CAMDEN — Acoustic music duo Castlebay returns for another SoundCheck concert Friday, March 4, at 7:30 p.m. at the Camden Opera House, 29 Elm St. The hour-long concert, rescheduled from January, is sponsored by Oyster River Winegrowers.

Castlebay – the Round Pond duo of Julia Lane and Fred Gosbee – has explored and performed the interwoven music of New England and the Celtic lands for decades. Their concerts often mix poetry and stories with music, their traditional and original songs and tunes accompanied with guitar, Celtic harp, fiddle and woodwinds.

Lane and Gosbee recently published “Bygone Ballads of Maine, Vol. 1 – Songs of Ships & Sailors,” the culmination of years of research. The hardcover book has more than 160 songs with lyrics, tunes and notes plus an extensive appendix of sources and context. Gathered from field recordings, journals and manuscripts made pre-1950 in Maine, most of the material is previously unpublished and has garnered interest far beyond the state’s borders.

Tickets are $10, and advance purchase is encouraged via and 236-3154. The opera house’s choose-your-own ticketing software ensures every-other-row distancing, as well as a couple of seats either side of each party’s reservation. Masks are required in the building.

Doors will open at 7 p.m. SoundCheck also is livestreamed on the opera house’s Facebook page, no admission or link required. The series continues Friday night, March 11, with Hancock County songwriter Chris Ross, performing a solo show.