The flux density of the galactic object G25.5+/-0.2 has been measured
with the RT-70 radio telescope at 6 cm. It is shown that its intensity
has remained virtually constant for 20 years. If the object is identi
fied with a ring nebula around a blue supergiant with a high mass loss
rate, this result implies that the emission measure has nor changed o
ver the last 20 years.