1+_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] CRAWFORD FLETCHER  ]    PASS PROGRAM NOTE        ]       107352     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:            ]
 ] LSIS/(713) 282-7333]      RELEASE NOTE( )        ]       06/15/94   ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI-22 AND SUBS                ]  CREW ( )  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )]  G2 AND G8                      ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: FCS AND D/L                                      ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: 4.35                                           ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ]         ARCSIN GPC ERROR IN AUTO_MNVR_TRACK                         ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]    ONE OR MORE GPC ERRORS COULD OCCUR IN THE ORBIT DAP PROCESSING IN]
 ] THE AUTO_MNVR_TRACK MODULE.  THESE ERRORS OCCUR IN ATTEMPTING TO    ]
 ] TAKE THE ARCSINE OF THE MAGNITUDE OF A VECTOR (WITH MAGNITUDE       ]
 ] GREATER THAN ONE) THAT REPRESENTS THE AXIS OF ROTATION THAT IS      ]
 ] DERIVED FROM THE PRODUCT OF TWO QUATERNIONS: ONE QUATERNION         ]
 ] REPRESENTS THE DESIRED BODY ATTITUDE AND THE OTHER REPRESENTS THE   ]
 ] CURRENT BODY ATTITUDE.  WHENEVER THE TWO QUATERNIONS ARE APPROXI-   ]
 ] MATELY 180 DEGREES APART AND AT LEAST ONE OF THE QUATERNIONS IS NOT ]
 ] NORMALIZED, THE PRODUCT QUATERNION THAT RESULTS HAS A SCALAR THAT IS]
 ] APPROXIMATELY ZERO AND A VECTOR PART WITH A MAGNITUDE THAT IS MOST  ]
 ] LIKELY GREATER THAN ONE.  IT IS THE ATTEMPT TO TAKE THE ARCSINE OF  ]
 ] A QUANTITY THAT IS GREATER THAN ONE THAT RESULTS IN THE GPC ERROR.  ]
 ]                                                                     ]
 ]                  (CONTINUED ON SUPPLEMENTAL SHEET)                  ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]                                                                     ]
 ] SHOULD THE GPC ERRORS PERSIST FOR MORE THAN ONE MINUTE, IT IS       ]
 ] RECOMMENDED THAT THE CREW SELECT PRIMARY JETS.                      ]
 ]                                                                     ]
 ] A STANDARD RETURN IS MADE IN THE RUN TIME LIBRARY ROUTINE AS        ]
 ] FOLLOWS:                                                            ]
 ]      ARCSIN(X) = SIGN(X) PI/2, FOR ]X] > 1                          ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]LSIS:  HUGH D. STOVALL    DATE 08/02/94]                             ]
 ]     -------------------      ---------]                             ]
 ]FDSD:ELIZABETH A.FOUNTAIN DATE 08/02/94]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 08/03/94 ]
 ]PF MGR:  K. L. LINDSAY    DATE 08/03/94]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
 @



 +_____________________________________________________________________
 ]                                                                     ]
 ]                       SUPPLEMENTAL SHEET                            ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] AUTHOR:            ]                             ] DR:              ]
 ] CRAWFORD FLETCHER  ]    PASS PROGRAM NOTE        ]       107352     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:            ]
 ] LSIS/(713) 282-7333]      RELEASE NOTE ( )       ]       06/15/94   ]
 ]____________________]_____________________________]__________________]
 ] TITLE:                                                              ]
 ]        ARCSIN GPC ERROR IN AUTO_MNVR_TRACK                          ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ] FOR THIS ERROR: GROUP=4, CODE=10, AND PDE=GEI_ORBIT_HFE.  SUCH      ]
 ]  ERRORS ARE LIKELY TO OCCUR ONLY AT ORBITER ROTATIONAL RATES        ]
 ]  GREATER THAN 5 DEGREES/SECOND AND 'AUTO' MODE SELECTED WITH SMALL  ]
 ]  CONTROL AUTHORITY, I. E., VERNIER JETS OR ALT MODE WITH LONG       ]
 ]  DELAYS.                                                            ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 @
