<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def rotateInDeclination(v1, theta_deg):
 """Rotation is chosen so a rotation of 90 degrees from zenith ends up at ra=0, dec=0"""

    axis = np.array([0,-1,0])
    return rotateAroundVector(v1, axis, theta_deg)