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J/other/Ser/177.109    Corrections to HIP proper motions    (Damljanovic+, 2008)
Corrections to the Hipparcos proper motions in declination for 807 stars.
    Damljanovic G., Pejovic N.
   <Serbian Astron. Journal, 177, 109-113 (2008)>
   =2008SerAJ.177..109D
ADC_Keywords: Positional data ; Proper motions

Keywords: astrometry - reference systems


Abstract:
    We used the data on latitude variations obtained from observations
    with 10 classical photographic zenith tubes (PZT) in order to improve
    the Hipparcos proper motions in declinations µδ for 807
    stars. Part of observing programmes, carried out during the last
    century for the purpose of studying the Earth's rotation, were
    realized by using PZT instruments. These observations were performed
    within in the intervals (tens of years) much longer than that of the
    Hipparcos mission (less than 4 years). In addition, the annual number
    of observations for every PZT- programme star is several hundreds on
    the average. Though the accuracy of the star coordinates in the
    Hipparcos Catalogue is by two orders of magnitude better than that of
    the star coordinates from the PZT observations, the large number of
    observations performed a much longer time interval makes it possible
    to correct the Hipparcos proper motions and to improve their accuracy
    with respect to the accuracy given in the Hipparcos Catalogue. Long
    term examinations of latitude and time variations were used to form
    the Earth Orientation Catalogue (EOC-2), aimed at a more accurate
    determination of positions and proper motions for the stars included.
    Our method of calculating the corrections of the proper motions in
    declination from the latitude variations is different from the method
    used in obtaining the EOC-2 Catalogue. Comparing the results we have
    established a good agreement between our µδ and the EOC-2
    ones for the star sample used in the present paper.

Description:
    Here we use the results of latitude observations made with PZT
    instruments over a few decades together with the Hipparcos Catalogue
    data, in order to obtain proper motions in declination more accurate
    than the Hipparcos ones for 807 stars.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table2.dat        60      807   The values of pmDE and e_pmDE for 807 stars:
                             ours, EOC-2 and Hipparcos ones


See also:
            I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
    J/A+A/463/783 : Combined astrometric catalogue EOC-3 (Vondrak+, 2007)
    J/A+A/509/A3  : Earth Orientation Catalog 4 (EOC-4) (Vondrak+, 2010)


Byte-by-byte Description of file: table2.dat

   Bytes Format Units     Label     Explanations

   1-  6  I6    ---       HIP       HIP number (Cat. I/239)
   9- 11  I3    ---       Np        Number of points
  14- 20  F7.2  mas/yr    pmDE      Proper motion along Declination
  23- 26  F4.2  mas/yr    e_pmDE    rms uncertainty on pmDE
  29- 35  F7.2  mas/yr    pmDE(E)   EOC-2 proper motion along Declination
  38- 41  F4.2  mas/yr   e_pmDE(E)  rms uncertainty on pmDEE
  44- 50  F7.2  mas/yr    pmDE(H)   HIP proper motion along Declination
  53- 56  F4.2  mas/yr   e_pmDE(H)  rms uncertainty on pmDEH
      60  A1    ---       Obs       [12-] Observatory code (1)

Note (1): Observatory code as follows:
      1 = star is common to Washington and Mizusawa
      2 = star is common to Mount Stromlo and Punta Indio
      - = star is observed at only one observatory


History:
    From electronic version of the journal
(End)                                      Patricia Vannier [CDS]    11-Jan-2011