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NIRSpec Overview Jeff Valenti 2006 May 19 TIPS/JIM Vertical Field Position (arcmin) Instrument Apertures 4 TFI FGS 2 0 -2 NIRCam NIRSpec MIRI -4 -8 -6 -4 -2 0 2 4 Horizontal Field Position (arcmin) 6 8 Multi-Object Spectroscopy Schematic Light Path Telescope Focus f/20 Pickoff Mirror Filer Wheel Fore optics Grating Wheel MSA f/12.5 Collimator Detectors f/5.67 Camera Optical Components Collimator Filter Wheel Coupling Optics Optical Bench Camera Fore Optics Detectors Grating Wheel Integral Field Unit Micro Shutter Array Focus Mirrors Light Path Movie Configurations Filter Wheel Grating Wheel 0.96 - 1.24 Mirror 0.78 - 2.10 Mirror Clear (0.6 - 5.0) R=100 Prism >1.0 (1.0 - 5.0) R=100 Prism >0.7 (0.7 - 1.4) R=1000 Grating #1 >1.0 (1.0 - 1.8) R=1000 Grating #1 >1.7 (1.7 - 3.0) R=1000 Grating #2 >2.9 (2.9 - 5.0) R=1000 Grating #3 >0.7 (0.7 - 1.4) R=2700 Grating #4 >1.0 (1.0 - 1.8) R=2700 Grating #4 >1.7 (1.7 - 3.0) R=2700 Grating #5 >2.9 (2.9 - 5.0) R=2700 Grating #6 Fixed Apertures Spatial 3.5”x0.2” 3.5”x0.2” Dispersion 4”x0.4” 2”x0.1” 3.5”x0.2” Integral Field Unit (Image Slicer) Q1 Q2 10 Microshutter Array Q3 Q4 10 4365171 250K Shutters 10 Magnet Sweep and Shutter Addressing QuickTime™ and a YUV420 codec decompressor are needed to see this picture. Microshutters Facing the Detectors Facing the Sky Open Area: 0.20” (spectral) x 0.45” (spatial) Shutter Pitch: 0.26” (spectral) x 0.51” (spatial) MSA bars are 0.06” wide Shutter Throughput 1.4 μm 2.4 μm 4.0 μm • Better throughput near center of each shutter • Better flux calibration where gradient is shallow Current Issues NIRSpec detectors achieved TRL6 ! Microshutter technology is still evolving Stray light pentrates unbaffled telescope No requirement limiting plate scale changes Prism design may change Specify Target Acquisition Algorithm Develop Prototype of MSA Tool Typically one aperture per target Multiple shutters per aperture Shutter purpose Target Background Closed Used by pipeline Develop Exposure Time Calculator Begin Developing NIRSpec Pipeline