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J/A+A/338/340     Asteroids as IR Standards for ISOPHOT   (Mueller+ 1998)
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Asteroids as far-infrared photometric standards for ISOPHOT
       Mueller T.G., Lagerros J.S.V.
      <Astron. Astrophys. 338, 340 (1998)>
      =1998A&A...338..340M      (SIMBAD/NED BibCode)
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ADC_Keywords: Minor planets ; Polarization ; Spectra, infrared
Keywords: minor planets, asteroids - radiation mechanisms: thermal -
          infrared: solar system

Abstract:
    Asteroids are used as far-IR calibrators for the imaging
    photopolarimeter ISOPHOT on board the Infrared Space Observatory ISO.
    For the 10 selected objects we compiled a large uniform database of
    678 individual observations, ranging from 7-2000{mu}m. Applying a new
    thermophysical model to the observations we derived thermal properties
    of the selected asteroids, based on spin-vector solutions, direct size
    measurements and the HG-magnitude system. Our investigations indicate
    very rough surfaces, reflected in the beaming effect, and very low
    levels of heat conduction, expressed in thermal inertias between 5 and
    25J/m^2^/s^0.5^/K. Due to scattering processes in the porous
    regolith, the emissivity varies significantly with wavelength. In case
    of Vesta we find emissivities as low as 0.6 in the
    far-IR/submillimetre region. By entering the combined results into the
    thermophysical model we defined new photometric standards for the
    far-IR. The absolute accuracy for thermal flux or lightcurve
    predictions is 5-10% for the first category objects and 10-20% for the
    secondaries. The methods and procedures discussed here are included in
    the first update of the ISOPHOT calibration in 1998.

Description:
    Thermal emission observations of 10 selected asteroids. Mid- and
    far-IR data compiled from a number of sources into uniform database.
    The table consists of 678 individual observations, ranging from 7 to
    2000 microns. Inband fluxes have been converted to monochromatic flux
    densities.

File Summary:
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  FileName Lrecl Records  Explanations
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ReadMe        80       .  This file
table7.dat    61     678  Thermal emission observations of 10 selected asteroids
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See also:
  II/190 : IRAS Minor Planet Survey (IMPS) (Tedesco 1992)
  http://cadcwww.dao.nrc.ca/jcmt : The JCMT archive

Byte-by-byte Description of file: table7.dat
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   Bytes Format Units   Label     Explanations
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   1-  4  I4    ---     Asteroid  [1/532] Asteroid number. See Note (1)
   6- 19  F14.6 d       JD        Julian Date
  21- 27  F7.2  um      lambda    [7.7,2000] Wavelength
  29- 37  F9.4  Jy      flux      Monochromatic flux
  39- 46  F8.4  Jy    e_flux      Flux error
  48- 61  A14   ---     Inst      Telescope and instrument. See Note (2)
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Note (1): The IAU designation (number and name)
            1 Ceres
            2 Pallas
            3 Juno
            4 Vesta
           10 Hygiea
           54 Alexandra
           65 Cybele
          106 Dione
          313 Chaldaea
          532 Herculina
Note (2): Telescope and instrument:
            HHT: Heinrich-Hertz-Telescope
           IRAS: Infrared Astronomical Satellite
           IRTF: Infrared Telescope Facility
    ISO/ISOPHOT: Infrared Space Observatory / Imaging-Photopolarimeter
     JCMT/UKT14: James Clerk Maxwell Telescope / United Kingdom Telescope,
                  Cryostat No. 14-Bolometer
      UKIRT/MAX: United Kingdom Infrared Telescope / Mid-Infrared Array
                  eXpandable-Camera
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Acknowledgements: Johan Lagerros <jl@astro.uu.se>

References:
  Altenhoff W.J., Baars J.W.M., Schrami J.B. et al. 1996A&A...309..953A
  Lebofsky L.A., Sykes M.V., Tedesco E.F. et al., 1986Icar...68..239L
  Mueller, T., 1997, Ph.D. thesis, Ruprecht-Karls-Universitat, Heidelberg
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(End)          Johan Lagerros [Uppsala Astronomical Observatory]     08-Sep-1998