Astronomical Satellite

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform

Hideo Matsuhara - One of the best experts on this subject based on the ideXlab platform.

  • albedo properties of main belt asteroids based on the all sky survey of the infrared Astronomical Satellite akari
    The Astrophysical Journal, 2013
    Co-Authors: Fumihiko Usui, Sunao Hasegawa, Masateru Ishiguro, D Kuroda, Thomas G Muller, Takafumi Ootsubo, Toshihiro Kasuga, Hideo Matsuhara
    Abstract:

    We present an analysis of the albedo properties of main belt asteroids (MBAs) detected by the All-Sky Survey of the infrared Astronomical Satellite AKARI. The characteristics of 5120 asteroids detected by the survey, including their sizes and albedos, were cataloged in the Asteroid Catalog Using AKARI (AcuA). Size and albedo measurements were based on the standard thermal model, using inputs of infrared fluxes and absolute magnitudes measured at optical wavelengths. MBAs, which account for 4722 of the 5120 AcuA asteroids, have semimajor axes of 2.06-3.27 AU, except for the near-Earth asteroids. AcuA provides a complete data set of all MBAs brighter than the absolute magnitude of H 20 km. We confirmed that the albedo distribution of the MBAs is strongly bimodal as was already known from the past observations, and that the bimodal distribution occurs not only in the total population, but also within inner, middle, and outer regions of the main belt. The bimodal distribution in each group consists of low-albedo components in C-type asteroids and high-albedo components in S-type asteroids. We found that the small asteroids have much more variety in albedo than the large asteroids. In spite of the albedo transition process like space weathering, the heliocentric distribution of the mean albedo of asteroids in each taxonomic type is nearly flat. The mean albedo of the total, on the other hand, gradually decreases with an increase in semimajor axis. This can be explained by the compositional ratio of taxonomic types; that is, the proportion of dark asteroids such as C- and D-types increases, while that of bright asteroids such as S-type decreases, with increasing heliocentric distance. The heliocentric distributions of X-subclasses: E-, M-, and P-types, which can be divided based on albedo values, are also examined. P-types, which are the major component in X-types, are distributed throughout the main belt regions, and the abundance of P-types increases beyond 3 AU. This distribution is similar to that of C- or D-types.

  • The infrared Astronomical Satellite AKARI: overview, highlights of the mission
    Space Telescopes and Instrumentation 2008: Optical Infrared and Millimeter, 2008
    Co-Authors: Hiroshi Murakami, Hideo Matsuhara
    Abstract:

    The AKARI, Japanese infrared Astronomical Satellite, is a 68.5 cm cooled telescope with two focal-plane instruments providing continuous sky scan at six wavelength bands in mid- and far-infrared. The instruments also have capabilities of imaging and spectroscopy in the wavelength range 2-180 μm in the pointing observations occasionally inserted into the continuous survey. AKARI was launched on 21st Feb. 2006, and has performed the all-sky survey as well as 5380 pointing observations until the liquid helium exhaustion on 26th Aug. 2007. The all sky survey covers more than 90 percent of the entire sky with higher spatial resolutions and sensitivities than the IRAS. First version of the infrared source catalogue will be released in 2009. Here we report the overview of the mission, highlights on the scientific results as well as the performance of the focal-plane instruments. We also present the observation plan with the near infrared camera during the post-helium mission phase started in June 2008.

  • Evaluation of the mid-and near-infrared focal plane arrays for Japanese infrared Astronomical Satellite ASTRO-F
    IR Space Telescopes and Instruments, 2003
    Co-Authors: Daisuke Ishihara, Hideo Matsuhara, Takashi Onaka, Takehiko Wada, Hidenori Watarai, Hirokazu Kataza, Munetaka Ueno, Kazunori Uemizu, Woojung Kim, Naofumi Fujishiro
    Abstract:

    We report on the extensive tests to characterize the performance of the infrared detector arrays for the Infrared Camera (IRC) on board the next Japanese infrared Astronomical Satellite, ASTRO-F. The ASTRO-Fwill be launched early 2004 and the IRC is one of the focal plane instruments to make observations in 2-26μm. For the near-infrared observations of 2-5μm, a 512x412 InSb array will be employed, while two 256x256 Si:As arrays will be used for the observations of 5-26μum in the IRC. Both arrays are manufactured by Raytheon. To maximize the advantage of the cooled telescope and extremely low background radiation conditions in space, the dark current and readout noise must be minimized. The heat dissipation of the arrays also has to be minimized. To meet these requirements and achieve the best performance of the arrays, we optimized the array driving clocks, the bias voltage, and the supply currents, and evaluated the temperature dependence of the performance. In particular, we found that the voltage between the gate and source of the FET of the multiplexer SBRC-189 had a strong dependence on temperature. This effect becomes a dominant source for the noise unless the temperature is kept within 20mK. We have achieved the readout noises of about 30e- and 40e- with the correlated double sampling for the flight model readout circuits of the InSb and Si:As arrays, respectively. These noises ensure that the background-limited performance can be achieved for the observations of IRC in the 4-26μm range in the current observing scheme. In addition, we are now planning to make scan mode observations by IRC. We have developed a new operation way of the arrays to achieve the stable response and low readout noise in the scanning operation for the first time. The IRC is now installed in the flight model cryostat and the first end-to-end test has just been completed. We report on the expected performance of the IRC together with the array test results.

Nasa - One of the best experts on this subject based on the ideXlab platform.

T Kii - One of the best experts on this subject based on the ideXlab platform.

  • the vlbi space observatory programme and the radio Astronomical Satellite halca
    Publications of the Astronomical Society of Japan, 2000
    Co-Authors: H Hirabayashi, Haruto Hirosawa, Hideyuki Kobayashi, Yasuhiro Murata, Yoshiharu Asaki, I M Avruch, P G Edwards, E B Fomalont, Tsutomu Ichikawa, T Kii
    Abstract:

    The radio astronomy Satellite HALCA was launched by the Institute of Space and Astronautical Science in 1997 February to participate in Very Long Baseline Interferometry (VLBI) observations with arrays of ground radio telescopes. HALCA is the main element of the VLBI Space Observatory Programme (VSOP), a complex international endeavor involving over 25 ground radio telescopes, five tracking stations and three correlators. Simultaneous observations with HALCA's 8 meter diameter radio telescope and ground radio telescopes synthesize a radio telescope over twice the size of the Earth, enabling the highest resolution 1.6 GHz and 5 GHz images to be made. Key word: space vehicles: instruments — techniques: interferometric — radio continuum: galaxies Astronomical Society of Japan • Provided by the NASA Astrophysics Data System

Jiancheng Wang - One of the best experts on this subject based on the ideXlab platform.

  • TWO MICRON ALL SKY SURVEY, INFRARED Astronomical Satellite, AND MIDCOURSE SPACE EXPERIMENT COLOR PROPERTIES OF INTRINSIC AND EXTRINSIC S STARS
    The Astronomical Journal, 2006
    Co-Authors: Xiao-hong Yang, P. S. Chen, Jiancheng Wang
    Abstract:

    We attempt to select new candidate intrinsic and extrinsic S stars in the General Catalogue of Galactic S Stars (GCGSS) by combining data from the Two Micron All Sky Survey, the Infrared Astronomical Satellite, and the Midcourse Space Experiment. Catalog entries are cross-identified, yielding 528 objects, out of which 29 are known extrinsic S stars and 31 are known intrinsic S stars. Their color-color diagrams, (H - [12])-(K [12]) and ( K - [12])-(J - [25]), are drawn and used to identify a new sample of 147 extrinsic and 256 intrinsic S star candidates, while the nature of 65 stars remains identified. We infer that about 38% +/- 10% of the GCGSS objects are of extrinsic type. Moreover, we think that colors such as J - [25] can be used to split off the two categories of S stars, while single colors are not appropriate. The color-color diagrams, such as (H - [12])-(K - [12]) and (K - [12])-(J - [25]), are proven to be powerful tools for distinguishing the two kinds of S stars.

Simone Bianchi - One of the best experts on this subject based on the ideXlab platform.

Astronomical Satellite - 15 days free trial to Access Experts & Abstracts