Since 2004 we have been carrying out a pulsar survey of the Cygnus region with the Westerbork Synthesis Radio Telescope (WSRT) at a frequency of 328 MHz. The survey pioneered a novel interferometric observing mode, termed 8gr8 (eight-grate), whereby multiple simultaneous digital beams provide high sensitivity over a large field of view. Since the Cygnus region is known to contain OB associations, it is likely that pulsars are formed here. Simulations have shown that this survey could detect 70 pulsars, which would increase our understanding of the radio pulsar population in this region. We also aim to expand the known population of intermittent and rotating radio transient (RRAT)-like pulsars. In this paper we describe our methods of observation, processing and data analysis, and we present the first results. Our observing method exploits the way a regularly spaced, linear array of telescopes yields a corresponding regularly spaced series of so-called ``grating'' beams on the sky. By simultaneously forming a modest number (eight) of offset digital beams, we can utilize the entire field of view of each WSRT dish, but retain the coherently summed sensitivity of the entire array. For the processing we performed a large number of trial combinations of period and dispersion measure (DM) using a computer cluster. In the first processing cycle of the WSRT 8gr8 Cygnus Survey, we have discovered three radio pulsars, with spin periods of 1.657, 1.099 and 0.445 seconds. These pulsars have been observed on a regular basis since their discovery, both in a special follow-up programme as well as in the regular timing programme. The timing solutions are presented in this paper. We also discuss this survey method in the context of the SKA and its pathfinders.
Timing of young radio pulsars I: Timing noise, periodic modulation and proper motion
年轻恒星的平稳降旋受到两种非确定性现象的扰动：毛刺和定时噪声。虽然定时噪声提供了对极端密度下的核物理和等离子体物理的见解，但它是高精度脉冲星定时实验的障碍。本文提出了一种改进的基于贝叶斯推理的方法，用于同时模拟用64 m Parkes射电望远镜观测了$\sim$ 10年的85个高$\dot{E}$射电望远镜样本的随机和确定性参数。定时噪声是一个红色的过程，我们开发了一个参数化的基础上的红色噪声幅度（$A_{\rm red}$）和频谱指数（$β$）。我们测量的中位数$A_{\rm red}$为$-10.4^{+1.8}_{-1.7}$ yr $^{3/2}$和$β$为$-5.2^{+3.0}_{-3.8}$，并表明定时噪声的强度与$ν^{1}|\dotν|^{-0.6\pm0.1}$成正比，其中$ν$是脉冲星的自旋频率，$\dotν$是其自旋下降率。最后，我们测量了19颗恒星的重要制动指数，两颗恒星的自行，并讨论了五颗恒星到达时间的周期性调制。
Why Gravitational Wave Science Needs Pulsar Timing Arrays And Why Pulsar Timing Arrays Need Both Arecibo and the GBT: A Response to the NSF-AST Portfolio Review from the NANOGrav Collaboration
