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The Tycho-Gala astrometric solution. How to get 2.5 million parallaxes with less than one year of Gala data

Michalik, Daniel LU ; Lindegren, Lennart LU and Hobbs, David LU (2015) In Astronomy & Astrophysics 574.
Abstract
Context. The first release of astrometric data from Gala will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of Gala data with HIPPARCOS prior information (HTPM). Aims. We study the potential of using the positions from the Tycho-2 Catalogue as additional information for a joint solution with early Gala data. We call this the Tycho -Gain astrometric solution (TGAS). Methods. We adapt Gala's Astrornetric Global Iterative Solution (AGIS) to incorporate Tycho information, and use simulated Gala observations to demonstrate the feasibility of TGAS and to estimate its performance. Results. Using six to twelve months of Gala data, TGAS could deliver positions,... (More)
Context. The first release of astrometric data from Gala will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of Gala data with HIPPARCOS prior information (HTPM). Aims. We study the potential of using the positions from the Tycho-2 Catalogue as additional information for a joint solution with early Gala data. We call this the Tycho -Gain astrometric solution (TGAS). Methods. We adapt Gala's Astrornetric Global Iterative Solution (AGIS) to incorporate Tycho information, and use simulated Gala observations to demonstrate the feasibility of TGAS and to estimate its performance. Results. Using six to twelve months of Gala data, TGAS could deliver positions, parallaxes, and annual proper motions for the 2.5 million Tycho -2 stars, with sub-milliarcsecond accuracy. TGAS overcomes some of the limitations of the FITPM project and allows its execution half a year earlier. Furthermore, if the parallaxes from HIPPARCOS are not incorporated in the solution, they can be used as a consistency check of the TOAS/IITPM results. (Less)
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organization
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Contribution to journal
publication status
published
subject
keywords
astrometry, methods: data analysis, methods: numerical, space vehicles:, instruments, parallaxes proper motions
in
Astronomy & Astrophysics
volume
574
publisher
EDP Sciences
external identifiers
  • wos:000349467000115
  • scopus:84922271812
ISSN
0004-6361
DOI
10.1051/0004-6361/201425310
language
English
LU publication?
yes
id
13f89826-e3f9-413b-9dbd-c6f857add77e (old id 5305594)
date added to LUP
2015-04-23 16:56:10
date last changed
2017-11-19 03:49:23
@article{13f89826-e3f9-413b-9dbd-c6f857add77e,
  abstract     = {Context. The first release of astrometric data from Gala will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of Gala data with HIPPARCOS prior information (HTPM). Aims. We study the potential of using the positions from the Tycho-2 Catalogue as additional information for a joint solution with early Gala data. We call this the Tycho -Gain astrometric solution (TGAS). Methods. We adapt Gala's Astrornetric Global Iterative Solution (AGIS) to incorporate Tycho information, and use simulated Gala observations to demonstrate the feasibility of TGAS and to estimate its performance. Results. Using six to twelve months of Gala data, TGAS could deliver positions, parallaxes, and annual proper motions for the 2.5 million Tycho -2 stars, with sub-milliarcsecond accuracy. TGAS overcomes some of the limitations of the FITPM project and allows its execution half a year earlier. Furthermore, if the parallaxes from HIPPARCOS are not incorporated in the solution, they can be used as a consistency check of the TOAS/IITPM results.},
  articleno    = {A115},
  author       = {Michalik, Daniel and Lindegren, Lennart and Hobbs, David},
  issn         = {0004-6361},
  keyword      = {astrometry,methods: data analysis,methods: numerical,space vehicles:,instruments,parallaxes proper motions},
  language     = {eng},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {The Tycho-Gala astrometric solution. How to get 2.5 million parallaxes with less than one year of Gala data},
  url          = {http://dx.doi.org/10.1051/0004-6361/201425310},
  volume       = {574},
  year         = {2015},
}