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  • 1
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    An infrared imaging study of galaxies in the local universe (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This poster was a preliminary report on a survey of galaxies in the local universe at J and K using a NICMOS3 256 x 256 infrared photometric camera attached to the 61 inch telescope on Mt. Bigelow. Deep images are being obtained for a representative sample of galaxies in the Uppsala General Catalogue. Structural and color parameters are determined for a wide variety of galactic types. These data should prove to be valuable in characterizing stellar populations within disks and bulges, determining if IR-active galaxies have unusual global as well as- nuclear properties, and understanding the effects of evolution and redshift dimming in distant galaxies.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Airborne Astronomy Symposium on the Galactic Ecosystem: From Gas to Stars to Dust, Volume 73; p 195-196
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Direct 75 milliarcsecond images from the Multiple Mirror Telescope with adaptive optics (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We report results from an adaptive optics system designed to provide imaging at the diffraction limit of resolution in the near-infrared at the Multiple Mirror Telescope (MMT). For the present experiment, the aperture consisted of five of the six primary mirrors of the MMT, operating as a coherently phased array. The largest components of the atmospherically induced wave-front aberration are the fluctuations in mean phase between the segments. These errors were derived in real time from the Fourier transform of short-exposure stellar images at 2.2 microns and corrected at an image of the telescope pupil with piston motion from a segmented adaptive mirror. At a correction rate of 43 Hz, this level of adaptive control resulted in an integrated image with a clear diffraction-limited component of 0.075 arcsec FWHM. This stabilized component is present directly in the light arriving at the detector and is not the result of postprocessing. We discuss future improvements to our adaptive wave-front control and its application to astronomical observations.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 402; 2; p. L81-L84.
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Near-infrared stellar-occultation predictions for Uranus and Neptune - 1987-1990 (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Stellar-occultation predictions are presented for Uranus and Neptune covering the period 1987-1990, based on automated scans of R and I plates taken with the UK Schmidt Telescope in Australia. These scans have revealed many late-type or highly reddened stars suitable for stellar-occultation observations at 2.2 microns that were missed in previous searches of yellow-sensitive astrographic plates (Mink and Klemola, 1985). Comparisons involving several hundred stars measured by Mink and Klemola (1985) indicate that the internal random errors in the stellar positions estimated here are less than about 0.2 arcsec, comparable to the precision reached using conventional astrographic methods. In addition, JHK photometry was obtained for many of the Neptune stars, which is used to establish an empirical (I-K) vs (R-I) calibration for the remaining occultation candidates, and thus provide estimates of their K magnitudes.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 95; 562-575
    Format: text
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