标题： L-BASS：一项生产1.4 GHz天图的绝对校准项目，I -- 科学背景和系统概述 显示英文标题

标题： L-BASS: a project to produce an absolutely calibrated 1.4 GHz sky map, I -- Scientific rationale and system overview

摘要： L-BASS 是一种旨在以 21 厘米（L 波段）的波长产生天空绝对校准地图的仪器，辐射测量精度小于或等于 0.1 K，并且角分辨率达到 23 度。 主要动机是改进更高分辨率地图的温度校准，并调查 ARCADE 2 团队提出的陡谱射电背景。 该仪器由一对可以独立扫描仰角的圆锥形喇叭天线组成；每个天线产生一个圆极化输出。 通过连接到数字光谱仪的连续比较接收器测量来自天线的信号差异，该光谱仪采样从 1400 MHz 到 1425 MHz 的信号，该频率范围位于受保护的射电天文频带内。 我们描述了项目的天体物理学动机、设计要求以及如何实现这些目标。 显示英文摘要

摘要： L-BASS is an instrument designed to produce an absolutely calibrated map of the sky at a wavelength of 21 cm (L-band) with a radiometric accuracy of less than or equal to 0.1 K and with an angular resolution of 23 degrees. The prime motivations are to improve the temperature calibration of higher resolution maps and to investigate the steep spectrum radio background proposed by the ARCADE 2 team. The instrument consists of a pair of conical horn antennas which can scan independently in elevation; each antenna produces a circularly polarized output. The difference in signals from the antennas is measured with a continuous-comparison receiver connected to a digital spectrometer sampling the signal from 1400 MHz to 1425 MHz within the protected radio astronomy band. We describe the astrophysical motivation for the project, the design requirements and how these will be attained.