GPS OPERATIONAL ADVISORY 90099.OA1
SUBJ: GPS STATUS 9 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
056-90088 291650Z MAR 90  PRN13  ADV   UNUSABLE 88/0142-88/1105
057-90088 300004Z MAR 90  BLKII  ADV   SPS ACCURACY LEVEL
057-90089 300500Z MAR 90  PRN12  ADV   UNUSABLE 89/0200-0240
058-90090 310144Z MAR 90  PRN9   ADV   USABLE 90/0045
059-90090 312300Z MAR 90  PRN3   ADV   UNUSABLE 90/2204-2215
060-90092 021700Z MAR 90  PRN12  ADV   UNUSABLE 92/1954-92/2005
061-90093 030400Z MAR 90  PRN13  ADV   UNUSABLE 93/0812-93/0824
062-90093 031351Z MAR 90  PRN18  FCST  CHANGE REPHASING TO 6 APR
062-90093 031830Z MAR 90  PRN6   ADV   UNUSABLE 93/1500-93/1530
063-90094 042041Z MAR 90  PRN3   FCST  UNUSABLE 95/0400-95/1000
064-90095 050300Z MAR 90  PRN3   FCST  RESCIND #063-90094
065-90095 051720Z MAR 90  PRN2   FCST  UNUSABLE 98/0400-98/1000
066-90097 071000Z MAR 90  PRN18  ADV   UNUSABLE 97/0318 UFN
067-90097 072045Z MAR 90  PRN18  ADV   USABLE 97/1902
068-90098 080900Z MAR 90  PRN3   ADV   UNUSABLE 98/0410-98/0710
069-90099                 PRN19  FCST  CHANGE REPHASING TO 11 APR
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    6 APR 90 24 NOV 90   8 DEC 90     96/1207-97/1207   FORECAST
19   11 APR 90 31 DEC 90               101/0938-103/0938  FORECAST
 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
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