Presentation #335.05 in the session “The Next Decade Of Nanohertz Gravitational-wave Astrophysics with Pulsar-Timing Arrays”.
We present the fourth data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), which was recently released and is publicly available. The data set consists of of time-of-arrival (TOA) measurements and timing models for 47 millisecond pulsars observed between 2004 and 2017 at the Arecibo Observatory and the Green Bank Telescope. This “12.5-year data set” comes in two varieties. The first, a “narrowband” data set, in which TOAs are measured from many narrow radio-frequency bands for every observation, is very similar in construction and form as our earlier data sets. The second, a “wideband” data set, in which a single TOA and a simultaneous estimate of the dispersion measure (DM) comprise the measurement from each of the broadband observations, is the first pulsar timing array (PTA) data set of its kind. A number of improvements in processing the raw profile data and the TOAs led to a cleaner and more uniformly constructed data set. We report a number of new astrometric, secular, and post-Keplerian measurements as part of updating the pulsars’ timing models. We also perform a thorough comparison of results between the narrowband and wideband data sets, validating the latter’s use for gravitational wave analyses. The results from searching the narrowband data set for a stochastic background of gravitational waves is presented elsewhere.