2008ApJ...677..292T

We provide a new distance estimate to the supernova remnant (SNR) Kes 73 and its associated anomalous X-ray pulsar (AXP) 1E 1841-045. 21 cm H I images and H I absorption/emission spectra from new VLA observations, and ¹³CO emission spectra of Kes 73 and two adjacent compact H II regions (G27.276+0.148 and G27.491+0.189) are analyzed. The H I images show prominent absorption features associated with Kes 73 and the H II regions. The absorption appears up to the tangent point velocity giving a lower distance limit to Kes 73 of 7.5 kpc, which has previously been given as the upper limit. In addition, G27.276+0.148 and G27.491+0.189 are at the far kinematic distances of their radio recombination line velocities. There is prominent H I emission in the range 80-90 km/s for all three objects. The two H II regions show H I absorption at ∼84 km/s, but there is no absorption in the Kes 73 absorption spectrum. This implies an upper distance limit of ∼9.8 kpc to Kes 73. This corrected larger distance to Kes 73/AXP 1E 1841-045 system leads to a refined age of the SNR of 500-1000 yr, and a ∼50% larger AXP X-ray luminosity.