Full‐Polarization Observations of OH Masers in Massive Star‐forming Regions. I. Data

We present full-polarization VLBA maps of the ground-state, main-line, 2 Π 3/2 , J = 3/2 OH masers in 18 Galactic massive star-forming regions. This is the first large polarization survey of interstellar hydroxyl masers at VLBI resolution. A total of 184 Zeeman pairs are identified, and the corresponding magnetic field strengths are indicated. We also present spectra of the NH 3 emission or absorption in these star-forming regions. Analysis of these data will be presented in a companion paper.