Transcript EIS instrument throughput update

EIS Sensitivity Update
John Mariska
NRL
3-5 Feb 2003
020116EIS_JTM.1
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
020116EIS_JTM.2
EIS Effective Area Curves
020116EIS_JTM.3
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
020116EIS_JTM.4
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
020116EIS_JTM.5
EIS Model Sample Output
020116EIS_JTM.6
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
020116EIS_JTM.7