FAST interstellar scintillation observation of PSR B1929+10 and PSR B1842+14

In this paper, we present the Five-hundred-meter Aperture Spherical radio Telescope (FAST) observations of PSRs B1929+10 and B1842+14. Through analysis of the pulsars' scintillation pattern, we detected the known scintillation arc from PSR B1929+10 and two previously undetected scintillation arcs from B1842+14. We find that the B1929+10 arc's curvature scales with observing frequency as eta(-) proportional to nu(-2.1 +/- 0.1) and eta(+) proportional to nu(-1.8 +/- 0.2), consistent with Arecibo results and the theoretical expectations of eta proportional to nu(-2). From the arc curvature, we infer the scattering screen to be located at 0.20 +/- 0.02 kpc from the Earth, close to what was measured by RadioAstron at 324 MHz. From B1842+14, we find two scintillation arcs for the first time. The arcs' curvatures imply that they are caused by two scattering screens located at a distance of 0.3 +/- 0.2 kpc and 1.6 +/- 0.6 kpc from the Earth, respectively. The screen distance uncertainties mainly come from the uncertainty in pulsar's dispersion measure (DM)-derived distance. We present these FAST scintillation observations and discuss the future prospect of FAST pulsar scintillation study.