The detection of mJy/sub-mJy point sources is a significant challenge for single-dish radio telescopes. Detection or upper limits on the faint afterglow from GRBs or other sources at cosmological distances are important means of constraining the source modeling. Using the Sardinia Radio Telescope (SRT), we compare the sensitivity and robustness of three methods applied to the detection of faint radio sources from raster maps around a known source position: the smart ‘quick-look’ method, the ‘source extraction’ method (typical of high-energy astronomy), and the fit with a 2-D Gaussian. We developed a Python code specific for the analysis of point-like radio sources applied to the SRT C-band (6.9 GHz) observations of both undetected sources (GRB afterglows of 181201A and 190114C) and the detected Galactic X-ray binary GRS 1915 + 105. Our comparative analysis of the different detection methods made extensive use of simulations as a useful complement to actual radio observations. The best method for the SRT data analysis is the fit with a 2-D Gaussian, as it pushes down the sensitivity limits of single-dish observations – with respect to more traditional techniques – to ∼ 1.8 $\sim 1.8$ mJy, improving by ∼ 40 $\sim 40$ % compared with the initial value. This analysis shows that – especially for faint sources – good maps of the scanned region pre- or post-outburst are essential.

中文翻译：

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单天线射电望远镜弱射源检测分析方法

mJy/sub-mJy 点源的检测是单碟射电望远镜面临的重大挑战。在宇宙学距离上对来自 GRB 或其他源的微弱余辉的检测或上限是约束源建模的重要手段。使用撒丁岛射电望远镜 (SRT)，我们比较了用于从已知源位置周围的光栅图中检测微弱射源的三种方法的灵敏度和稳健性：智能“快速查看”方法、“源提取”方法（典型的高能天文学），并与二维高斯拟合。我们开发了一个 Python 代码，专门用于分析应用于 SRT C 波段 (6.9 GHz) 观测的点状射电源，未检测到的源（181201A 和 190114C 的 GRB 余辉）和检测到的银河 X 射线二进制 GRS 1915 + 105. 我们对不同检测方法的比较分析广泛使用模拟作为对实际无线电观测的有用补充。SRT 数据分析的最佳方法是与 2-D 高斯拟合，因为它将单盘观察的灵敏度限制 - 相对于更传统的技术 - 降低到 ~ 1.8 $\sim 1.8 $ mJy，提高了∼ 40 $\sim 40$ % 与初始值相比。该分析表明——特别是对于微弱的源——在爆发前或爆发后的扫描区域的良好地图是必不可少的。因为它将单盘观察的灵敏度限制 - 相对于更传统的技术 - 降低到 ~ 1.8 $\sim 1.8 $ mJy，与初始值相比提高 ~ 40 $\sim 40 $ %。该分析表明——特别是对于微弱的源——在爆发前或爆发后的扫描区域的良好地图是必不可少的。因为它将单盘观察的灵敏度限制 - 相对于更传统的技术 - 降低到 ~ 1.8 $\sim 1.8 $ mJy，与初始值相比提高 ~ 40 $\sim 40 $ %。该分析表明——特别是对于微弱的源——在爆发前或爆发后的扫描区域的良好地图是必不可少的。