Congress, as everyone in Washington knows, reconvened Thursday -- that much is indisputable. And as soon as the Chronicler straightens out the end of the holidays for everybody, she'll get back to the new members of that august body.

Today is Epiphany, the last day of Christmas, according to no less an authority than Ronald H. Haines, bishop of the Episcopal Diocese of Washington. "Twelfth Night is a little more difficult," he said, "because -- contrary to modern calendars, which go from midnight to midnight -- liturgical calendars, both Christian and Hebrew, go from sundown to sundown."

Anyway, tomorrow everybody goes back at work.

Now the Chronicler would like to make the work of hostesses, social secretaries, lobbyists et al., simpler by telling you all you need to know about the new members of Congress.

Everybody wants to know first how many extra men are available to sit by extra women at dinner parties. There's good news. Of the 44 new members of the House of Representatives (45 if you count Eleanor Holmes Norton, the District of Columbia's nonvoting delegate), eight men and one woman are widowed, divorced or never married -- provided they haven't upped and wed since the elections. (The Chronicler is unfortunately not able to assure you that some are not informally committed and aren't saying.)

For your black book here are the essential facts about the eligible nine, as provided by Congressional Quarterly.

Barbara-Rose Collins (D-Mich.), born April 13, 1939, and Bud Cramer (D-Ala.), b. Aug. 22, 1947, are both widowed.

Both new congressmen from Minnesota are currently unmarried -- Jim Ramstad, the Republican, b. May 6, 1946, is single; Collin C. Peterson, the Democrat, b. June 29, 1944, is divorced.

The other singles are: Dave Camp (R-Mich.), b. July 9, 1953; Robert E. Andrews (D-N.J.), b. Aug. 4, 1957; John F. Reed (D-R.I.), b. Nov. 12, 1949; Chet Edwards (D-Tex.), b. Nov. 24, 1951; and Bill Orton (D-Utah), b. Sept. 22, 1949.

Second question, how many have children?

Well, apparently, to win a Senate seat, it was necessary to have three children -- all four new senators do.

In the House, 34 new representatives have children. Joan Kelly Horn (D-Mo.) is the clear winner in numbers. Horn, understandably a supporter of child care, has six, all grown, by her first husband.

Other points of interest:

Thirteen of the new members (all in the House) are lawyers and/or law professors: Cramer, Camp, Ray Thornton (D-Ark.), Jim Bacchus (D-Fla.), John W. Cox Jr. (D-Ill.), Jim Nussle (R-Iowa), William J. Jefferson (D-La.), Ramstad, Robert E. Andrews (D-N.J.), Dick Zimmer (R-N.J.), Rick Santorum (R-Pa.), John F. Reed (D-R.I.) and Orton. Anybody surprised?

Seven are in real estate -- investors, brokers etc.: Sens. Larry E. Craig (R-Idaho) and Robert C. Smith (R-N.H.), and Reps. Frank Riggs (R-Calif.), Gary Franks (R-Conn.), Bill Barrett (R-Neb.), David L. Hobson (R-Ohio) and Bill Brewster (D-Okla.).

Three held political office when elected to Congress: Collins, a Detroit city councilwoman; John T. Doolittle (R-Calif.), a state legislator; and Charles Luken (D-Ohio), mayor of Cincinnati.

Farming, a favorite occupation of politicians of the past, is not much in evidence this year. Only Calvin Dooley (D-Calif.) and Charles H. Taylor (R-N.C.) so listed themselves. Craig called himself both a real estate salesman and a farmer.

Five listed themselves as professors, teachers or educational administrators: Sen. Paul Wellstone (D-Minn.) and Reps. Bernard Sanders (I-Vt.), Wayne T. Gilchrest (R-Md.), Maxine Waters (D-Calif.) and Pete Peterson (D-Fla.).

Bankers this year were few. Only Dick Nichols (R-Kan.) and James P. Moran Jr. (D-Va.) admitted to being bankers.

Fortunately, considering the budget deficit, two are accountants: Peterson and Sen. Hank Brown (R-Colo.).

Oh yes, if you want to invite any of the freshmen to dinner, the switchboard number of the Capitol is 202-224-3121, and the telephone operators are very helpful.