Abstract
Wideband timing of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) datasets was first done for the 12.5 yr dataset. This method, where a single time of arrival and a single dispersion measure (DM) are measured using the entire bandwidth of each observation, proved to be invaluable for characterizing the time-varying DM, improving handling of frequency-dependent profile variability, as well as data volume reduction. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) Telescope has been observing most NANOGrav millisecond pulsars (MSPs) at nearly daily cadence (compared to roughly monthly cadence for other NANOGrav observations) since 2019, with the objective of integration into future pulsar timing array datasets. In this paper, we show the results of integration of high-cadence, low-observing-frequency CHIME data with data from the NANOGrav experiment for an isolated MSP PSR J0645+5158 and three binary MSPs: PSR J1012+5307, PSR J2145−0750, and PSR J2302+4442. Using a wideband timing pipeline, which we also describe, we present updated timing results for all four sources, including improved relativistic post-Keplerian measurements for the three binary pulsars in this analysis. For PSR J2302+4442, we report an updated strong detection of Shapiro delay from which we measured a companion mass of 0.35−0.04+0.05M⊙ , a pulsar mass of 1.8−0.3+0.3M⊙ , and an orbital inclination of 80°−2+1 . We also report updated constraints on the reflex motion for PSR J2145−0750 using a combination of Very Long Baseline Array astrometry and our updated measurement of the time derivative of the projected semimajor axis of the pulsar orbit as a prior.