J/A+A/654/A6 Aperture photometry of the M31 PHAT clusters (Naujalis+, 2021)
Deriving physical parameters of unresolved star clusters.
VI. Adaptive aperture photometry of the M31 PHAT star clusters.
Naujalis R., Stonkute R., Vansevicius V.
<Astron. Astrophys. 654, A6 (2021)>
=2021A&A...654A...6N 2021A&A...654A...6N (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Photometry, HST ; Optical ; Infrared ;
Ultraviolet
Keywords: galaxies: individual: M31 - galaxies: star clusters: general
Abstract:
This study is the sixth of a series that investigates degeneracy and
stochasticity problems present in the determination of the age, mass,
extinction, and metallicity of partially resolved or unresolved star
clusters in external galaxies when using Hubble Space Telescope
broadband photometry. In the fifth publication, it was noticed that
inconsistencies in cluster colour indices, which arise due to
projected foreground and background stars on the apertures, enhance
age-metallicity-extinction degeneracies.
In this work we aim to present new aperture photometry results for a
sample of star clusters from the M31 Panchromatic Hubble Andromeda
Treasury (PHAT) survey.
We employed two methods of aperture photometry. The first method is
ordinary aperture photometry to measure total cluster fluxes. The
second method was introduced to avoid the brightest foreground and
background stars that project onto large apertures. This method
employs smaller apertures, adapted to cover a central part of
clusters, and applies an aperture correction, derived for the F475W
passband, to other passbands. We note that this procedure is valid only
for clusters without prominent systematic gradients of colour indices
beyond half-light radii.
We present two catalogues of star cluster aperture photometry
(produced by applying ordinary aperture photometry and adaptive
aperture photometry methods) with estimated uncertainties for a sample
of 1181 star clusters from the M31 PHAT survey. Compared to the M31
PHAT fundamental star cluster aperture photometry catalogue published
by Johnson et al., there are changes made in the following: cluster
centre coordinates, aperture sizes, and sky background estimates.
Description:
We present new aperture photometry results for a sample of star
clusters from the M31 PHAT survey. We employed two methods of aperture
photometry. The first method is ordinary aperture photometry to
measure total cluster fluxes (magnitudes T). The second method was
introduced to avoid the brightest foreground and background stars that
project onto large apertures. This method employs smaller apertures,
adapted to cover a central part of clusters, and applies an aperture
correction, derived for the F475W passband, to other passbands
(magnitudes C). We note that this procedure is valid only for clusters
without prominent systematic gradients of colour indices beyond
half-light radii. We present two catalogues of star cluster aperture
photometry (produced by applying ordinary aperture photometry and
adaptive aperture photometry methods) with estimated uncertainties for
1181 star clusters. Compared to the M31 PHAT fundamental star cluster
aperture photometry catalogue published by Johnson et al., there are
changes made in the following: cluster centre coordinates, aperture
sizes, and sky background estimates.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 113 1181 M31 star cluster T aperture photometry results
table3.dat 113 1181 M31 star cluster C aperture photometry results
--------------------------------------------------------------------------------
See also:
J/ApJ/802/127 : PHAT stellar cluster survey. II. AP catalog (Johnson+, 2015)
J/A+A/602/A112 : M31 PHAT star clusters (de Meulenaer+, 2017)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- APID [1/6182] Cluster identification number
in PHAT, Johnson et al., 2015, J/ApJ/802/127
6- 15 F10.6 deg RAdeg Right ascension (J2000)
16- 25 F10.6 deg DEdeg Declination (J2000)
26- 30 F5.1 arcsec RT Radius of the Total (T) aperture
31- 35 F5.1 arcsec Rh Half-light radius in the passband F475W
36- 42 F7.3 mag F275W ? Total aperture magnitude in F275W
43- 49 F7.3 mag F336W Total aperture magnitude in F336W
50- 56 F7.3 mag F475W Total aperture magnitude in F475W
57- 63 F7.3 mag F814W Total aperture magnitude in F814W
64- 70 F7.3 mag F110W ? Total aperture magnitude in F110W
71- 77 F7.3 mag F160W ? Total aperture magnitude in F160W
78- 83 F6.3 mag e_F275W ? Error of the F275W magnitude
84- 89 F6.3 mag e_F336W Error of the F336W magnitude
90- 95 F6.3 mag e_F475W Error of the F475W magnitude
96-101 F6.3 mag e_F814W Error of the F814W magnitude
102-107 F6.3 mag e_F110W ? Error of the F110W magnitude
108-113 F6.3 mag e_F160W ? Error of the F160W magnitude
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- APID [1/6182] Cluster identification number in PHAT,
Johnson et al., 2015, J/ApJ/802/127
6- 15 F10.6 deg RAdeg Right ascension (J2000)
16- 25 F10.6 deg DEdeg Declination (J2000)
26- 30 F5.1 arcsec RT Radius of the Total (T) aperture
31- 35 F5.1 arcsec RC Radius of the Colour (C) aperture
36- 42 F7.3 mag F275W ? Colour aperture magnitude in F275W
43- 49 F7.3 mag F336W ? Colour aperture magnitude in F336W
50- 56 F7.3 mag F475W Colour aperture magnitude in F475W
57- 63 F7.3 mag F814W Colour aperture magnitude in F814W
64- 70 F7.3 mag F110W ? Colour aperture magnitude in F110W
71- 77 F7.3 mag F160W ? Colour aperture magnitude in F160W
78- 83 F6.3 mag e_F275W ? Error of the F275W magnitude
84- 89 F6.3 mag e_F336W ? Error of the F336W magnitude
90- 95 F6.3 mag e_F475W Error of the F475W magnitude
96-101 F6.3 mag e_F814W Error of the F814W magnitude
102-107 F6.3 mag e_F110W ? Error of the F110W magnitude
108-113 F6.3 mag e_F160W ? Error of the F160W magnitude
--------------------------------------------------------------------------------
Acknowledgements:
Vladas Vansevicius, wladasw(at)gmail.com
References:
de Meulenaer et al., Paper I 2013A&A...550A..20D 2013A&A...550A..20D
de Meulenaer et al., Paper II 2014A&A...569A...4D 2014A&A...569A...4D
de Meulenaer et al., Paper III 2015A&A...574A..66D 2015A&A...574A..66D
de Meulenaer et al., Paper IV 2015A&A...581A.111D 2015A&A...581A.111D
de Meulenaer et al., Paper V 2017A&A...602A.112D 2017A&A...602A.112D, Cat. J/A+A/602/A112
(End) Patricia Vannier [CDS] 27-Sep-2021