2010MNRAS.404L...1T

We suggest a revised distance to the supernova remnant G109.1-1.0 (CTB109) and its associated anomalous X-ray pulsar (AXP)1E2259+586 by analysing 21-cm Hi-line and ¹²CO-line spectra of CTB109, Hii region Sh152 and the adjacent molecular cloud complex. CTB109 has been established to be interacting with a large molecular cloud (recession velocity at v = -55km/s). The highest radial velocities of absorption features towards CTB109 (-56km/s) and Sh152 (-65km/s) are larger than the recombination line velocity (-50km/s) of Sh152 demonstrating the velocity reversal within the Perseus Arm. The molecular cloud has cold Hi column density large enough to produce Hi self-absorption (HISA) and Hi narrow self-absorption (HINSA) if it was at the near side of the velocity reversal. Absence of both HISA and HINSA indicates that the cloud is at the far side of the velocity reversal within the Perseus Arm, so we obtain a distance for CTB109 of 4±0.8kpc. The new distance still leads to a normal explosion energy for CTB 109/AXP 1E 2259+586.