Volume 541, May 2012
|Number of page(s)||10|
|Section||Celestial mechanics and astrometry|
|Published online||16 May 2012|
1 Observatório do Valongo/UFRJ, Ladeira Pedro Antonio 43, CEP 20.080-090 Rio de Janeiro - RJ, Brazil
2 Observatório Nacional/MCT, R. General José Cristino 77, CEP 20921-400 Rio de Janeiro - RJ, Brazil
3 Observatoire de Paris-Meudon/LESIA, 5 place Jules Janssen, Meudon, France
4 Université Pierre et Marie Curie, Institut Universitaire de France, Paris, France
5 Centro Universitário Estadual da Zona Oeste, Av. Manual Caldeira de Alvarenga 1203, CEP: 23.070-200 Rio de Janeiro - RJ, Brazil
Received: 28 October 2011
Accepted: 9 March 2012
Context. We study large trans-Neptunian objects (TNOs) using stellar occultations.
Aims. We derive precise astrometric predictions for stellar occultations by Eris, Haumea, Ixion, Makemake, Orcus, Quaoar, Sedna, Varuna, 2002 TX300, and 2003 AZ84 for 2011–2015. We construct local astrometric catalogs of stars complete to magnitudes as faint as R = 18 − 19 in the UCAC2 (Second US Naval Observatory CCD Astrograph Catalog) frame covering the sky path of these objects.
Methods. During 2007–2009, we carried out an observational program at the ESO2p2/WFI (2.2 m Max-Planck ESO telescope with the Wide Field Imager) instrument. The observations covered the sky path of the selected targets from 2008 to 2015. We performed the astrometry of 316 GB images using the Platform for Reduction of Astronomical Images Automatically (PRAIA). With the help of field distortion patterns derived for the WFI mosaic of CCDs, we reduced the overlapping mosaics of CCDs.
Results. We derive positions in the UCAC2 frame with 40 mas precision for stars up to the catalog magnitude completeness limit (about R = 19). New stellar proper motions are also determined with 2MASS (Two Micron All Sky Survey) and the USNO B1.0 (United States Naval Observatory B 1.0) catalog positions as a first epoch. Astrometric catalogs with proper motions were produced for each TNO, containing more than 5.35 million stars covering the sky paths with 30′ width in declination. The magnitude completeness is about R = 19 with a limit of about R = 21. We predicted 2717 stellar occultation candidates for all targets. Ephemeris offsets with about from 50 mas to 100 mas precision were applied to each TNO orbit to improve the predictions. They were obtained during 2007–2010 from a parallel observational campaign carried out with telescopes from 0.6 m to 2.2 m in size.
Conclusions. This extends our previous work for the Pluto system to large TNOs, using the same observational and astrometric procedures. The obtained astrometric catalogs are useful for follow-up programs at small to large telescopes used to improve the candidate star positions and TNO ephemeris. They also furnish valuable photometric information for the field stars. For each TNO, updates on the ephemeris offsets and candidate star positions (geometric conditions of predictions and finding charts) are made available by the group at http://www.lesia.obspm.fr/perso/bruno-sicardy/.
Key words: astrometry / occultations / Kuiper belt: general
Tables of predictions for stellar occultations by Eris, Haumea, Ixion, Makemake, Orcus, Quaoar, Sedna, Varuna, 2002 TX300, and 2003 AZ84 for 2011–2015 and respective Catalog of star positions for 2008–2015 sky path are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/541/A142
Also based on observations made at Laboratório Nacional de Astrofísica (LNA), Itajubá-MG, Brazil.
Associate researcher at Observatoire de Paris/IMCCE, 77 avenue Denfert Rochereau, 75014 Paris, France.
Associate researcher at Observatoire de Paris/SYRTE, 77 avenue Denfert Rochereau, 75014 Paris, France.
© ESO, 2012
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