SUBJ: GPS STATUS 12 APR 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
   PLANE   : SLOT B2, E1, D2, F2, F3, A4, TBD
   CLOCK   :      CS, CS, RB, CS, CS, CS, TBD
2. CURRENT ADVISORIES (ADV) AND FORECASTS (FCST):
INFORMATION IS REPEATED FOR SEVEN DAYS AFTER EVENT CONCLUDES
NANU      MSG DATE/TIME   PRN    TYPE  SUMMARY
061-90093 030400Z APR 90  PRN13  ADV   UNUSABLE 93/0812-93/0824
062-90093 031351Z APR 90  PRN18  FCST  CHANGE REPHASING TO 6 APR
062-90093 031830Z APR 90  PRN6   ADV   UNUSABLE 93/1500-93/1530
063-90094 042041Z APR 90  PRN3   FCST  UNUSABLE 95/0400-95/1000
064-90095 050300Z APR 90  PRN3   FCST  RESCIND #063-90094
065-90095 051720Z APR 90  PRN2   FCST  UNUSABLE 98/0400-98/1000
066-90097 071000Z APR 90  PRN18  ADV   UNUSABLE 97/0318 UFN
067-90097 072045Z APR 90  PRN18  ADV   USABLE 97/1902
068-90098 080900Z APR 90  PRN3   ADV   UNUSABLE 98/0410-98/0710
069-90099 092126Z APR 90  PRN19  FCST  CHANGE REPHASING TO 11 APR
070-90101 111030Z APR 90  PRN19  ADV   UNUSABLE 101/0421-101/0634
071-90101 111653Z APR 90  PRN19  FCST  CHANGE REPHASING TO 12 APR
072-90102 121856Z APR 90  PRN19  ADV   UNUSABLE 102/0440-102/1411
3. REMARKS:
A. 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.
4. SATELLITE REPOSITIONING:
PRN  INITIATE  TERMINATE#1 TERMINATE#2 UNUSABLE (DAY/UTC)
11   15 MAR 90 31 OCT 90                74/0335-75/0225   ACTUAL
 3   20 MAR 90 17 OCT 90                79/0700-79/1220   ACTUAL
13   29 MAR 90  3 OCT 90                88/0142-88/1105   ACTUAL
18    7 APR 90 24 NOV 90   8 DEC 90     97/0318-97/1902   ACTUAL
19   11 APR 90                         101/0421-101/0634  RESCHD
19   12 APR 90 31 DEC 90               102/0440-102/1411  ACTUAL
 9   19 APR 90 19 APR 90               109/0928-110/0928  FORECAST
16   26 APR 90 20 SEP 90               116/1317-117/1317  FORECAST
 2    3 MAY 90  1 DEC 90               TBD
14   13 MAY 90 10 NOV 90               TBD
12   20 MAY 90 20 MAY 90               TBD
5. PRN20 ALMANAC IS AVAILABLE IN THE NAVIGATION BROADCAST.
6. POINT OF CONTACT: MAJ FAUVER AT (719)550-6379