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Clock calibration and leap Second handling in EXSAS
 

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                                          Last change: 23-JUL-1997

    Contents:
   ==========
                 1.) The ROSAT Space Craft Clock Calibration
                 2.) Residuals from the space craft clock fits 
                     for the years 1990/97
                 3.) Leap Second handling in EXSAS
                
 

  1.)  The ROSAT Space Craft Clock Calibration
  
        ===============================================================  
       	  Update of the ROSAT scc/utc conversion table : Version 2_97
        ===============================================================

        The table  scc_to_utc2.tbl contains the space craft clock (scc) 
        to universal coordinated time correlation (UTC) valid up to 
        08-JUL-1997 and was last updated on 15-JUL-1997.

        The EXSAS home directory of this table is $EXSAS_CAL (for UNIX)
        or XEXSAS:[CAL] (for VMS). 

	Use the MIDAS command INTAPE/FITS to restore the file if you have
        got the *.tfits version of the file and be sure that the name of 
        the table you create is scc_to_utc2.tbl

        The file discriptors:

                    Version, Validity, Origin and Producer

        are defined for identification purpose. I propose that for 
        the same reason at least the "VERSION" and "ORIGIN" of the 
        calibration table used for the timing analysis should be 
        acknowledged with the results. 
        

    NOTE:  Residuals of the scc/utc fits are the order 3-5 ms over 
           a year. Postscript files which depict the residuals are 
           available for the years 1990-1997 from the following links:




 
  2.)  Leap Second handling in EXSAS
 ====================================

  Beginning from the EXSAS version 97-JUL, leap seconds are read in 
  from a leap second file leap_sec.tbl. This file is updated regularly 
  and contains all leap seconds beginning from 1-JUL-1972. All EXSAS 
  routines which requires this file are looking for it by default in 
  the EXSAS calibration area. However beginning from EXSAS version 
  97-JUL all timing routines which require the leap second information 
  provide the option to use also a user-defined table which keeps the 
  required leap-second information.

  In addition, the leap_sec.tbl file has got the following table 
  descriptors:
 
          VERSION:          2_97
          ORIGIN:           EXSAS
          LAST_UPDATED:     05-FEB-1997
        
  which are presented for information purpose during the barycentring 
  procedure (e.g. by using CORRECT/ORBIT).

  In the case of further questions please report to:
  xray-info @ mpe . mpg . de
  
 



 Werner Becker, MPE-Garching, 23-JUL-1997
     (web @ mpe . mpg . de)

 

© X-Ray Group at MPE (group)
last update:1998/01/09 11:10:52, editor of this page:Werner Becker


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