WSJT-X/doc/user_guide/en/astro_data.adoc

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A text box entitled Astronomical Data provides information needed for
tracking the sun or moon, moon, compensating for EME Doppler shift,
and estimating EME Doppler spread and path degradation. Toggle the
*Astronomical data* on the *View* menu to display or remove this window.
image::AstroData_2.png[align="center",alt="Astronomical Data"]
Available information includes the current *Date* and *UTC* time; *Az*
and *El*, azimuth and elevation of the moon at your own location, in
degrees; *SelfDop*, *Width*, and *Delay*, the Doppler shift, full
limb-to-limb Doppler spread, and delay of your own EME echoes; and
*DxAz* and *DxEl*, *DxDop*, and *DxWid*, corresponding parameters for
a station located at the DX Grid entered on the main window. These
numbers are followed by *Dec*, the declination of the moon; *SunAz*
and *SunEl*, the azimuth and elevation of the Sun; *Freq*, your stated
operating frequency in MHz; *Tsky*, the estimated sky background
temperature in the direction of the moon, scaled to the operating
frequency; *Dpol*, the spatial polarization offset in degrees; *MNR*,
the maximum non-reciprocity of the EME path in dB, owing to spatial
polarization; and finally *Dgrd*, an estimate of the signal
degradation in dB, relative to the best possible time with the moon
at perigee in a cold part of the sky.
The state of the art for establishing three-dimensional locations of
the sun, moon, and planets at a specified time is embodied in a
numerical model of the solar system maintained at the Jet Propulsion
Laboratory. The model has been numerically integrated to produce
tabular data that can be interpolated with very high accuracy. For
example, the celestial coordinates of the moon or a planet can be
determined at a specified time to within about 0.0000003 degrees. The
JPL ephemeris tables and interpolation routines have been incorporated
into _WSJT-X_. Further details on accuracy, especially concerning
calculated EME Doppler shifts, are described in
The sky background temperatures reported by _WSJT-X_ are derived from
the all-sky 408 MHz map of Haslam et al. (Astronomy and Astrophysics
Supplement Series, 47, 1, 1982), scaled by frequency to the (-2.6)
power. This map has angular resolution of about 1 degree, and of
course most amateur EME antennas have much broader beamwidths than
this. Your antenna will therefore smooth out the hot spots
considerably, and the observed extremes of sky temperature will be
less. Unless you understand your sidelobes and ground reflections
extremely well, it is unlikely that more accurate sky temperatures
would be of much practical use.