J/AJ/143/70 Differential reddening in Milky Way globulars (Alonso-Garcia+, 2012)
Uncloaking globular clusters in the inner Galaxy.
Alonso-Garcia J., Mateo M., Sen B., Banerjee M., Catelan M., Minniti D.,
von Braun K.
<Astron. J., 143, 70 (2012)>
=2012AJ....143...70A 2012AJ....143...70A
ADC_Keywords: Milky Way ; Clusters, globular ; Extinction
Keywords: dust, extinction - Galaxy: bulge - Galaxy: evolution -
globular clusters: general - Hertzsprung-Russell and C-M diagrams -
stars: horizontal-branch
Abstract:
Extensive photometric studies of the globular clusters located toward
the center of the Milky Way have been historically neglected. The
presence of patchy differential reddening in front of these clusters
has proven to be a significant obstacle to their detailed study. We
present here a well defined and reasonably homogeneous photometric
database for 25 of the brightest Galactic globular clusters located in
the direction of the inner Galaxy. These data were obtained in the B,
V, and I bands using the Magellan 6.5m Telescope and the Hubble Space
Telescope. A new technique is extensively used in this paper to map
the differential reddening in the individual cluster fields, and to
produce cleaner, dereddened color-magnitude diagrams for all the
clusters in the database. Subsequent papers will detail the
astrophysical analysis of the cluster populations, and the properties
of the obscuring material along the clusters' lines of sight.
Description:
We obtained optical photometric data for our sample of 25 GGCs. The
GGCs were observed over four nights, 2005 May 30 to June 2, with the
Magellan 6.5m Baade Telescope located at the Las Campanas Observatory
(LCO) in Chile, using the Inamori Magellan Areal Camera and
Spectrograph (IMACS) in imaging mode. All fields were observed using
standard Johnson-Cousins B, V, and I filters. In order to obtain
useful photometry of the inner regions of the more centrally crowded
clusters, we supplemented our Magellan images with images taken with
the Advanced Camera for Surveys (ACS) on board the HST in 2006
February-June (Prog 10573). Five clusters of our sample were observed
using the f435w(B435), f555w(V555), and f814w(I814) filters. To
better calibrate our photometry, we also used images available through
the HST data archive for all the clusters in our sample.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 25 Characteristics of the globular clusters in our
sample according to the 2010 version of the Harris
(1996, Cat. VII/195, superseded by Cat. VII/202)
Galactic Globular Cluster (GGC) Catalog
table8.dat 51 839211 Differential reddening, with respect to our ridgeline
extinction zero points, of a selected set of
coordinates across the field of our sampled clusters
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
VII/103 : Galactic Globular Clusters (Monella 1985)
J/AJ/140/1043 : GCs in M31 and the Galaxy (van den Bergh+, 2010)
J/AJ/133/1287 : JHK photometry of 24 Galactic GCs (Valenti+, 2007)
J/A+A/450/105 : Properties of 153 Galactic globular clusters (Bica+, 2006)
J/AJ/132/2171 : VI photometry of NGC 6293 and NGC 6541 (Lee+, 2006)
J/ApJ/628/729 : CCD BVIc photometry of M10 stars (Pollard+, 2005)
J/ApJ/608/243 : CCD BVI photometry of M12 stars (Hargis+, 2004)
J/MNRAS/349/1278 : BVI photometry of M22 (Monaco+, 2004)
J/AJ/124/1486 : M4 UBV color-magnitude diagrams (Mochejska+, 2002)
J/A+A/391/945 : HST photometry of 74 galactic GCs (Piotto+, 2002)
J/AJ/121/916 : HST obs. of NGC 2298, 5897, 6535, and 6626 (Testa+, 2001)
J/A+AS/145/451 : Nearby GCs photometric catalog (Rosenberg+, 2000)
J/A+AS/144/5 : Nearby GCs photometric catalog (Rosenberg+, 2000)
J/A+AS/135/391 : VI CCD photometry of NGC 6553 (Sagar+ 1999)
J/A+A/331/70 : JKVI photometry of NGC 6553 stars (Guarnieri+ 1998)
J/AJ/110/652 : VI photometry in NGC 6352 (Fullton+ 1995)
J/ApJS/93/161 : CCD photometry of 6 globular clusters (Sarajedini+ 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Cluster Cluster identification
10- 13 A4 --- OName Other cluster identification
15- 20 F6.2 deg GLON Galactic longitude
22- 27 F6.2 deg GLAT Galactic latitude
29- 31 F3.1 kpc Rgc Galactocentric distance
33- 36 F4.1 kpc Rsun Distance from the Sun
38- 42 F5.2 [Sun] [Fe/H] Metallicity
44- 47 F4.2 mag <E(B-V)> Mean reddening of the cluster
49- 53 F5.2 mag (m-M)V Apparent distance modulus
55- 59 F5.2 mag VMag Absolute visual magnitude (cluster luminosity)
61- 65 F5.2 arcmin rt Tidal radius
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Cluster Cluster identification
10- 13 A4 --- OName Other cluster identification
15- 23 F9.5 deg RAdeg [245.77/295.17] Right Ascension (J2000) (1)
25- 33 F9.5 deg DEdeg [-53.79/-1.80] Declination (J2000) (1)
35- 40 F6.3 mag dE(B-V) [-0.23/0.57] Differential reddening
δE(B-V) (changes in the extinction
across the field) (2)
42- 46 F5.3 mag e_dE(B-V) Error in dE(B-V)
48- 51 F4.2 arcmin BW [0.5/7.39] Bandwidth used in the resolution map
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Note (1): Position of the point in the extinction map.
We derived coordinates by comparison with bright stars obtained in
each field from the 2MASS catalog stars (Cat. II/246) available
through the Infrared Processing and Analysis Center (IPAC) Web site
(http://www.ipac.caltech.edu/).
Note (2): With respect to our ridgeline extinction zeropoints.
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History:
From electronic version of the journal
References:
Alonso-Garcia et al. Paper I. 2011AJ....141..146A 2011AJ....141..146A
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 02-May-2013