论文标题
UGMRT在频段4中的极化惯例
The Polarization Convention of the uGMRT in Band 4
论文作者
论文摘要
我们提出了一项实验，以了解升级的巨型Metrewave射电望远镜（UGMRT）的频段4（550--900 MHz）采用的极化惯例。为此，我们在该乐队中观察到Pulsar B1702--19，无论是在干涉测量和PULSAR模式中，并将结果与已知的Stokes $ i $，$ Q $，$ u $，$ u $，$ v $ profiles与Lovell telescope获得的比较。我们发现，从UGMRT的干涉法和脉冲星模式获得的结果彼此一致。但是，尽管通过Lovell望远镜获得的UGMRT匹配获得了Stokes $ u $ profile，但Stokes $ Q $和$ v $却没有。如果在该乐队中的$ x $和$ y $偶极子（从中衍生出$ r $和$ l $）被换成W.R.T. IAU公约。根据IEEE公约，交换使UGMRT乐队4的$ rr^*$和$ ll^*$分别为$ ll^*$和$ rr^*$。这意味着，如果我们需要比较UGMRT乐队4获得的两极分化测量值与诸如Lovell，Parkes，非常大的阵列等的望远镜（所有这些都遵循IEEE遵循IEEE的大会，以定义左手和左手的圆形极化），我们必须互换$ rr^*$ rr^*$ and $ ll^*$，并更改Stokes $ Q $ Q $ q $ Q $ Q $ Q $ for for for ugmrt Data。请注意，这是UGMRT频段4的当前惯例，一旦完成偶极子的交换，将来很可能会改变。完成后，它将在另一份技术报告中通知。
We present an experiment performed to understand the polarization convention adopted for band 4 (550--900 MHz) of the upgraded Giant Metrewave Radio Telescope (uGMRT). For that we observed the pulsar B1702--19 in this band, both in interferometry and pulsar modes, and compare the results with its already known Stokes $I$, $Q$, $U$, $V$ profiles obtained with the Lovell telescope. We find that the results obtained from interferometry and pulsar modes of the uGMRT agree with each other. However, although the Stokes $U$ profile obtained with the uGMRT match with that obtained by the Lovell telescope, Stokes $Q$ and $V$ do not. This can be explained if the $X$ and $Y$ dipoles in this band, from which $R$ and $L$ are derived, are swapped w.r.t. the IAU convention. The swapping makes $RR^*$ and $LL^*$ of the uGMRT band 4 to be $LL^*$ and $RR^*$ respectively according to the IEEE convention. This implies that if we need to compare polarization measurements obtained in band 4 of the uGMRT with telescopes like Lovell, Parkes, Very Large Array etc. (all follow IEEE convention for defining right and left hand circular polarization), we must interchange $RR^*$ and $LL^*$, and change the sign of Stokes $Q$ for the uGMRT data. Note that this is the current convention for uGMRT band 4, and is likely to change in future once the swapping of the dipoles is taken care of. Once it is done, it will be notified in another technical report.
