VLBI observations of 3C 279 at 230GHz

The measured nonzero closure phases on triangles including stations in Arizona, California, and Hawaii indicate that the source structure is spatially resolved. We find an unusual inner jet direction at scales of ~1pc extending along the northwest-southeast direction (P.A.=127{deg}+/-3{deg}), as opposed to other (previously) reported measurements on scales of a few parsecs showing inner jet direction extending to the southwest.

The 1.3mm structure corresponds closely with that observed in the central region of quasi-simultaneous super-resolution Very Long Baseline Array images at 7mm. The closure phase changed significantly on the last day when compared with the rest of observations, indicating that the inner jet structure may be variable on daily timescales. The observed new direction of the inner jet shows inconsistency with the prediction of a class of jet precession models.