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PLANCK

PLANCK

Name


      PLANCK()

Purpose


      To calculate the Planck function in units of ergs/cm2/s/A

Calling Sequence


      bbflux = PLANCK( wave, temp)

Input Parameters


      WAVE Scalar or vector giving the wavelength(s) in **Angstroms**
              at which the Planck function is to be evaluated.
      TEMP Scalar giving the temperature of the planck function in degree K

Output Parameters


      BBFLUX - Scalar or vector giving the blackbody flux (i.e. !pi*Intensity)
              in erg/cm^2/s/A in at the specified wavelength points.

Examples


      To calculate the blackbody flux at 30,000 K every 100 Angstroms between
      2000A and 2900 A
 
      IDL> wave = 2000 + findgen(10)*100
      IDL> bbflux = planck(wave,30000)
      If a star with a blackbody spectrum has a radius R, and distance,d, then
      the flux at Earth in erg/cm^2/s/A will be bbflux*R^2/d^2

Procedure


      The wavelength data are converted to cm, and the Planck function
      is calculated for each wavelength point. See Allen (1973), Astrophysical
      Quantities, section 44 for more information.

Notes


      See the procedure planck_radiance.pro in
      ftp://origin.ssec.wisc.edu/pub/paulv/idl/Radiance/planck_radiance.pro
      for computation of Planck radiance given wavenumber in cm-1 or
      wavelength in microns

Modification History


      Adapted from the IUE RDAF August, 1989
      Converted to IDL V5.0 W. Landsman September 1997
      Improve precision of constants W. Landsman January 2002



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