using gradiometric principles, e.g. [@Ness1971] and comparison with scalar magnitude instruments, e.g. [@Olsen2003; @Primdahl2006]. Additionally solar wind electron beams, sensitive to the mean field direction, can be used in calibrating fluxgate offsets [@Plaschke2014; @Connerney2015].

For PSP, the attitude and pointing requirements of the spacecraft preclude the use of controlled maneuvers during perihelion, spacecraft rolls (both sun-pointed and conical rotations) are thus performed before and after each perihelion encounter to establish zero levels of the spacecraft magnetic field. In between such controlled rotations, measurements of Alfvénic rotations of the solar wind magnetic field have been implemented to track variations in the spacecraft field, allowing for an estimate of zero levels during each perihelion encounter, when controlled maneuvers cannot be performed [@Leinweber2008]. Figure \[fig:rolls\] shows the offsets for MAGo over the first encounter computed using both spacecraft rolls, and higher rate estimations from Alfvénic rotations. Spacecraft housekeeping and engineering data are currently under analysis in order to model the effects of variations in the solar panel array, which change orientation over the course of the orbit, on the measured DC offsets. Gradiometric techniques are in development to further verify and monitor offset drifts during each perihelion encounter. In addition to the removal 