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Trace tilt evolution Trace shape New traces New evolution code Bimodal behavior Remaining work

Trace tilt evolution Trace shape New traces New evolution code Bimodal behavior Remaining work. Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS) with Don Lindler, Ralph Bohlin, Phil Hodge, Nadia Dencheva, Sherie Holfeltz.

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Trace tilt evolution Trace shape New traces New evolution code Bimodal behavior Remaining work

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  1. Trace tilt evolution Trace shape New traces New evolution code Bimodal behavior Remaining work Time-Dependent Spectral Traces for the STIS First Order ModesLinda Dressel (INS)with Don Lindler, Ralph Bohlin, Phil Hodge, Nadia Dencheva, Sherie Holfeltz Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  2. A grid of reference file traces is placed on an (flt, crj) image as the framework along which interpolation will be done to produce spectral extractions (x1d), rectified images (x2d) Problem: x2d images still have some tilt Row does not come from one location along the slit  Random changes, systematic changes in traces? Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  3. The tilt of the traces has been evolving steadily over time, showing clockwise rotation on the detector G430L spectral traces at the center of the detector over the lifetime of STIS, along with the reference file trace Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  4. Rotation rates of the CCD L grating traces(positive = clockwise) Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  5. CCD traces have the same shape: Trace minus linear fit for G230LB, G430L, G750L, G750M(6581, 6768, 8561) Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  6. G140L: 6 feb 1999, CAL/STIS 7937 (o53001*) GD71 (1 star, 20 steps along slit) • G140L, USEAFTER Oct 01 1996 (for aperture at ~ +3") • G140L, USEAFTER Mar 15 1999 (for aperture at ~ -3"): rotated to compensate for MSM change G230L: 2 Sep 1997, CAL/STIS 7667 (o46j01*) NGC346-368 (3 stars, 8 steps) G230L G230LB: 13 Feb 1998, CAL/STIS 7665 (o45p02*) HD120315 (1 star, 33 steps) • G230LB G430L: rotation of G230LB G750L: rotation of G230LB New traces (rotated as needed)  Improved trace reference files for L modes (delivery imminent) with specified MJD, rotation rate Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  7. CALSTIS 2.21b reads two new columns in the SPTRCTAB: • MJD • DEGPERYR (rotation rate; 0 if not measured for that grating/cenwave) It reads the MJD of the science exposure. It computes the difference in dates and the consequent trace rotation. It applies that rotation to the traces before applying them to the (flt,crj) image. New Code: OPUS 2006.4, including CALSTIS 2.21b (released 28 June 2006)STSDAS, including CALSTIS 2.21b (to be released in fall 2006) Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  8. Comparison of “traces” made from x2d files: G140L (low position) OLD REDUCTION: EARLY, LATE NEW REDUCTION: EARLY, LATE Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  9. Comparison of “traces” made from x2d files: G430L (center) OLD REDUCTION: EARLY, LATE NEW REDUCTION: EARLY, LATE Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  10. COMPLICATION! In this case, there are two evolutionary tracks of trace tilt vs time, both showing clockwise rotation on the detector G750M(6768) spectral traces at the center of the detector over the lifetime of STIS, along with the reference file trace Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  11. Grating tilt is set by 3 cylinders • Cylinder settings were changed on July 21, 1997 • Only one exposure in G750M(6768) plot had the early settings • Virtually all STIS GO data have been taken after the change Plot: SHIFTA2 vs date (square: low evolution track, triangle: high evolution track) Population on the two evolutionary tracks of trace tilt vs time is predicted by SHIFTA2, the measurement of the Y position of the wavecal image on the detector The higher track is very rarely populated by exposures with central wavelengths 6581, 8561 Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

  12. Remaining Work • Delivery of the new trace reference files for the L modes • Completion and delivery of new trace reference files for G750M(6581), G750M(6768), G750M(8561) • Implementation of a "tweak-trace" post-processing tool that measures the science image to determine the rotation to apply to the reference file traces • Completion of an Instrument Science Report Time-Dependent Spectral Traces for the STIS First Order Modes Linda Dressel (INS)

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