From the dark skies of the countryside outside Washington, a dirty old snowball has emerged in the starry western sky. Comet Bradfield is still there.

About two weeks ago, Bradfield reached its maximum brightness, sending astronomers to capture the sight with binoculars and telescopes. Despite losing some of its luminous splendor, the comet remains a well-placed celestial object for area residents. It looks like a faint fuzz early in the evening, just to the south of due west.

Geoff Chester, an astronomer for the Einstein Planetarium at the Smithsonian Institution's National Air and Space Museum, said that Bradfield will be visible with binoculars through the end of the year and that amateur astronomers will be able to see it with a telescope until spring.

The comet is expected to lose some of its brilliance this week. A full moon is due on Saturday, and, astronomers say, bright moonlight will make the comet more difficult to see. Chester suggests waiting until the moon wanes next week to get a clearer view of the comet. Bradfield is expected to be at +5.7 magnitude, a value indicating that it will be barely visible to the naked eye.

Bradfield was discovered by an Australian astronomer, William Bradfield, in August, and it ranks among a bumper crop of new-found comets. The International Astronomical Union, based in Cambridge, Mass., officially has recorded 32 discoveries so far in 1987. The old record, set in 1983, was 23 comet discoveries.

The last two comets were spotted Nov. 22 in Japan. They are named Ichimura and Furuyama, but they cannot be readily viewed here, mainly because they are too dim.