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PSR J1813-1749 is one of the most energetic rotation-powered pulsars known,producing a pulsar wind nebula (PWN) and gamma-ray and TeV emission, but whosespin period is only measurable in X-ray. We present analysis of two Chandradatasets that are separated by more than ten years and recent NICER data. Thelong baseline of the Chandra data allows us to derive a pulsar proper motionmu_R.A.=-(0.067"+/-0.010") yr^-1 and mu_decl.=-(0.014"+/-0.007") yr^-1 andvelocity v_perp~900-1600 km/s (assuming a distance d=3-5 kpc), although wecannot exclude a contribution to the change in measured pulsar position due toa change in brightness structure of the PWN very near the pulsar. We model thePWN and pulsar spectra using an absorbed power law and obtain best-fitabsorption NH=(13.1+/-0.9)x10^22 cm^-2, photon index Gamma=1.5+/-0.1, and0.3-10 keV luminosity Lx~5.4x10^34 erg/s (d/5 kpc)^2 for the PWN andGamma=1.2+/-0.1 and Lx~9.3x10^33 erg/s (d/5 kpc)^2 for PSR J1813-1749. Thesevalues do not change between the 2006 and 2016 observations. We use NICERobservations from 2019 to obtain a timing model of PSR J1813-1749, with spinfrequency nu=22.35 Hz and spin frequency time derivativenudot=(-6.428+/-0.003)x10^-11 Hz/s. We also fit nu measurements from 2009-2012and our 2019 value and find a long-term spin-down ratenudot=(-6.3445+/-0.0004)x10^-11 Hz/s. We speculate that the difference inspin-down rates is due to glitch activity or emission mode switching.

Proper motion, spectra, and timing of PSR J1813-1749 using Chandra and NICER