2017A&A...606A..90L


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST04:15:23

2017A&A...606A..90L - Astronomy and Astrophysics, volume 606A, 90-90 (2017/10-1)

Gaia and VLT astrometry of faint stars: Precision of Gaia DR1 positions and updated VLT parallaxes of ultracool dwarfs.

LAZORENKO P.F. and SAHLMANN J.

Abstract (from CDS):

Aims. We compared positions of the Gaia first data release (DR1) secondary data set at its faint limit with CCD positions of stars in 20 fields observed with the Very Large Telescope (VLT) FORS2. We aim at an independent verification of the DR1 astrometric precision taking advantage of the FORS2 position uncertainties which are smaller than one milli-arcsecond (mas).
Methods. In the fields that we observed with FORS2, we projected the Gaia DR1 positions into the CCD plane, performed a polynomial fit between the two sets of matching stars, and carried out statistical analyses of the residuals in positions.
Results. The residual root mean square (rms) roughly matches the expectations given by the Gaia DR1 uncertainties, where we identified three regimes in terms of Gaia DR1 precision: for G~=17-20 stars we found that the formal DR1 position uncertainties of stars with DR1 precisions in the range of 0.5-5mas are underestimated by 63±5%, whereas the DR1 uncertainties of stars in the range 7-10mas are overestimated by a factor of two. For the best-measured and generally brighter G~=16-18 stars with DR1 positional uncertainties of <0.5mas, we detected 0.44±0.13mas excess noise in the residual rms, whose origin could be in both FORS2 and Gaia DR1. By adopting Gaia DR1 as the absolute reference frame, we refined the pixel scale determination of FORS2,leading to minor updates to the parallaxes of 20 ultracool dwarfs that we published previously. We also updated the FORS2 absolute parallax of the Luhman 16 binary brown dwarf system to 501.42±0.11mas.

Abstract Copyright: © ESO, 2017

Journal keyword(s): astrometry - methods: data analysis - surveys - catalogs - parallaxes - stars: individual: WISE J104915.57-531906.1 - stars: individual: WISE J104915.57-531906.1

Simbad objects: 21

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Number of rows : 21

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 DENIS J061549.3-010041 BD* 06 15 49.3549619421 -01 00 41.659094164         17.00 L2.5 12 0
2 DENIS J063001.4-184014 LM* 06 30 01.4609493271 -18 40 14.825550559         15.88 M9.0V 8 0
3 DENIS J064414.3-284141 LM* 06 44 14.4139030405 -28 41 41.749065298         16.96 M9.5 7 0
4 DENIS J065219.7-253450 BD* 06 52 19.7631187838 -25 34 50.466131332       19.3 15.96 L0.0 16 0
5 2MASS J07164790-0630369 BD* 07 16 47.9039277022 -06 30 36.942708123         17.46 L1.0 10 0
6 DENIS J075116.4-253043 BD* 07 51 16.3951502000 -25 30 43.042204212         16.53 L1.5 16 0
7 DENIS J080511.0-315811 LM* 08 05 11.0219343546 -31 58 11.464454559         16.01 M8.0 6 0
8 DENIS J081231.6-244442 BD* 08 12 31.7163139884 -24 44 42.472716658       19.458 17.27 L1.5 14 0
9 DENIS J082303.1-491201 BD* 08 23 03.1457502969 -49 12 01.265841098       20.020 17.14 L1.5 13 0
10 SSSPM J0829-1309 BD* 08 28 34.1713208171 -13 09 19.842042734         16.07 L2 40 0
11 DENIS J104827.8-525418 BD* 10 48 27.8698669504 -52 54 18.129558996       19.965 17.25 L1.5 7 0
12 NAME Luhman 16 ** 10 49 18.915 -53 19 10.08   16.86 16.20   14.95 L7.5+T0.5 72 0
13 DENIS J115748.0-484442 BD* 11 57 48.0922231567 -48 44 42.844880952         17.25 L1.0 7 0
14 1RXS J115928.5-524717 LM* 11 59 27.3607245322 -52 47 18.910528784       16.617 14.49 M9Ve 24 0
15 DENIS J125310.8-570924 BD* 12 53 10.9620497223 -57 09 24.848571988         16.74 L0.5 8 0
16 2MASS J15200224-4422419 ** 15 20 02.24160 -44 22 41.9880       19.4 16.89 L1.5+L4.5 21 0
17 DENIS J170547.4-544151 LM* 17 05 47.4269185940 -54 41 51.339685217       19.090 16.66 M8.5 6 0
18 DENIS J173342.3-165449 BD* 17 33 42.2753954344 -16 54 50.117721351         16.82 L1.0 9 0
19 DENIS J174534.6-164053 BD* 17 45 34.6668182094 -16 40 53.961533063         17.11 L1.5 12 0
20 DENIS J175629.6-451822 LM* 17 56 29.63040 -45 18 22.4784       17.982 15.46 M9.0 7 0
21 DENIS J175656.1-480509 BD* 17 56 56.2079723621 -48 05 09.629197908         16.76 L0.0 6 0

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2020.07.08-04:15:23

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