Extraterrestrial background

Brightness vI_v for galactic coordinats: a) b>60^o, b) 30^o<b<60^o, c) 10^o<b<30^o, and d) b = 0, l=180^o (from bottom to top).

Cooled mirror background

Telescope mirrors T = 80, 40, 20, 10, 5, 4, 3, and 2 K - thin curves from top to bottom (ε =0.01); dashed curve - ε=0.04, T= 5 K. Thick solid curve shows extraterrestrial background for comparison.