Interstellar interferometry: precise curvature measurement from pulsar secondary spectra

ABSTRACT The parabolic structure of the secondary or conjugate spectra pulsars is often result isolated one-dimensional (or at least highly anisotropic) lenses in interstellar medium (ISM). curvature these features contains information about velocities Earth, ISM, and pulsar along primary axis lens. As a result, measuring variations over course year, orbital period for binaries, can constrain properties screen pulsar. In particular, distance inclination binary systems be found multiple screens with prior on sin(i). By mapping into space where main arc inverted arclets are straight lines, we able to make use full content from arclet curvatures, amplitudes, phases using eigenvectors uniquely optimally retrieve phase information. This allows higher precision measurement than standard Hough transform available. Our technique also directly yields best-fitting impulse response function lens given terms Doppler shift, time delay, magnification images sky as seen single observatory. extended holographic imaging by combining telescopes. We present examples this new method both simulated data actual observations PSR B0834+06.