论文标题
使用螃蟹星云作为韩国VLBI网络的极化角校准器
Using the Crab Nebula as Polarization Angle Calibrator for the Korean VLBI Network
论文作者
论文摘要
螃蟹星云被广泛用作单次无线电观测的极化角校准器，因为其亮度，高度的线性极化和众所周知的极化角度在宽频率范围内。但是，蟹状星云不能直接用作韩国VLBI网络（KVN）单次观察的极化角校准器，因为望远镜的梁尺寸小于星云的尺寸。为了确定KVN所见的蟹状星云的极化角，我们使用3C 286，这是一种紧凑的极化外层次射流源，其极化角是众所周知的，作为参考目标。我们在2017年至2021年之间观察了螃蟹星云和3C 286，发现了蟹状总强度峰值的极化角度（赤道坐标（J2000）R.A. $ = $ = $ = $ 05 $^{\ rm H} {\ rm H} 22$^\circ$00'44.0982") are $154.2^\circ \pm 0.3^\circ$, $151.0^\circ \pm 0.2^\circ$, $150.0^\circ \pm 1.0^\circ$, and $151.3^\circ \pm 1.1^\circ$ at 22, 43, 86, and 94 GHz, respectively. We also找到Pulsar位置的极化角度（ra $ = $ 05 $^{\ rm h} $ 34 $^{\ rm m} $ 31.971 $^{\ rm s} $和dec $ = $ = $ = $ 22 $^\ circe $ 00'52.06”） 0.4^\ circ $，$ 149.0^\ Circ \ PM 1.0^\ Circ $在22、43和86 GHz时为KVN。在129 GHz时，我们建议使用$ 149.0^\ Circ \ PM 1.6^\ Circ $以总强度峰值为$ 150.2^\ Circ \ PM \ PM 2.0^\ Circ $在PULSAR位置，该位置在毫米（IRAM）30米远程的PULSAR位置上获得了射线天文学研究所。基于我们的研究，螃蟹星云中的两个位置都可以用作KVN单次观测值的极化角校准器。
The Crab nebula is widely used as a polarization angle calibrator for single-dish radio observations because of its brightness, high degree of linear polarization, and well-known polarization angle over a wide frequency range. However, the Crab nebula cannot be directly used as a polarization angle calibrator for single-dish observations with the Korean VLBI Network (KVN), because the beam size of the telescopes is smaller than the size of the nebula. To determine the polarization angle of the Crab nebula as seen by KVN, we use 3C 286, a compact polarized extragalactic radio source whose polarization angle is well-known, as a reference target. We observed both the Crab nebula and 3C 286 with the KVN from 2017 to 2021 and find that the polarization angles at the total intensity peak of the Crab nebula (equatorial coordinates (J2000) R.A. $=$ 05$^{\rm h}$34$^{\rm m}$32.3804$^{\rm s}$ and Dec $=$ 22$^\circ$00'44.0982") are $154.2^\circ \pm 0.3^\circ$, $151.0^\circ \pm 0.2^\circ$, $150.0^\circ \pm 1.0^\circ$, and $151.3^\circ \pm 1.1^\circ$ at 22, 43, 86, and 94 GHz, respectively. We also find that the polarization angles at the pulsar position (RA $=$ 05$^{\rm h}$34$^{\rm m}$31.971$^{\rm s}$ and Dec $=$ 22$^\circ$00'52.06") are $154.4^\circ\pm 0.4^\circ$, $150.7^\circ\pm 0.4^\circ$, and $149.0^\circ\pm 1.0^\circ$ for the KVN at 22, 43, and 86 GHz. At 129 GHz, we suggest to use the values $149.0^\circ \pm 1.6^\circ$ at the total intensity peak and $150.2^\circ \pm 2.0^\circ$ at the pulsar position obtained with the Institute for Radio Astronomy in the Millimeter Range (IRAM) 30-meter Telescope. Based on our study, both positions within the Crab nebula can be used as polarization angle calibrators for the KVN single-dish observations.
