Updated Proper Motion of the Neutron Star in the Supernova Remnant Cassiopeia A

Understand

In this paper, we present updated estimates of the velocity of the neutron star (NS) in the supernova remnant (SNR) Cassiopeia A using over two decades of Chandra observations.

• We use two methods: 1.) recording NS positions from dozens of Chandra observations, including the astrometric uncertainty estimates on the data points but not correcting the astrometry of the observations, and 2.) correcting the astrometry of the 13 Chandra observations that have a sufficient number of point sources with identified Gaia counterparts.
• For method #1, we observe a heliocentric velocity of 275 $\pm$ 121 km/s, with an angle of 177 $\pm$ 22 degrees east of north.
• For method #2, we observe a heliocentric velocity of 436 $\pm$ 89 km s$^{-1}$ at an angle of 158 $\pm$ 12 degrees.