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文摘
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为了在云南天文台40 m天线上开展射电天文研究,使用它进行了河外射电源流量试观测。通过对河外致密源进行ON/OFF跟踪观测,得到射电源的流量变化曲线。但数据质量并不理想,说明系统存在一些问题。随后,根据对该望远镜系统的稳定性及其无线电环境干扰现状的考察,以及对现存问题的分析,提出了相应的解决方法。 |
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其他语种文摘
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To open new opportunities on radio astronomical research with the recently constructed YNAO 40 m radio telescope,we carried out test observations of extragalactic radio sources.Three compact radio sources(3C273,3C295,and 0716+714) were observed with the ON/OFF mode.In such a mode the telescope was pointed first toward the source and then 2 degrees off the source.In each cycle there are 2 minutes on-source observation and 2 minutes off-source observation.The observational wavelength bands were alternated between the S and X bands but with short time intervals.We present here the S-and X-band flux-density curves of the three sources.There are unexpected drifts on various time scales in these curves.The sensitivity limits of the observations are about 1 Jy.Through the observation,we have identified problems of the telescope stability and environmental radio-frequency interference.By pointing the telescope to the Zenith without tracking,we found ≤1% per hour drifts in the flux-density curve,which are much less than the drifts observed in an ON/OFF mode for a source.In the S band,there is a strong interference signal at the frequency 2 142 MHz.This interference signal has several harmonics,so that it polluted our data severely.The frequency interference in the X band is weaker than in the S band.We finally propose measures to improve the telescope capacity.These include developing of a counter-interference system,using a radiometer for measuring the K factor to eliminate gain drifts of devices,and performing drift-scan observation without telescope tracking to avoid other unstable factors. |
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来源
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天文研究与技术
,2012,9(1):7-13 【扩展库】
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关键词
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射电天文
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天线
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流量观测
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无线电干扰
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地址
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1.
中国科学院国家天文台, 中国科学院射电天文重点实验室, 云南, 昆明, 100012
2.
中国科学院国家天文台云南天文台, 云南, 昆明, 650011
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语种
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中文 |
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文献类型
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研究性论文 |
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ISSN
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1672-7673 |
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学科
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天文学 |
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基金
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国家973计划
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文献收藏号
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CSCD:4442151
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