Venus Observations at 40 and 90 GHz with CLASS

TL;DR

This paper reports the most precise measurements to date of Venus's brightness temperature at 40 and 90 GHz using the CLASS telescope, confirming atmospheric models with CO2 and trace gases.

Contribution

First precise measurements of Venus's brightness temperature at these frequencies, validating atmospheric models with trace gases.

Findings

Measured brightness temperatures: 432.3 K at 40 GHz and 355.6 K at 90 GHz.

No phase dependence observed in the temperature measurements.

Results are consistent with CO2-dominant atmospheric models including trace gases.

Abstract

Using the Cosmology Large Angular Scale Surveyor, we measure the disk-averaged absolute Venus brightness temperature to be 432.3 $\pm$ 2.8 K and 355.6 $\pm$ 1.3 K in the Q and W frequency bands centered at 38.8 and 93.7 GHz, respectively. At both frequency bands, these are the most precise measurements to date. Furthermore, we observe no phase dependence of the measured temperature in either band. Our measurements are consistent with a CO$_2$-dominant atmospheric model that includes trace amounts of additional absorbers like SO$_2$ and H$_2$SO$_4$.