We employ the in-site automated observation radiometric calibration (AORC) approach to perform vicarious calibration, which does not require the manual efforts of a field team to measure the surface conditions. By using an automated test-site radiometer (ATR), the surface radiance at any moment in time can be obtained. This Letter describes the AORC approach and makes use of data to compute top-of-atmosphere radiance and compare it to measurements from the Moderate Resolution Imaging Spectroradiometer. The result shows that the relative deviation is less than 5% and the uncertainty is less than 6.2%, which indicates that the in-site AORC maintains an accuracy level on par with traditional calibration.