Let's imagine we're at ground station trying to receive UHF signal transmitted from moon at 433 / 2400 MHz. Our antenna with 25dB gain (circular polarization) points to the moon. Our LNA has 1dB NF.
What realistic spectral power density of noise we should expect in this situation?
I am interested in realistic estimation - not counting on just temperature of receiver/moon. We have cosmic radio background - solar, galactic, both directly and reflected... We have antenna's side-lobes picking signals from elsewhere... We have hot moon that is NOT covering whole main lobe of the antenna. There must be other tricks which affect the results which you are aware of and I am not.