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Bernese GPS Software Version 5.0 - Bernese GNSS Software

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22. Data Structure<br />

DIFFERENCE OF <strong>GPS</strong>-TIME MINUS UTC-TIME<br />

-------------------------------------<br />

<strong>GPS</strong>-UTC VALID SINCE<br />

(SEC) YYYY MM DD HH MM SS.SS<br />

4. 1985 07 01 00 00 00.00<br />

5. 1988 01 01 00 00 00.00<br />

6. 1990 01 01 00 00 00.00<br />

7. 1991 01 01 00 00 00.00<br />

8. 1992 07 01 00 00 00.00<br />

9. 1993 07 01 00 00 00.00<br />

10. 1994 07 01 00 00 00.00<br />

11. 1996 01 01 00 00 00.00<br />

12. 1997 07 01 00 00 00.00<br />

13. 1999 01 01 00 00 00.00<br />

22.4.7 Leap Seconds<br />

Figure 22.9: The leap second file <strong>GPS</strong>UTC.<br />

Type: ASCII<br />

Directory: ${X}/GEN (UNIX) or %X%\GEN (Windows)<br />

Extension: -<br />

Content: Leap seconds.<br />

Created by: User-defined. Available from BSW aftp server.<br />

Used by: Used by programs POLUPD, QLRINEXO, RXNPRE, RXOBV3, SNX2NQ0.<br />

Example: Figure 22.9 and ${X}/GEN/<strong>GPS</strong>UTC..<br />

The file has to be updated each time a leap second is introduced. Most programs take the<br />

leap second information from the pole file. Programs CODSPP, <strong>GPS</strong>EST, MAUPRP need<br />

the file only if an attitude file for JASON is used.<br />

22.4.8 Nutation Model<br />

Type: ASCII<br />

Directory: ${X}/GEN (UNIX) or %X%\GEN (Windows)<br />

Extension: NUT<br />

Content: Nutation model coefficients.<br />

Created by: User-defined.<br />

Used by: All programs writing and using orbit information.<br />

Example: Figure 22.10 and ${X}/GEN/IAU2000.NUT.<br />

Nutation models IAU80 and IAU2000 are available in <strong>Version</strong> <strong>5.0</strong> which are conforming with<br />

the respective IAU resolutions. The files contain the coefficients for luni-solar and planetary<br />

nutation terms as well as for the computation of the nutation arguments. The IAU2000<br />

precession-nutation model replaces the IAU80 nutation model and is recommended by the<br />

IERS Conventions 2003 [McCarthy and Petit, 2004]. It is based on a non-rigid Earth and<br />

includes 678 lunisolar terms and 687 planetary terms.<br />

In order to increase efficiency the nutation matrix is buffered in a table with tabular interval<br />

of 1 hour. Values in this interval are interpolated linearly. The nutation model file has to<br />

be consequently used for all programs starting with program PRETAB.<br />

For standard orbits generated with <strong>Version</strong> 4.2 the model IAU80 has to be used.<br />

Page 490 AIUB

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