| CPC E21B 47/01 (2013.01) [E21B 47/024 (2013.01)] | 18 Claims |

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1. A method for performing a downhole survey, comprising:
rotating a downhole tool;
stabilizing a survey package relative to the rotating downhole tool;
receiving gyroscopic measurements from the survey package, wherein the gyroscopic measurements include x-axis gyroscopic measurements, y-axis gyroscopic measurements, and z-axis gyroscopic measurements;
receiving accelerometer measurements from the survey package;
while rotating the downhole tool, determining a y-axis earth rate rotational component in a direction corresponding to a y-axis of the downhole tool from the y-axis gyroscopic measurements, the z-axis gyroscopic measurements, and a toolface angle of the downhole tool;
while rotating the downhole tool, determining an x-axis earth rate rotational component in a direction corresponding to an x-axis of the downhole tool from the x-axis gyroscopic measurements and the toolface angle of the downhole tool;
based on the y-axis earth rate rotational component and the x-axis earth rate rotational component, determining a tool azimuth of the downhole tool while the downhole tool is rotating; and
adjusting a trajectory of the downhole tool using the tool azimuth.
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