Abstract We performed very long baseline interferometry (VLBI) observations to measure the trigonometric parallax of H₂O maser sources in the outer massive star-forming region IRAS 23385+6053 using the VLBI Exploration of Radio Astrometry (VERA) in Japan. The annual parallax is =0. 460 0. 086 mas, which corresponds to a distance of 2. 17^+0. 50-₀. ₃₄ kpc, roughly half the kinematic distance of 4. 9 kpc reported in previous studies. The proper motion of IRAS 23385+6053 is obtained to be (, ) = (-3. 73 0. 53, -2. 07 0. 73) mas yr^-1. Based on VLBI astrometry result, we derived the physical properties of molecular clouds in which H₂O masers have been detected, including IRAS 23385+6053 in the Cepheus and Cassiopeia region. We discuss the line-of-sight structures of the giant molecular clouds using the trigonometric distances obtained from the H₂O maser sources. Our results suggest that molecular clouds in the Perseus arm extend over approximately 2 kpc at the Cepheus and Cassiopeia region.
Hamada et al. (Thu,) studied this question.