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The NASA Exoplanet Star (and) Speckle Imager, or NESSI, is expected to be available on WIYN beginning in October, 2016. This new instrument utilizes two electron-multiplying CCD cameras to capture speckle images in two colors simultaneously. Speckle observations provide resolutions at or near the diffraction limit of the telescope allowing companion detection and characterization to delta magnitudes of approximately 5. NESSI will have remote controlled filter wheels in each beam, split by the dichroic at 686.4nm.
The EMCCDs can operate with high sensitivity and low noise even at very fast readout rates, providing high time resolution. The maximum rate of imaging with zero-second exposures for the full 1024x1024 pixel image with no binning is 26fps. By using subwindows and binning, the cameras will operate at higher frame rates (details to be determined).
NESSI will also introduce a new "wide-field" mode that will enable the collection of images with fields of >70 arcseconds. Each 6-slot filter wheel will come with two "narrow-band" speckle filters, two standard SDSS filters, and (currently) two empty slots.
Further information on NESSI can be found on these web pages.
Wide Field Mode Speckle Mode Telescope Focal Plane: Telescope f/#: 6.289 6.289 Plate Scale: 9.374 arcsec/mm 9.374 arsec/mm Focal Lengths: L1 Focal Length: 100mm 30mm L2 Focal Length: 150mm 200mm Optical Path: Tel. Focus: 0mm = 0in 0mm = 0in L1: 100mm = 3.937in 30mm = 1.181in L2: 258.4mm = 10.173in 278.4mm = 10.961in Detector: 150mm = 5.906 200mm = 7.874in Total Length: 508.4mm = 20.016in 508.4mm = 20.016in Detector Image Plane: Magnification from Tel. focal plane: 1.5x 6.67x Pixel Scale (13 micron pixels): 0.0813 arsec/pix 0.0182 arsec/pix Unvignetted Circle Dia.: 56 arcsec 22 arcsec Square Detector FOV: 83 x 83 arcsec 19 x 19 arcsec
1024 x 1024 pixel electron multiplying CCDs (Andor Ixon Ultra 888's). The electron multiplying aspect of EMCCs allows imaging at higher speeds than traditional CCDs because the readnoise is effectively lowered. High speeds are also made possible through shutterless operation in a frame transfer mode.
Filter Wheel A Centeral λ, bandwidth Filter Wheel B Central λ, bandwidth SDSS/u 354.3nm, 32.7nm SDSS/i 765.4nm, 146.4nm SDSS/g 480nm, 151.1nm SDSS/z 943.3nm, 242.7nm SDSS/r 620nm, 143.5nm 716 716nm, 51.5nm 467 467.1nm, 44nm 832 832nm, 40.4nm 562 562.3nm, 43.6nm
NESSI Field Of View
Last modified: 20-Sep-2016 16:49:01 MST
- Observing at WIYN