Parkes observations for project P1168 semester 2023APRS_01

We discovered seven pulsars in the globular cluster Terzan 1 with the Green Bank Telescope (GBT), the first pulsars to be found in this cluster. The discoveries include five fully-recycled millisecond pulsars (MSPs) with spin periods between 3 and 6 ms, an 11-ms MSP, and a pulsar with an unusually long spin period of 134 ms. Our preliminary timing suggested that all seven are likely isolated pulsars, consistent with Terzan 1 being a core-collapsed globular cluster. The 134-ms pulsar is an especially interesting discovery in the context of pulsar formation via electron-capture rather than core-collapse supernovae. We observed Terzan 1 at Parkes with the UWL receiver in 2022OCT to test whether the pulsars could be detected and thus timed at Parkes. All seven pulsars are significantly detected in both observations. We propose a year-long timing campaign with Parkes/UWL to obtain phase-connected timing solutions for these pulsars; we request continuing status to continue these timing observations through 2023OCT. To refine the timing parameters and probe the pulsars' acceleration in the cluster potential, we will extend phase connection beyond one year using the 2022OCT observations, and we will attempt to phase connect back to the original GBT discovery pointings. In addition to timing, we will probe the pulsars' polarization properties and the Galactic magnetic field in the direction of Terzan 1; and the proposed observations will also be searched for new pulsars that may have been missed in previous observations.本研究利用绿岸望远镜（Green Bank Telescope, GBT）在球状星团Terzan 1中发现了7颗脉冲星（pulsar），这是该星团内首次被发现的脉冲星。本次发现的脉冲星包括5颗自旋周期介于3至6毫秒的完全再循环毫秒脉冲星（millisecond pulsars, MSPs）、1颗11毫秒的毫秒脉冲星，以及1颗自旋周期达134毫秒的超长周期脉冲星。初步计时分析显示，这7颗脉冲星均为孤立脉冲星，这与Terzan 1属于核坍缩球状星团的结论一致。相较于通过核坍缩超新星（core-collapse supernovae）形成脉冲星的经典路径，这颗134毫秒脉冲星的发现尤为特殊，其形成机制或更符合电子俘获（electron-capture）过程的相关理论。为验证帕克斯望远镜（Parkes）能否探测到这批脉冲星并开展计时观测，我们于2022年10月利用UWL接收机（UWL receiver）对Terzan 1进行了观测。两次观测均显著探测到全部7颗脉冲星。我们计划依托帕克斯望远镜与UWL接收机开展为期一年的计时观测项目，以获取这批脉冲星的相位连接计时解（phase-connected timing solutions）；同时申请延长观测时长，将本次计时观测持续至2023年10月。为优化计时参数并探究脉冲星在星团引力场（cluster potential）中的加速度，我们将借助2022年10月的观测数据将相位连接时长延长至一年以上，同时尝试回溯至绿岸望远镜的原始发现指向完成相位连接。除计时观测外，本次研究还将分析这批脉冲星的偏振特性（polarization properties）与Terzan 1方向的银河系磁场（Galactic magnetic field）；此外，我们还将在本次观测数据中搜寻此前观测中可能遗漏的新脉冲星。