LOFAR十米波巡天（LoDeSS）I. 巡天描述与首次数据发布
The LOFAR Decametre Sky Survey (LoDeSS) I. Survey description and first data release
- ASTRON, Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）
- Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）
- INAF – Istituto di Radioastronomia（意大利国家天体物理研究所射电天文研究所）
- Hamburger Sternwarte, Universität Hamburg（汉堡大学汉堡天文台）
- Leiden Observatory, Leiden University（莱顿大学莱顿天文台）
- Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·范·帕内库克天文研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文介绍LOFAR十米波巡天（LoDeSS）的首次数据发布，覆盖北天15-30 MHz频段，实现约45角秒分辨率和11.5 mJy束⁻¹噪声水平，为低频射电研究提供新机遇。
AI中文摘要：
十米波射电天空（约10-30 MHz）由于强烈的电离层失真和严重的射频干扰，在很大程度上仍未被探索。尽管其具有科学潜力，包括探测来自老化电子群的陡谱同步辐射以及行星和恒星磁层的相干射电辐射，但在这些频率下的亚角分成像直到最近才通过诸如低频阵列（LOFAR）等仪器成为可能。在这项工作中，我们介绍了LOFAR十米波巡天（LoDeSS）的首次数据发布（DR1），该巡天绘制了赤纬20°以上、频率在15至30 MHz之间的北天图。LoDeSS达到了约45角秒的角分辨率，在23 MHz的中心频率下典型噪声水平约为11.5 mJy束⁻¹。观测使用LOFAR低频天线（LBA）系统，采用多波束策略，每个指向的典型积分时间约为5小时。观测在夜间进行，以减少电离层反射的射频干扰的影响。由于电离层条件和因射频干扰而标记的数据比例不同，各天区的数据质量有所差异。本次首次发布覆盖了完整巡天面积的约15%，由最初围绕系外行星候选体为射电极光发射而选择的场组成。向社区发布的产品包括斯托克斯I和V的主波束校正图像，以及具有可靠通量密度标度的天区的源星表。此次发布表明，LOFAR能够在十米波波段实现具有空前分辨率的高灵敏度、大视场成像，为脉冲星、系外行星系统、星系团及其他低频现象的研究开辟了新的机遇。
英文摘要：
The decametre radio sky ($\sim 10$-$30$ MHz) remains largely unexplored due to strong ionospheric distortions and severe radio-frequency interference. Despite its scientific potential, including access to steep-spectrum synchrotron emission from aged electron populations and coherent radio emission from planetary and stellar magnetospheres, sub-arcminute imaging at these frequencies has only recently become feasible with instruments such as the Low Frequency Array (LOFAR). In this work, we present the first data release (DR1) of the LOFAR decametre Sky Survey (LoDeSS), which maps the northern sky above a declination of $20^\circ$ between 15 and 30 MHz. LoDeSS reaches an angular resolution of $\sim45^{\prime\prime}$ and typical noise levels of $\sim11.5$ mJy beam$^{-1}$ at a central frequency of 23 MHz. Observations were obtained with the LOFAR Low Band Antenna (LBA) system using a multi-beam strategy, with typical integration times of $\sim5$ h per pointing. They were carried out at night to reduce the impact of ionospherically reflected radio-frequency interference. Data quality varies across fields as a result of the ionospheric conditions and the fraction of data flagged due to radio-frequency interference. This first release covers $\sim15\%$ of the full survey area and consists of fields originally selected around exoplanet candidates for radio auroral emission. The products released to the community include primary-beam-corrected images in Stokes I and V, and a source catalogue for fields with reliable flux density scales. This release demonstrates that LOFAR enables sensitive, wide-field imaging in the decametre regime with unprecedented resolution, opening new opportunities for studies of pulsars, exoplanetary systems, galaxy clusters, and other low-frequency phenomena.
