SUBJ: GPS STATUS 09 JAN 91
1. SATELLITES, PLANES AND CLOCKS (CS=CESIUM RB=RUBIDIUM):
A. BLOCK I : PRNS  3,  6,  9, 11, 12, 13
   PLANE   : SLOT C4, A3, A2, C3, A1, C1
   CLOCK   :      RB, RB, RB, CS, CS, CS
B. BLOCK II: PRNS  2, 14, 15, 16, 17, 18, 19, 20, 21, 23
   PLANE   : SLOT B3, E1, D2, E3, D3, F3, A4, B2, E2, E4
   CLOCK   :      CS, CS, CS, CS, CS, 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
266-90345 111315Z DEC 90  9      ADV   UNUSABLE 345/1305-UFN
276-90365 311942Z DEC 90  16     FCST  UNUSABLE 007/1200-010/1200
001-91002 021713Z JAN 91  3      FCST  UNUSABLE 009/1300-009/1700
002-91003 030200Z JAN 91  23     FCST  UNUSABLE 004/1600-007/1600
003-91005 052330Z JAN 91  6      ADV   UNUSABLE 005/2252-005/2300
004-91006 060900Z JAN 91  6      ADV   UNUSABLE 006/0800-006/0814
005-91006 062230Z JAN 91  23     ADV   USABLE   006/2049
006-91006 062230Z JAN 91  13     ADV   UNUSABLE 006/2032-006/2045
007-91007 071800Z JAN 91  23     FCST  UNUSABLE 011/1315-012/1315
008-91007 072303Z JAN 91  6      ADV   UNUSABLE 007/2206-007/2240
009-91009 092005Z JAN 91  16     ADV   USABLE   009/1639
010-09009 092007Z JAN 91  3      ADV   USABLE   009/1855
3. REMARKS:
A. REF NANU #057-90088: 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.
B. REF NANU #265-90345: PRN23 WAS LAUNCHED ON DAY 330 (26 NOV 90).
THE SATELLITE WAS USABLE FOR NAVIGATION BEGINNING DAY 344
(10 DEC 90) AT APPROXIMATELY 2345 UTC.
C.  REF NANU #266-90345: PRN9 WAS SET UNUSABLE ON DAY 345
(11 DEC 90) AT APPROXIMATELY 1305 UTC.
D. REF NANU #276-90365: PRN16 WILL BE USING A CESIUM FREQUENCY
STANDARD FOLLOWING THE UPCOMING SCHEDULED MAINTENANCE.
4. POINT OF CONTACT: MAJ FAUVER AT (719)550-6379.