all 3 alternate amps • Ghosts do not appear to be proportional to target signal Hard (2 e-) stretch of WFC UGC10214 image

  7. Al metal layer reflects long-l photons WFC: Long wave halo F814w F850LP

  8. WFC: Long wave halo F775W F850LP FR1016N - 996 IR Encircled Energy Performance

  9. Optical “Ghosts” Two ghost features have been identified with >0.1% of target energy: WFC CCD to window reflection produces pairs of elliptical ghosts with ~ 0.2% integrated energy F660N [NII] filter produces halos with ~2% of integrated energy due to reflection between its surfaces

  10. Cats-Eye Nebula NGC 6543 (HRC) [OII] 3727 [OIII] 5007 Ha 6563 Ramp filter

  11. Coronagraph performance • Target acquisition functions • executed proposal second time with dithering to determine optimum location under each occulting spot

  12. Coronagraph Dither Results

  13. Coronagraph Performance

  14. SBC – First Light Image Globular star cluster NGC6681. This cluster, with [Fe/H] = -1.5, is rich in Blue Horizontal Branch stars.The image combines first light data taken with three filters F125LP, F150LP, and F165LP.

  15. Solar Blind Channel

  16. CALACS • First generation updates to CALACS & PyDrizzle are complete, software is frozen for distribution in next STSDAS • Includes ST-ECF AXE software for grism/prism Mosaic generated from 18 images of 47 Tuc

  17. WFC • 2x i • 3x z orbits • - “HDF overlay” Grism: 3 orbits HDF-N: i+ z & grism

  18. HDF-N ACS Grism examples Emission-line galaxy with continuum and knots - [OIII] 5007 and H 6563 Redshift z = 0.319 F814AB = 22.5 (WFC 2x i + 3x z orbits, 3 grism orbits)

  19. HDF-N SN2002dc • Identified from difference imaging with WFPC2 HDFN WFC 2x i + 3x z orbits, 3 grism orbits Galaxy & SN z=0.475

  20. HDF-N SN2002dc • Galaxy and SN at z=0.48 • SN mag. is 22.7 (i) • Type I (probably Ia) Galaxy & SN z=0.475

  21. SN2002dd • Identified from extracted spectra ! Galaxy z=0.79 SnIa z=1.06

  22. HDF-N SN2002dd • Follow-up with DD proposal

  23. Cool Image – A1689 Courtesy ACS Science Team

  24. Image Stability

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