NOAA KLM User's Guide

Appendix A

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APPENDIX A: APT Predict (TBUS) Bulletin

APT Predict (TBUS) Bulletin Code

The TBUS is a national practice code form used by the United States to transmit information for predicting the path or locating the position of polar orbiting environmental satellites. It is transmitted daily, at about 1900Z, by KWBC Washington, DC, on the Global Telecommunications Service network.

The TBUS-1 code form is used to convey information about satellites that are descending in daylight (i.e., north to south direction of travel in daytime), while the TBUS-2 code form relates to satellites that are ascending in daylight (south to north). Figure A-1 shows a schematic of the information given in TBUS-1 and TBUS-2 bulletins.

This appendix contains the code forms for TBUS-1 and TBUS-2, a list of the satellite identifiers used in TBUS messages, an explanation of code symbols, samples of an APT Predict (TBUS) bulletin and a Two Line Element message, and how they can be decoded properly.

Figure A-1 is a schematic representation of information conveyed in TBUS-1 and TBUS-2.

Table A-1. Code Symbols for Heading and Parts I-III of the TBUS message.
Code Symbol Meaning
MM Month
DD Day
SS Satellite (see Table A-2)
NNNN Orbit number
HH Hour
mm Minutes
ss Seconds
Q Octant of Globe (see Figure A.3-2)
LoLo Longitude (tens and units)
1o1o Longitude (tenths and hundredths)
T Group indicator (orbital period)
L Group indicator (nodal period)
aa Altitude in hundreds and tens of kilometers
La Latitude (tens)
1a Latitude (tenths)

Table A-2 contains the numbers used in TBUS bulletins to identify the satellite.

Table A-2. Satellite identifier in TBUS bulletins.
Numbers Meaning
10 - 19 ITOS series satellites
20 - 29 SMS/GOES series satellites
30 TIROS-N
31 NOAA-6
32 NOAA-7
33 NOAA-8
34 NOAA-9
35 NOAA-10
36 NOAA-11
37 NOAA-12
38 NOAA-14
34 NOAA-15
36 NOAA-16
40 - 49 NOAA-M through -N' satellites



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