An External Calibrator for HI Observatories

HI 天文台的外部校准器

• 批准号: 1407646
• 负责人: Judd Bowman
• 金额: $ 6.9万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-15 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1407646&HistoricalAwards=false
• 关键词: External; Calibrator; HI; Observatories

An exciting and scientifically important frontier of modern astronomy is the push to understand the Epoch of Reionization (EoR), a time in the distant past when the first stars began to influence the material between galaxies. This era is also referred to as "Cosmic Dawn", and has been identified as potentially rife with new discoveries and one of the key problems to be understood in the near future. With that in mind, some innovative instrumentation has been under development, including new radio-astronomy arrays suchs as the Murchison Widefield Array (MWA) and the Precision Array for Probing the Epoch of Reionization (PAPER). The precise extraction of the needed information from such instruments requires unusual measures for instrument calibration, and this proposal addresses that need by building ECHO, a helicopter drone to carry a test transmitter over the telescope array and investigate its actual spatial response pattern to a very high precision.A key obstacle to extracting the information on astrophysical processes from data measured by the new generation of telescope arrays is the accurate removal of foreground emission due to extraneous sources unrelated to the EoR emission being sought. That foreground emission problem depends critically on an accurate knowledge of the as-built primary beam of each telescope in the array. Current techniques, such as beam modeling, are uncertain at the 20% level; this project intends to push that limit down to 1% for MWA and PAPER. The scientific payoff is potentially very large.The ECHO project will recruit and train undergraduates interested in electronics and field experiments, and will feature strong student involvement in many phases of design, construction, and testing.Funding for this project is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.

现代天文学的一个令人兴奋且具有重要科学意义的前沿领域是推动对再电离时代（EoR）的理解，这是在遥远的过去第一批恒星开始影响星系之间物质的时期。 这个时代也被称为“宇宙黎明”，并被认为可能充满新发现，也是不久的将来需要理解的关键问题之一。 考虑到这一点，一些创新仪器正在开发中，包括新的射电天文阵列，例如默奇森宽场阵列（MWA）和探测再电离时代的精密阵列（PAPER）。 从此类仪器中精确提取所需信息需要采取非常规的仪器校准措施，本提案通过建造 ECHO 来满足这一需求，ECHO 是一架直升机无人机，可在望远镜阵列上携带测试发射器，并研究其实际空间响应模式，以达到非常高的水平。从新一代望远镜阵列测量的数据中提取天体物理过程信息的一个主要障碍是准确去除由于与所寻求的 EoR 发射无关的外部源而产生的前景发射。 前景发射问题主要取决于对阵列中每个望远镜的建成主光束的准确了解。 当前的技术（例如梁建模）的不确定性为 20%；该项目打算将 MWA 和 PAPER 的限制降低至 1%。 科学回报可能非常巨大。ECHO 项目将招募和培训对电子和现场实验感兴趣的本科生，并将让学生积极参与设计、构建和测试的许多阶段。该项目的资金由 NSF 部门提供天文科学通过其先进技术和仪器计划。