What time was the sunset on 21 march?

The U.S. Naval Observatory has a "Sunrise & Sunset" calculator on their web site, which I have linked below. Go there, select your state and type in your city name (for anyplace in the USA) or enter your latitude and longitude (anyplace else in the world) and it will generate all the pertinent data for your location for any date you specify.

Southbury isn't in their database, but Newtown is very close...

U.S. Naval Observatory
Astronomical Applications Department
Sun and Moon Data for One Day

The following information is provided for Newtown, Fairfield County, Connecticut (longitude W73.3, latitude N41.4):

Sunday 23 March 2008 Eastern Daylight Time SUN Begin civil twilight 6:23 a.m. Sunrise 6:51 a.m. Sun transit 1:00 p.m. Sunset 7:09 p.m. End civil twilight 7:37 p.m. MOON Moonrise 8:23 p.m. on preceding day Moon transit 1:55 a.m. Moonset 7:18 a.m. Moonrise 9:27 p.m. Moonset 7:42 a.m. on following day

Phase of the Moon on 23 March: waning gibbous with 96% of the Moon's visible disk illuminated.

Full Moon on 21 March 2008 at 2:40 p.m. Eastern Daylight Time.