ONE OF THE SEASON'S most impressive television programs was a 51-hour-long series that ended last week. It featuered, among others, Griffin Bell, Patricia Roberts Harris, Theodore Sorenson, Paul Warnke and a number of senators. It was, of course, WETA-TV's unprecedented converge of the confirmation hearings for most members of the Carter cabinet. Co-produced by Channel 26 and WNET/13 of New York, the live and delayed broadcasting Service. Thus for the first time citizens everywhere could sit in on these important hearings themselves, and did not have to gauge the nominees entirely form newspapers' summaried and fragments of film on the evening news.

It was a remarkable public service, epitomizing the kind of extended converage that only public broadcasting can provide. Last month's Bell System presentation on the black heritage, "This Far By Faith," was another example of superb non-commercial programming. There is also a rich range of regular offering from "Upstairs, Downstairs" and "The Palisers" to classical music and "Washington Week in Review." The absence of commericals, though, does have another side: It makes such programming dependent on ample public support. The confirmation hearings could be brought to you, for instance, because Channel 26 got funds from the Corporation for Public Broadcasting, the Ford Foundation and other public stations.

Next week WETA and WETA-TV are launching their annual intensive membership campaign. The stations already enjoy impressive community support, with about 75,000 members out of the roughly 350,000 area households that tune in regularly or occasionally. Last year viewers ocntributed more than $1.7 million, slightly less than one-fourth of the two stations' total budget. This year even more is required to sustain high-quality public broadcasting here. For only $15, tax-deductible, a new or renewed membership in WETA is a sound investment - and whose benefits can be seen and heard everyday.