Imaging in visible wavelengths is an important new capability. We propose to use an orthogonal transfer CCD (OTCCD) from MIT Lincoln Laboratory to improve the pointing to 0.05 arcsec, an order of magnitude better than the coarse pointing alone and sufficient to provide long integrations at the diffraction limit of a 2-m telescope. NASA recently demonstrated WASP (the Wallops Arc-Second Pointing system) on a balloon flight in October 2011, a coarse pointing system that kept a dummy telescope (24 ft long, 1500 lbs) stabilized at the 0.25 arcsec level. At visible wavelengths, the diffraction limit of a 1 or 2 m telescope is 0.1 arcsec or 0.05 arcsec, respectively. This means that a large telescope on a balloon should be able to achieve diffraction-limited performance, provided it can be stabilized at a level that is finer than the diffraction limit. In 2009, the SUNRISE balloon mission quantified the wavefront errors with a Shack-Hartmann array and found no evidence of wavefront errors. At those altitudes, the imaging degradation due to atmospheric- induced wavefront errors is virtually zero. NASA s Balloon Program often flies payloads to altitudes of 120,000 ft or higher, above 99.5% of the atmosphere. Inexpensive Demonstration of Diffraction-Limited Telescope from NASA Stratospheric Balloons A strategy has been developed to minimize the total electronic and environmental noise sources to satisfy the scientific requirements. The scientific goals of IRAC are discussed, which are the basis for several important requirements and capabilities of the array camera: (1) diffraction-limited resolution from 2-30 microns, (2) use of the maximum unvignetted field of view of SIRTF, (3) simultaneous observations within the three infrared spectral bands, and (4) the capability for broad and narrow bandwidth spectral resolution. The hybrid DRO readout architecture has the advantages of low read noise, random pixel access with individual readout rates, and nondestructive readout. Three different two-dimensional direct readout (DRO) array detectors are being considered: Band 1-InSb or Si:In (2-5 microns) 128 x 128 pixels, Band 2-Si:Ga (5-18 microns) 64 x 64 pixels, and Band 3-Si:Sb (18-30 microns) 64 x 64 pixels. The Infrared Array Camera for the Space Infrared Telescope Facility (SIRTF/IRAC) is capable of two-dimensional photometry in either a wide field or diffraction-limited mode over the wavelength interval from 2 to 30 microns. International Nuclear Information System (INIS) Wide field and diffraction limited array camera for SIRTF
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