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EIS Sensitivity Update

EIS Sensitivity Update. John Mariska NRL 3-5 Feb 2003. EIS Effective Areas. First set of flight optics coated at Columbia University and Characterized at Brookhaven Effective areas computed using Measured M 1 reflectivities

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EIS Sensitivity Update

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  1. EIS Sensitivity Update John Mariska NRL 3-5 Feb 2003

  2. EIS Effective Areas First set of flight optics coated at Columbia University and Characterized at Brookhaven • Effective areas computed using • Measured M 1 reflectivities • Measured FL 7 efficiencies (combination of reflectivity and groove efficiency) • Same Al filter transmission as earlier calculations • Al filter mesh transmission factor of 0.85 • Spider transmission factor of 0.80 • CCD QE of 0.80 • Mirror area of 0.5*88.4 • Results are near those used in all earlier EIS sensitivity calculations

  3. EIS Effective Area Curves

  4. EIS Effective Area Data • All data files used to compute the effective area are in the EIS SolarSoft directory $SSW_EIS/response • All data files are text, with #-delimited comments at beginning • Read using data = rd_tfile(file, /nocom, /auto, /conv) • Each data file has a three digit extension—higher numbers are newer, so highest number of each file should be considered current • Key files are • EIS_EffArea_A.001 and EIS_EffArea_B.001 • Procedure for reading effective area files will be placed in $SSW_EIS/idl/cal and will default to taking highest version number of area files • Procedures for using emission measure curves and Chianti data to generate spectra for planning purposes under development

  5. Modeling EIS • Using preliminary sensitivity information, have modeled EIS detectors • Model uses a TRACE 195 Angstrom image to interpolate between quiet Sun and active region differential emission measure curves • For each location in the TRACE image, model computes an emission measure and uses that to synthesize the spectrum along the EIS slit • Thermal, nonthermal, and instrumental broadening included • Includes Poisson statistics on number of arriving photons and converts to photoelectrons and then DN • Adds a pedestal—currently 100 electrons—and a normal distribution of read noise with a standard deviation of 6 electrons • Will be updating to include random Doppler shifts and other delights • Data and detailed description at http://tcrb.nrl.navy.mil/~mariska/eismod

  6. EIS Model Sample Output

  7. EIS Model Implications • Large difference in count rates between the two detectors • For active regions and a 10 s integration, the model predicts • 10,000 to 14,000 DN for Fe XII • 1,500 DN for Fe XV • Observing strategy will need to carefully consider how to handle these differences

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