SUBJ: GPS STATUS 21 SEP 90
1. SATELLITES, PLANES AND CLOCKS (CS=CESIUM RB=RUBIDIUM):
SLOTS MAY NOT BE FINAL UNTIL AFTER 21-SATELLITE REPHASING
A. BLOCK I : PRNS  3,  6,  9, 11, 12, 13
   PLANE   : SLOT D1, A3, A2, C2, A1, C1
   CLOCK   :      RB, RB, RB, CS, CS, CS
B. BLOCK II: PRNS  2, 14, 16, 17, 18, 19, 20, 21
   PLANE   : SLOT B2, E1, E3, D2, F3, A4, B3, E2
   CLOCK   :      CS, CS, RB, CS, CS, CS, CS, CS
2. CURRENT ADVISORIES (ADV) AND FORECASTS (FCST):
INFORMATION IS REPEATED FOR SEVEN DAYS AFTER EVENT CONCLUDES
NANU      MSG DATE/TIME   PRN    TYPE  SUMMARY
172-90234 221704Z AUG 90  RPOSN  FCST  REPOSITIONING SCHEDULE
189-90254 120100Z SEP 90  PRN12  ADV   UNUSABLE 254/2254-254/2328
190-90259 160200Z SEP 90  PRN9   ADV   UNUSABLE 259/0029-259/0048
191-90259 161200Z SEP 90  PRN3   ADV   UNUSABLE 259/0850-259/0940
192-90260 172046Z SEP 90  PRN6   ADV   UNUSABLE 260/1325-260/1600
193-90264 211350Z SEP 90  PRN6   ADV   UNUSABLE 264/1200-264/1215
3. REMARKS:
A. PRN21 IS USABLE AS OF DAY 234 (22 AUG 90) AT APPROXIMATELY
1500 UTC. ALTHOUGH THE SATELLITE IS USABLE FOR NAVIGATION AND
TIMING, IT HAS NOT BEEN DECLARED OPERATIONAL AND IS UNDERGOING
TESTING THAT MAY RESULT IN PRN21 BEING SET UNUSABLE WITHOUT
ADVANCE NOTIFICATION.
B. IMPLEMENTATION OF STANDARD POSITIONING SERVICE:
THE CURRENT GPS CONSTELLATION BEGAN BROADCASTING NAVIGATION
MESSAGES AT ACCURACY LEVELS CONSISTENT WITH STANDARD POSITIONING
SERVICE ON 25 MAR 90. GPS IS NOT EXPECTED TO BE DECLARED FULLY
OPERATIONAL UNTIL 1993. ANY GPS USERS ARE OPERATING AT THEIR OWN
RISK.
C. THE SATELLITES WHICH BEGAN REPOSITIONING EARLIER THIS YEAR WILL
CONTINUE GRADUAL CHANGES TO THEIR ORBITAL POSITIONS UNTIL
REPOSITIONING TERMINATE DATES AS SHOWN BELOW:
PRN  TERMINATE  TENTATIVE OUTAGE WINDOWS (UTC)     ACTUAL
16    6 SEP 90  FINAL MANEUVER 249/02:56-250/02:56 249/03:26-249/09:39
13   25 SEP 90  FINAL MANEUVER 268/15:32-269/15:32 * DATE CHANGED *
 3   15 OCT 90  FINAL MANEUVER 288/19:17-289/19:17
11   25 OCT 90  FINAL MANEUVER 298/17:08-299/17:08
14    2 NOV 90  FINAL MANEUVER 306/01:08-307/01:08
18   13 NOV 90  SLOW DOWN      317/02:14-318/02:14
 2   20 NOV 90  FINAL MANEUVER 324/09:26-325/09:26
18   10 DEC 90  FINAL MANEUVER 344/00:29-345/00:29
19   19 DEC 90  SLOW DOWN      353/19:04-354/19:04
19   10 JAN 90  FINAL MANEUVER 010/00:14-011/00:14
4. POINT OF CONTACT: MAJ FAUVER AT (719)550-6379.