J/other/PASA/26.439 K-band images of star-forming regions (Longmore+, 2009)
Ks-band, 2.14-um imaging of southern massive star formation regions traced by
methanol masers.
Longmore S.N., Burton M.G.
<Publ. Astron. Soc. Australia, 26, 439-447 (2009)>
=2009PASA...26..439L 2009PASA...26..439L
ADC_Keywords: Infrared sources ; Masers ; Photometry, infrared ;
Stars, early-type ; YSOs
Keywords: Galaxy: stellar content - masers - infrared: stars -
stars: early type - stars: formation
Abstract:
We present deep, wide-field, Ks-band (2.14-micron) images towards 87
southern massive star formation regions traced by methanol maser
emission. Using point-spread function fitting, we generate 2.14-micron
point source catalogues (PSCs) towards each of the regions. For the
regions between 10°<l<350° and |b|<1, we match the 2.14-micron
sources with the GLIMPSE point source catalogue to generate a combined
2.14- to 8.0-micron point source catalogue. We provide this data for
the astronomical community to utilise in studies of the stellar
content of embedded clusters.
Description:
For the 87 regions observed, this catalog provides i) 2.14 micron,
IRIS2 flux-calibrated fits images, ii) a text file listing the
positions, magnitude and magnitude uncertainties of all Ks-band point
sources extracted via PSF fitting, and iii) a text file of Ks-band
sources matched with those in the GLIMPSE catalog listing the
photometry from 2.14 to 8.0 microns.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 117 87 Summary of the data characteristics for each of
the regions observed with IRIS2
ks_cat.dat 34 959183 *Position and photometry of Ks-band sources
comb_cat.dat 111 90817 *Combined IRIS2 and GLIMPSE catalog
fits/* . 86 Flux-calibrated fits files
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Note on comb_cat.dat: IRIS2 Ks-band sources in ks_cat.dat matched with
sources in the GLIMPSE PSC.
Note on ks_cat.dat: Ks-band sources in the IRIS2 images identified using
automated point source fitting and photometry.
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See also:
J/MNRAS/380/1497 : JHKs+GLIMPSE photometry towards G305.2+0.2 (Longmore+ 2007)
Description of file: fits/*
A single fits file is provided for each region. The names and target
positions are reported in columns 1 to 4 of table1.dat. The magnitude,
m, of a source can be calculated using the zero-point magnitude (given
by the MAGZERO keyword in each fits header), mZP, which corresponds to
the magnitude of a source in the image with a flux count of 1.
A source with flux count, f, has a magnitude given by: m=mZP-2.5logf.
The field of view of each image is 9.7'x9.7'. However, the 9-point
mosaiking pattern means only the inner 5.7'x5.7' are covered by all 9
coaddded frames. A typical sensitivity in the inner region of an
uncrowded field for IRIS2 would be ∼19.6mag (5sigma) in good
conditions. The image properties towards each region (including
sensitivities, completeness, seeing and number of sources) determined
from PSF fitting are listed in table1.dat.
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Region Galactic name of the far-IR sources whose
fields have been imaged (GLLL.ll+B.bb) (1)
13 A1 --- n_Region [b] Image previously published (1)
15- 27 A13 --- IRAS IRAS name of the far-IR sources whose fields
have been imaged (2)
28- 29 I2 h RAh Right ascension (J2000) (2)
31- 32 I2 min RAm Right ascension (J2000) (2)
34- 37 F4.1 s RAs Right ascension (J2000) (2)
39 A1 --- DE- Declination sign (J2000) (2)
40- 41 I2 deg DEd Declination (J2000) (2)
43- 44 I2 arcmin DEm Declination (J2000) (2)
46- 49 F4.1 arcsec DEs Declination (J2000) (2)
51- 54 F4.2 mag e_ZPmag Standard deviation of the difference between
the measured IRIS2 and 2MASS magnitudes
(in the range 10-12mag)
56- 60 F5.2 mag ZPmag Zero-point magnitude (3)
62- 64 F3.1 mag min Minimum magnitude of sources in region
66- 69 F4.1 mag med Median magnitude of sources in region
71- 74 F4.1 mag max Maximum magnitude of sources in region
76- 79 F4.2 mag e_med Median point-source fitting error in region
81- 84 F4.1 mag min1 Minimum reliable IRIS2 magnitude (4)
86- 89 F4.1 mag m90 90% completeness magnitude estimated from the
magnitude histogram
91- 95 I5 --- N Total number of sources detected in IRIS2 field
97-100 F4.2 arcsec FWHM FWHM of the seeing
102-117 A16 --- FITSfile Name of the fits file in subdirectory fits (1)
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Note (1): Region names and FITS file names follow the pattern "GLLL.ll+B.bb",
i.e. the longitude part contains appropriate number of leading zeroes
to fit the pattern, e.g. G001.15-0.12 is used rather than G1.15-0.12.
The region G305.20+0.21 has been included in this table for
completeness but the catalogue and images can be found in Longmore
et al. (2007, Cat. J/MNRAS/380/1497).
Note (2): Position of the associated methanol masers from Walsh et al.
(1998, Cat. J/MNRAS/301/640).
Note (3): MAGZERO, which gives the magnitude in each image corresponding to
a flux count of 1, i.e. m=mZP-2.5logf, where f is the number of counts
determined for a source of interest in the FITS images
Note (4): Corresponding to the maximum flux per field over which the array
responded linearly. Sources brighter than which are likely to be
affected by saturation.
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Byte-by-byte Description of file: ks_cat.dat
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Bytes Format Units Label Explanations
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1- 8 F8.4 deg RAdeg Right ascension in decimal degrees (J2000) (1)
10- 19 F10.6 deg DEdeg Declination in decimal degrees (J2000) (1)
21- 28 F8.5 mag Ksmag Ks-band magnitude (G1)
30- 34 F5.3 mag e_Ksmag Ks-band magnitude uncertainty (G2)
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Note (1): Sources identified as [LB2009] DDD.dddd+DD.dddd in Simbad.
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Byte-by-byte Description of file: comb_cat.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- --- [SSTGLMC_]
9- 25 A17 --- GLIMPSE Glimpse ID, GLLL.llll+BB.bbbb (1)
27- 34 F8.4 deg RAdeg Right ascension in decimal degrees (J2000) (2)
36- 45 F10.6 deg DEdeg Declination in decimal degrees (J2000) (1)
47- 53 F7.4 mag Ksmag Ks-band magnitude (G1)
55- 59 F5.3 mag e_Ksmag Ks-band magnitude uncertainty (G2)
61- 66 F6.3 mag [3.6] ?=- 3.6 micron magnitude (3)
68- 72 F5.3 mag e_[3.6] ?=- 3.6 micron magnitude uncertainty (3)
74- 79 F6.3 mag [4.5] ?=- 4.5 micron magnitude (3)
81- 85 F5.3 mag e_[4.5] ?=- 4.5 micron magnitude uncertainty (3)
87- 92 F6.3 mag [5.8] ?=- 5.8 micron magnitude (3)
94- 98 F5.3 mag e_[5.8] ?=- 5.8 micron magnitude uncertainty (3)
100-105 F6.3 mag [8.0] ?=- 8.0 micron magnitude (3)
107-111 F5.3 mag e_[8.0] ?=- 8.0 micron magnitude uncertainty (3)
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Note (1): ID from the GLIMPSE point-source catalog (see
http://www.astro.wisc.edu/sirtf/ and Benjamin et al.,
2003PASP..115..953B 2003PASP..115..953B for details).
Note (2): The assumed astrometric uncertainty between the PSCs was taken as
0.3", the uncertainty in 2MASS astrometry. However, as both IRIS2 and
GLIMPSE used 2MASS for absolute coordinate reference positions, their
relative astrometric uncertainty should be much smaller than this.
Using synthetic data sets to test the matching algorithms, we expect
to recover 99.8% of the sources correctly with a maximum of 0.1%
multiply-matched and 0.12% mismatched sources.
Note (3): See http://www.astro.wisc.edu/sirtf/ and Benjamin et al.,
2003PASP..115..953B 2003PASP..115..953B for details.
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Global notes:
Note (G1): The photometry was calibrated using sources between ∼12th and
14th magnitude in the 2MASS catalogue which were bright but not
saturated in the IRIS2 images.
Note (G2): The reported uncertainty is the statistical error from the
photometric fitting.
Systematic uncertainties were estimated using the scatter between the
2MASS and IRIS2 magnitudes after flux calibration (∼0.13mag averaged
over all the fields - approximately twice the photometric fitting
error). The value for each field is reported in column 5 of Table 1 in
LB09. Some of this scatter is likely due to the difference between the
IRIS2/2MASS photometric system. Although converting to the 2MASS
photometric system may marginally reduce this scatter, the colour
correction terms are not characterised for the very red, likely
heavily embedded sources of interest in star formation studies.
Depending on the field, IRIS2 sources brighter than ∼11th magnitude
suffer from saturation. Column "Minrel" in table1.dat gives the
minimum reliable magnitude for each region, corresponding to the
maximum flux per field over which the array responded linearly.
Photometry for stars brighter than this should be taken from the 2MASS
catalogue.
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Acknowledgements:
Steve Longmore, slongmore(at)cfa.harvard.edu
(End) Patricia Vannier [CDS] 26-Nov-2009