The Cadmium–Zinc–Telluride (CZT) Imager on board AstroSat is a hard X-ray imaging spectrometer operating in the energy range of 20–100 keV. It also acts as an open hard X-ray monitor above 100 keV capable of detecting transient events like the Gamma-ray Bursts (GRBs). Additionally, the instrument has the sensitivity to measure hard X-ray polarization in the energy range of 100–400 keV for bright on-axis sources like Crab and Cygnus X-1 and bright GRBs. As hard X-ray instruments like CZTI are sensitive to cosmic rays in addition to X-rays, it is required to identify and remove particle induced or other noise events and select events for scientific analysis of the data. The present CZTI data analysis pipeline includes algorithms for such event selection, but they have certain limitations. They were primarily designed for the analysis of data from persistent X-ray sources where the source flux is much less than the background and thus are not best suited for sources like GRBs. Here, we re-examine the characteristics of noise events in CZTI and present a generalized event selection method that caters to the analysis of data for all types of sources. The efficacy of the new method is reviewed by examining the Poissonian behavior of the selected events and the signal to noise ratio for GRBs.

AstroSat 上的镉-锌-碲化物 (CZT) 成像仪是一种硬 X 射线成像光谱仪，在 20-100 keV 的能量范围内运行。它还充当 100 keV 以上的开放式硬 X 射线监视器，能够检测伽马射线暴 (GRB) 等瞬态事件。此外，该仪器具有测量 100-400 keV 能量范围内硬 X 射线偏振的灵敏度，用于明亮的同轴源，如蟹和天鹅座 X-1 以及明亮的 GRB。由于CZTI等硬X射线仪器除X射线外还对宇宙射线敏感，因此需要识别和去除粒子诱发或其他噪声事件，并选择事件进行数据科学分析。目前的 CZTI 数据分析管道包括用于此类事件选择的算法，但它们具有一定的局限性。它们主要用于分析来自持久性 X 射线源的数据，其中源通量远小于背景，因此不太适合像 GRB 这样的源。在这里，我们重新检查了 CZTI 中噪声事件的特征，并提出了一种通用的事件选择方法，可以满足所有类型源的数据分析。通过检查所选事件的泊松行为和 GRB 的信噪比来评估新方法的有效性。