We have observed six high-mass star-forming regions in the ^ { 2 } \Pi _ { 3 / 2 } , J = 7 / 2 lines of OH using the GBT in order to investigate whether the magnetic field , and hence the density , measured in absorption differs from that implied by maser Zeeman splitting .
We detect absorption in both the 13441 and 13434 MHz main lines in all six sources .
Zeeman splitting in the F = 3 ^ { + } \rightarrow 3 ^ { - } absorption line in W3 ( OH ) implies a line-of-sight magnetic field strength of 3.0 \pm 0.3 mG .
This is significantly less than full magnetic field strengths detected from OH maser Zeeman splitting , suggesting that OH maser regions may be denser than the non-masing OH material by a factor of several .
Zeeman splitting is not detected in other sources , but we are able to place upper limits on B _ { \parallel } of 1.2 mG in G10.624 - 0.385 and 2.9 mG in K3 - 50 .
These results are consistent with a density enhancement of the masers , but other explanations for the lower magnetic field in absorption compared to maser emission are possible for these two sources .
Absorption in one or both of the 13442 and 13433 MHz satellite lines is also seen in four sources .
This is the very first detection of the ^ { 2 } \Pi _ { 3 / 2 } , J = 7 / 2 satellite lines .
Ratios of satellite-line to main-line absorption suggest enhancement of the satellite lines from local thermodynamic equilibrium values .
Masers are seen in the F = 4 ^ { + } \rightarrow 4 ^ { - } and 3 ^ { + } \rightarrow 3 ^ { - } transitions of W3 ( OH ) and the 4 ^ { + } \rightarrow 4 ^ { - } transition of ON 1 .
A previously undetected 4 ^ { + } \rightarrow 4 ^ { - } maser is seen near -44.85 km s ^ { -1 } in W3 ( OH ) .