2006A&A...454.1029A


Query : 2006A&A...454.1029A

2006A&A...454.1029A - Astronomy and Astrophysics, volume 454, 1029-1045 (2006/8-2)

Ground-based CCD astrometry with wide field imagers. I. Observations just a few years apart allow decontamination of field objects from members in two globular clusters.

ANDERSON J., BEDIN L.R., PIOTTO G., YADAV R.S. and BELLINI A.

Abstract (from CDS):

This paper is the first of a series of papers in which we will apply the methods we have developed for high-precision astrometry (and photometry) with the Hubble Space Telescope (HST) to the case of wide-field ground-based images. In particular, we adapt the software originally developed for WFPC2 to ground-based, wide field images from the WFI at the ESO 2.2m telescope. In this paper, we describe in details the new software, we characterize the WFI geometric distortion, discuss the adopted local transformation approach for proper-motion measurements, and apply the new technique to two-epoch archive data of the two closest Galactic globular clusters: NGC 6121 (M4) and NGC 6397. The results of this exercise are more than encouraging. We find that we can achieve a precision of ∼7mas (in each coordinate) in a single exposure for a well-exposed star, which allows a very good cluster-field separation in both M4, and NGC 6397, with a temporal baseline of only 2.8, and 3.1-years, respectively.

Abstract Copyright:

Journal keyword(s): astrometry - globular clusters: individual: NGC 6397 - globular clusters: individual: NGC 6121 (M4) - techniques: image processing

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NGC 2477 OpC 07 52 11 -38 32.2   6.64 5.8     ~ 268 0
2 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3231 0
3 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1758 0
4 NGC 6397 GlC 17 40 42.09 -53 40 27.6   7.39 5.17     ~ 1876 1
5 NAME Baade Window reg 18 03.5 -30 01           ~ 575 3
6 NGC 6522 GlC 18 03 34.08 -30 02 02.3   10.68 9.48     ~ 496 1
7 NGC 6528 GlC 18 04 49.61 -30 03 20.8   12.12 10.65     ~ 497 0
8 NAME Galactic Bulge reg ~ ~           ~ 3846 0

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2022.05.24-11:47:16

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