# Intra-Day Variability Observations of Two Dozens of Blazars at 4.8 GHz
## 4 Summary  
We present the first results of the IDV observations of about two dozens of blazars with Urumqi 25 m radio telescope in 8-12 February 2014 and 7-9 March. Most of target sources are selected in parallel from the observing list of RadioAstron AGN monitoring campaign. The majority of the blazars exhibit IDV with a high confidence level, some of them show prominent IDVs in the two sessions. Seven new IDV sources are detected in our observations.  
We find that the three strongest IDVs appear in relatively lower flux density \(<S>\)\(<\) 0.7 Jy in the sample, in which blazar 1357 + 769 is discovered as strong IDV for the first time. No significant correlation between the IDV strength and either redshift or Galactic latitude is found from this blazar sample.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Pearson** & \(P_{null}\) & **Spearman** & \(P_{null}\) \\
**1** & **2** & **3** & **4** & **5** \\ \hline \multicolumn{5}{c}{**Modified modulation index (\(m^{\prime}\)) versus redshift (z)**} \\ Full & \(-\)0.121 & 0.475 & \(-\)0.005 & 0.978 \\ S1 & \(-\)0.173 & 0.465 & \(-\)0.242 & 0.305 \\ S2 & \(-\)0.032 & 0.903 & 0.279 & 0.277 \\ \hline \multicolumn{5}{c}{**Modified modulation index (\(m^{\prime}\)) versus Galactic latitude**} \\ Full & 0.016 & 0.926 & \(-\)0.128 & 0.449 \\ S1 & \(-\)0.045 & 0.850 & \(-\)0.122 & 0.607 \\ S2 & \(-\)0.038 & 0.886 & \(-\)0.272 & 0.290 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Results of correlation analysis for modified modulation index (\(m^{\prime}\)), redshift (\(z\)) and Galactic latitude. Column 1: Sample (Full—all target sources in Tables 1 and 2; S1—target sources in Table 1; S2—target sources in Table 2). Column 2 and 3: Pearson correlation coefficient and the probability of no correlation. Column 4 and 5: Spearman correlation coefficient and the probability of no correlation.  
**Author Contributions:** Conceptualization, writing--original draft, X.L.; analysis and plotting, X.W., N.C.; and review and editing, J.L., L.C., X.Y. and T.P.K. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work is supported by the National Key R&D Program of China under grant No. 2018 YEA0404602, and partly supported by [PERSON]'s Xinjiang Tianchi Bairen project and CAS Pioneer Hundred Talents Program, and the CAS 'Light of West China' Program under grant No. 2018-XBQNNXZ-B-021 and the NSFC under grant No. U2031212 and 61931002. L.C. is also supported by the Youth Innovation Promotion Association of the CAS under grant No. 2017084.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** We thank the referees for their helpful comments. This work is based on observations made with the Urumqi 25 m radio Telescope, which is operated by the Key Laboratory of Radio Astronomy, Chinese Academy of Sciences. The NASA/IPAC Extragalactic Database (NED) is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology.  
**Conflicts of Interest:** The authors declare no conflict of interest.