PLANET

##
PLANET

            [ASTRO\]PLANET  [name]  [/DRAW [Arg1 ... ArgN]] [/EPHEMERIS FileName
        NEW|APPEND] [/QUIET] [/BEAM beam]

        Compute the coordinates of a Solar System  object.  Known  objects  are:
        MOON, SUN, MERCURY, VENUS, MARS, JUPITER, SATURN, URANUS, NEPTUNE. If no
        name is entered, all objects are selected. The Option /DRAW is  used  to
        plot the object symbol on the screen.

        The  PLANET command output the planet coordinates (apparent RA, apparent
        DEC, Azimuth and Elevation at time of computation) and the sun  distance
        (with  a  warning  message  if this distance os lower than the telescope
        limit). PLANET also indicates the geocentric (DE) and heliocentric  (DS)
        distances  of the object (in AU), the apparent minor and major diameters
        (Min and Maj in arcsec), the position angle of the central meridian (PA,
        east  from north, in degrees), the brightness temperature (TB in K), the
        flux (S in Jy) at the current frequency, the  frequency  (in  GHz),  the
        beam  (in  arcsec), the main beam temperature (Tmb in K), the associated
        flux (in Jy) and the planet size convolved with the telescope beam (size
        in arcsec).

        For the Moon, the Sun and Mercury, the brightness temperature is a fixed
        value.  For Mars, the brightness temperature is scaled according to  the
        heliocentric distance.  For Venus, the brightness temperature is comput-
        ed at the current frequency using a reference  value  at  100GHz  and  a
        spectral index.

        As  of July 2023, for Jupiter, Saturn, Uranus and Neptune the brightness
        temperature is interpolated from tabulated values of model spectra. (Be-
        fore  that, Jupiter and Saturn brightness temperatures were fixed values
        while a spectral index was taken into account for Uranus and Neptune).

        The method used to get the planet brightness temperature is given in the
        command  output  and in the sic variable ASTRO%PLANET%TB_METHOD (MODEL =
        interpolation from model, SPIDX = computed from value and  spectral  in-
        dex)

        The  accuracy of the planet brightness temperatures as computed in ASTRO
        is estimated to be on the order of 5%.

        The frequency can be entered by  updating  the  variable  FREQUENCY  (in
        GHz).

        PLANET /QUIET suppresses all the printouts on the screen.

        Without  the option /BEAM, the beam used is deduced from the current ob-
        servatory and frequency. User may override this default  by  giving  non
        zero beam size (in arcsec) as an argument of the /BEAM option.

        All  these parameters are also also written in SIC variables, in the AS-
        TRO%PLANET% structure. Just enter EXAMINE ASTRO%PLANET% to  get  a  com-
        plete list of these variables.

Subsections

- PLANET /DRAW
- PLANET /EPHEMERIS