.xlsx file: NRO45m_Efficiency_Measurements_2026_v1.xlsx
The error of the efficiencies is mainly due to an uncertainty of the brightness temperature of the planet.
- Brightness Temperatures (Tb) of the Source (We used temperatures compiled by Shibata 1990)
Mars- 210 K (assumed based on compiled data by Shibata, 5 % error is also assumed)The brightness temperature of Mars is known to change depending on the distance to the Sun (R). According to Ulich (1981), the approximate formula to obtain effective Tb is
Tb(effective) = Tb × (1.524 AU / R)1/2.
The value of R is taken from the “Calendar and Ephemeris” provided by ECO, NAOJ.
- 160±10 K
- 153±11 K (Interpolation of the values at 3.5 mm and 9.6 mm)
- 210 K (assumed based on compiled data by Shibata, 5 % error is also assumed)The brightness temperature of Mars is known to change depending on the distance to the Sun (R). According to Ulich (1981), the approximate formula to obtain effective Tb is
- The Diameter of the Planet
The value is taken from the “Calendar and Ephemeris” provided by ECO, NAOJ. - References
- Shibata, Internal Memorandum: Brightness temperatures of Venus, Mars, and Saturn (1990)
- Ulich, Astron. J. 86, 1619 (1981)