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Joint astrometric solution of HIPPARCOS and Gaia. A recipe for the Hundred Thousand Proper Motions project

Michalik, Daniel LU ; Lindegren, Lennart LU ; Hobbs, David LU and Lammers, Uwe (2014) In Astronomy & Astrophysics 571.
Abstract
Context. The first release of astrometric data from Gaia is expected in 2016. It will contain the mean stellar positions and magnitudes from the first year of observations. For more than 100 000 stars in common with the HIPPARCOS Catalogue it will be possible to compute very accurate proper motions due to the time difference of about 24 years between the two missions. This Hundred Thousand Proper Motions (HTPM) project is planned to be part of the first release. Aims. Our aim is to investigate how early Gaia data can be optimally combined with information from the HIPPARCOS Catalogue in order to provide the most accurate and reliable results for HTPM. Methods. The Astrometric Global Iterative Solution (AGIS) was developed to compute the... (More)
Context. The first release of astrometric data from Gaia is expected in 2016. It will contain the mean stellar positions and magnitudes from the first year of observations. For more than 100 000 stars in common with the HIPPARCOS Catalogue it will be possible to compute very accurate proper motions due to the time difference of about 24 years between the two missions. This Hundred Thousand Proper Motions (HTPM) project is planned to be part of the first release. Aims. Our aim is to investigate how early Gaia data can be optimally combined with information from the HIPPARCOS Catalogue in order to provide the most accurate and reliable results for HTPM. Methods. The Astrometric Global Iterative Solution (AGIS) was developed to compute the astrometric core solution based on the Gala observations and will be used for all releases of astrometric data from Gaia. We adapt AGIS to process HIPPARCOS data in addition to Gaia observations, and use simulations to verify and study the joint solution method. Results. For the HTPM stars we predict proper motion accuracies between 14 and 134 pas yr-1, depending on stellar magnitude and amount of Gaia data available. Perspective effects will be important for a significant number of HTPM stars, and in order to treat these effects accurately we introduce a formalism called scaled model of kinematics (SMOK). We define a goodness-of-fit statistic which is sensitive to deviations from uniform space motion, caused for example by binaries with periods of 10-50 years. Conclusions. HTPM will significantly improve the proper motions of the HIPPARCOS Catalogue well before highly accurate Gaiaonly results become available. Also, HTPM will allow us to detect long period binary and exoplanetary candidates which would be impossible to detect from Gaia data alone. The full sensitivity will not be reached with the first Gaia release but with subsequent data releases. Therefore HTPM should be repeated when more Gaia data become available. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
astrometry, methods: data analysis, methods: numerical, space vehicles:, instruments, proper motions, planets and satellites: detection
in
Astronomy & Astrophysics
volume
571
publisher
EDP Sciences
external identifiers
  • wos:000345282600021
  • scopus:84910650077
ISSN
0004-6361
DOI
10.1051/0004-6361/201424606
language
English
LU publication?
yes
id
45094303-bd2c-4192-968f-2b01593fa86c (old id 5069085)
date added to LUP
2015-02-25 13:19:20
date last changed
2017-09-03 04:16:42
@article{45094303-bd2c-4192-968f-2b01593fa86c,
  abstract     = {Context. The first release of astrometric data from Gaia is expected in 2016. It will contain the mean stellar positions and magnitudes from the first year of observations. For more than 100 000 stars in common with the HIPPARCOS Catalogue it will be possible to compute very accurate proper motions due to the time difference of about 24 years between the two missions. This Hundred Thousand Proper Motions (HTPM) project is planned to be part of the first release. Aims. Our aim is to investigate how early Gaia data can be optimally combined with information from the HIPPARCOS Catalogue in order to provide the most accurate and reliable results for HTPM. Methods. The Astrometric Global Iterative Solution (AGIS) was developed to compute the astrometric core solution based on the Gala observations and will be used for all releases of astrometric data from Gaia. We adapt AGIS to process HIPPARCOS data in addition to Gaia observations, and use simulations to verify and study the joint solution method. Results. For the HTPM stars we predict proper motion accuracies between 14 and 134 pas yr-1, depending on stellar magnitude and amount of Gaia data available. Perspective effects will be important for a significant number of HTPM stars, and in order to treat these effects accurately we introduce a formalism called scaled model of kinematics (SMOK). We define a goodness-of-fit statistic which is sensitive to deviations from uniform space motion, caused for example by binaries with periods of 10-50 years. Conclusions. HTPM will significantly improve the proper motions of the HIPPARCOS Catalogue well before highly accurate Gaiaonly results become available. Also, HTPM will allow us to detect long period binary and exoplanetary candidates which would be impossible to detect from Gaia data alone. The full sensitivity will not be reached with the first Gaia release but with subsequent data releases. Therefore HTPM should be repeated when more Gaia data become available.},
  articleno    = {A85},
  author       = {Michalik, Daniel and Lindegren, Lennart and Hobbs, David and Lammers, Uwe},
  issn         = {0004-6361},
  keyword      = {astrometry,methods: data analysis,methods: numerical,space vehicles:,instruments,proper motions,planets and satellites: detection},
  language     = {eng},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {Joint astrometric solution of HIPPARCOS and Gaia. A recipe for the Hundred Thousand Proper Motions project},
  url          = {http://dx.doi.org/10.1051/0004-6361/201424606},
  volume       = {571},
  year         = {2014},
}