Misalignment Considerations. Three kinds of sensor misalignment are possible. A separation misalignment is an error in the angular separation such that 0 = 0O + AO. For this type of error, both Eqs. (7-1) and (7-2) hold by simply replacing 0o with 90+ AO.
An elevation misalignment occurs when PF-1 is not parallel to the spacecraft spin axis but rather makes an angle, c, with the spin axis, as shown in Fig. 7-2. Note that the great circle SB no longer passes through A but rather makes an angle c with great circle AB. 0o is still the angle between the two PF sensors; therefore SC makes an angle 0o+t with AC. The arc length, </>, between B and D is the angular shift of the Sun-sighting events due to the elevation misalignment, «. By applying relation (7-1) to the two spherical triangles SDB and SDC, we obtain tan& =
FOV OF PF-2 AT SUN SNSHTINe 2
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