THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
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DOI：
10.1088/2041-8205/808/1/l1
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发表时间：
2015-07-20
影响因子：
7.9
通讯作者：
Wood, S. J.
中科院分区：
文献类型：
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作者：
Fomalont, E. B.;Vlahakis, C.;Wood, S. J.
阿塔卡马大毫米/亚毫米阵列(ALMA)的一个主要目标是以几十毫角秒的分辨率拍摄准确的图像，这在亚毫米(亚毫米)波长上需要高达15公里的基线。为了开发和测试这一能力，从2014年9月至11月下旬进行了一次长期基线运动(LBC)，最终对选定的科学核查(SV)目标进行了端到端的观测、校准和成像。本文概述了这项运动及其主要结果，包括对ALMA站点长基线的短期相干性和系统相位误差的调查，对SV目标和观测的总结，以及对长基线科学观测策略的建议。类星体3C 138在97 GHz和241 GHz的深度ALMA图像也与VLA 43 GHz的结果进行了比较，表明在几个百分点的水平上是一致的。由于广泛的LBC测试计划，在长基线上非常成功的SV成像在类似350 GHz的情况下获得了高达19 mA的角分辨率。利用ALMA在长达15公里的基线上进行观测现在是可能的，并为亚毫米天文学开辟了新的参数空间。
A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to similar to 15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at similar to 350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.