2006A&A...449.1271L

Query : 2006A&A...449.1271L

2006A&A...449.1271L - Astronomy and Astrophysics, volume 449, 1271-1279 (2006/4-3)

Astrometric precision of observations at VLT/FORS2.

LAZORENKO P.F.

Abstract (from CDS):

In this paper we test the astrometric precision of VLT/FORS2 observations using a series of CCD frames taken in the Galactic bulge area. A special reduction method based on symmetrization of reference fields was used to reduce the atmospheric image motion. The positional precision of unsaturated R=16mag star images at a 17s exposure and 0.55'' seeing was found to be equal to 300µas. The total error of observations was decomposed into components. It was shown that astrometric error depends mainly on the photon centroiding error of the target (250µas for 16mag stars), while the image motion was much less (110µas). At galactic latitudes to about 20°, precision for a series of frames with a 10 min total exposure was estimated to be 30-50µas for 14-16mag stars, providing the images were not overexposed and the filter Rspecial was used. Error estimates for fields with smaller sky star density are given. We conclude that astrometric observations with large telescopes, under optimal reduction, are never atmospheric limited. The bias caused by differential chromatic refraction and the residual chromatism of LADC are considered and expressions that are valid for correcting color effects in the measured positions are given.

Abstract Copyright: ∼

Journal keyword(s): astrometry - methods: data analysis - atmospheric effects

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 NAME OGLE-TR-132b Pl 10 50 34.5943868112 -61 57 26.138690064           ~ 105 1

Query : 2006A&A...449.1271L

Basic data :
NAME OGLE-TR-132b -- Extra-solar Planet
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types: 		Pl (), Pl? ()
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) : 		10 50 34.5943868112 -61 57 26.138690064 (Optical) [ 0.0367 0.0382 90 ] A 2020yCat.1350....0G
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) : 		10 48 38.6124926916 -61 41 30.695767565 [ 0.0367 0.0382 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) : 		289.2346745035514 -02.3431918378913 [ 0.0367 0.0382 90 ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr : 		-5.463 3.058 [0.047 0.050 90] A 2020yCat.1350....0G
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas): 		0.429 [0.045] A 2020yCat.1350....0G
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding.
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Some important notes on this object about identifications and objects associations.
notes:

Hierarchy : number of linked objects
whatever the membership probability is (see description here ) :

: 1 Display criteria :

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Identifiers (2) :
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NAME OGLE-TR-132b NAME OGLE-TR 132b

References (105 between 1850 and 2024) (Total 105)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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