Parkes observations for project P1129 semester 2022OCTS_06

PSR J0837$-$2454 is a young, high-Galactic-latitude pulsar, whose distance derived from dispersion measure (DM) implies a height of $>$1~kpc above the Galactic plane. The young age (28kyr) and position can be explained if (i) the pulsar was born at this high Galactic $z$-height from a runaway or walkaway O/B star; or (ii) the DM-derived distance to this pulsar is incorrect and the pulsar is closer to the plane of the Galaxy. VLBA observations will provide us with an estimate of the proper motion of the pulsar, along with the distance to the pulsar through a measurement of the parallax if the pulsar is closer than the DM implies. These measurements are crucial to determining whether or not this pulsar represents the remnants of a rare Milky Way halo O/B star. This proposal seeks to continue monitoring this pulsar in order to maintain phase connection of the timing solution throughout the duration of planned VLBA observations. This is crucial for conducting gated observations with the VLBA, but will also contribute to studies of the pulsar's emission properties and the ISM along the line-of-sight to the pulsar.PSR J0837−2454是一颗年轻的高银纬脉冲星（pulsar），通过色散量（dispersion measure, DM）推导得到的距离显示，它位于银盘上方高度超过1千秒差距（kpc）的位置。该脉冲星的年轻年龄（28千年，kyr）与位置特征，可通过两种假说得到合理解释：其一，该脉冲星诞生于该高银面垂直高度处，源自一颗逃逸或超逃逸O/B型星；其二，基于色散量推导得到的该脉冲星距离存在误差，其实际位置更接近银盘平面。 甚长基线阵列（Very Long Baseline Array, VLBA）观测将为我们提供该脉冲星的自行（proper motion）估算结果；若该脉冲星的实际距离比色散量推导值更近，则还可通过视差（parallax）测量获取其精确距离。上述测量结果对于判断该脉冲星是否属于罕见的银晕O/B型星遗迹，具有关键意义。 本观测提案计划持续监测该脉冲星，以在预定的VLBA观测全程维持计时解（timing solution）的相位连续性。这一要求不仅是开展VLBA选通观测（gated observations）的必要前提，同时也将为该脉冲星的辐射特性研究，以及沿其视线方向的星际介质（Interstellar Medium, ISM）相关研究提供重要支撑。