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Throughout the lifetime of WFC3 comma a growing number of blobs (small comma circular regions with slightly decreased sensitivity) have appeared in WFC3-IR images. Dark-Earth flats (observations of the dark side of the Earth) can be used to monitor the number and positions of blobs that appear in IR images due to dust on the channel select mechanism (CSM). These flats provide a high enough background level due to the dark-Earth airglow (virgul1000 DN - virgul3500 DN per pixel in each virgul25 second SPARS25 sample for F153M) which make the blobs easier to detect. By limiting the exposure time to 102.9 seconds comma we avoid saturating the detector and yet will obtain several 25-sec samples to select from comma in case some are contaminated by city lights. In addition to monitoring the number and positions of these blobs on the IR detector comma this program will allow us to monitor the repeatability of WFC3.s channel select mechanism movements to ensure it does not exhibit anomalous behavior. More information can be found in WFC3 ISR 2018-06. In addition comma observations are critical for evaluating and updating the WFC3-IR blob convolutional neural network comma which identifies new blobs (see WFC3 ISR 2021-08).在宽视场相机3（WFC3）的运行全生命周期中，WFC3红外（WFC3-IR）图像内出现的暗斑（blob，即灵敏度略有降低的小型圆形区域）数量持续攀升。暗地球平场（Dark-Earth flats）——即对地球暗侧的观测——可用于监测因通道选择机构（Channel Select Mechanism, CSM）上的尘埃而在红外图像中形成的暗斑的数量与位置。这类平场凭借暗地球气辉可提供足够高的背景电平：针对F153M滤光片的SPARS25采样模式，每个25秒采样的单像素信号范围为1000 DN至3500 DN，这使得暗斑的检测更为简便。通过将曝光时长限定为102.9秒，我们既能够避免探测器饱和，又可获取多组25秒采样样本以供筛选，以防部分样本受到城市灯光污染。除了监测红外探测器上这类暗斑的数量与位置外，本项目还可用于追踪WFC3的通道选择机构运动的重复性，以确保其不会出现异常行为。更多详细信息可参考WFC3仪器科学报告2018-06（WFC3 ISR 2018-06）。此外，相关观测对于评估并更新WFC3-IR暗斑卷积神经网络（Convolutional Neural Network）至关重要，该网络可用于识别新出现的暗斑（详见WFC3 ISR 2021-08）。