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The next generation exposure time calculator for JWST Recommendations and science concept. The MESA ETC WG: Elizabeth Barker (coordinator), Klaus Pontoppidan, Mike Regan, Diane Karakla , Christine Chen, Jen Lotz , Massimo Robberto , Andre Martel, Vicki Laidler , Chris Hanley.
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The next generation exposure time calculator for JWSTRecommendations and science concept The MESA ETC WG: Elizabeth Barker (coordinator), Klaus Pontoppidan, Mike Regan, Diane Karakla, Christine Chen, Jen Lotz, Massimo Robberto, Andre Martel, Vicki Laidler, Chris Hanley
We are required to support all JWST modes. (S&OC level 3) NIRCAM NIRSPEC MIRI NIRISS FGS • Imaging • Lyotcoronagraphy • 4QPM coronagraphy • Medium resolution IFU • Low-resolution single object • Target Acq • Imaging • Wide-field slitless spectroscopy • Single-object slitless spectroscopy • Aperture masking • Target Acq • Guiding • Calibration • Imaging • Coronagraphy • Target Acq • MOS PRISM • MOS R=1000 • MOS R=2700 • IFU PRISM • IFU R=1000 • IFU R=2700 • Fixed slit • Target Acq
TBD ETC development is a close collaboration between the ETCWG and the SSB. Detailed test implementation “Scamp” Production ETC WIT ETCWG SSB Level 5 Requirements (how) “blue sky” concept ETCWG Recommendation Level 4 Requirements (what)
The ETC should use a three-dimensional (two spatial and one spectral) framework. Recommendation
The ETC should use a grid of reference PSFs, for instance as generated by the WebbPSF tool. Recommendation
A 3D ETC enables support for all JWST observing modes. A few arcsec Y Wavelength X
The noise propagation should include correlated noise. Recommendation
The ETC models correlated detector noise. Total flux rate in measurement Flux rate in pixel i scalar weight of pixel i Variance of measurement covariance matrix of pixels (1,2,...,N)
Example: Aperture photometry A = extraction region/aperture B = sky region Aperture correction Pixel flux rate in aperture Pixel flux rate in background Pixel weights Negative because the background is subtracted
The ETC requires 3 classes of input. Input 1 Input 3 Input 2
The ETC engine may have to support several clients. APT Web applet/form Stand-alone app ETC engine A python library
The ETC engine should have a stable API, capable of supporting different clients, including APT, a user web form and a standalone graphical application. Recommendation