SUBJ: GPS STATUS 28 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
195-90264 211801Z SEP 90  PRN20  FCST  UNUSABLE 267/0950-268/0350
196-90266 231500Z SEP 90  PRN12  ADV   UNUSABLE 266/0816-266/0824
197-90267 242215Z SEP 90  PRN16  ADV   CLOCK    265/1800-265/2120
198-90267 242217Z SEP 90  PRN6   ADV   UNUSABLE 267/2000-267/2012
199-90268 251744Z SEP 90 21/13/2 FCST  UPDATE: REPOSITIONING SCHD
200-90269 260645Z SEP 90  PRN12  ADV   UNUSABLE 269/0413-269/0427
201-90269 251230Z SEP 90  PRN6   ADV   UNUSABLE 269/0651-269/0725
202-90270 272330Z SEP 90  PRN2   ADV   UNUSABLE 270/2158-270/2205
203-90271 280615Z SEP 90  PRN11  ADV   UNUSABLE 271/0535-271/0555
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
21    2 OCT 90  STATION KEEPNG 275/00:00-276/00:00 *** ADD ***
13    4 OCT 90  FINAL MANEUVER 277/15:32-278/15:32 ***CHANGE***
 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   19 NOV 90  FINAL MANEUVER 323/09:26-324/09:26 ***CHANGE***
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.