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David Hobbs. Photo.

David Hobbs


David Hobbs. Photo.

Combining and Comparing Astrometric Data from Different Epochs: A Case Study with Hipparcos and Nano-JASMINE


  • Daniel Michalik
  • Lennart Lindegren
  • David Hobbs
  • Uwe Lammers
  • Yoshiyuki Yamada

Summary, in English

The Hipparcos mission (1989-1993) resulted in the first space-based stellar catalogue including measurements of positions, parallaxes and annual proper motions accurate to about one milli-arcsecond. More space astrometry missions will follow in the near future. The ultra-small Japanese mission Nano-JASMINE (launch in late 2013) will determine positions and annual proper motions with some milli-arcsecond accuracy. In mid 2013 the next-generation ESA mission Gala will deliver some tens of micro-arcsecond accurate astrometric parameters. Until the final Gala catalogue is published in early 2020 the best way of improving proper motion values is the combination of positions from different missions separated by long time intervals. Rather than comparing positions from separately reduced catalogues, we propose an optimal method to combine the information from the different data sets by making a joint astrometric solution. This allows to obtain good results even when each data set alone is insufficient for an accurate reduction. We demonstrate our method by combining Hipparcos and simulated Nano-JASMINE data in a joint solution. We show a significant improvement over the conventional catalogue combination.


  • Lund Observatory - Has been reorganised

Publishing year







Astronomical Data Analysis Software and Systems XXI (ASP Conference Series)



Document type

Conference paper


Astronomical Society of the Pacific (ASP)


  • Astronomy, Astrophysics and Cosmology

Conference name

21st Annual Conference on Astronomical Data Analysis Software and Systems

Conference date

2011-11-06 - 2011-11-10

Conference place

Paris, France