J/MNRAS/440/2036 VPHAS+ survey synthetic colours (Drew+, 2014)
The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge
(VPHAS+).
Drew J.E., Gonzalez-Solares E., Greimel R., Irwin M.J., Kupcu Yoldas A.,
Lewis J., Barentsen G., Eisloffel J., Farnhill H.J., Martin W.E.,
Walsh J.R., Walton N.A., Mohr-Smith M., Raddi R., Sale S.E., Wright N.J.,
Groot P., Barlow M.J., Corradi R.L.M., Drake J.J., Fabregat J., Frew D.J.,
Gansicke B.T., Knigge C., Mampaso A., Morris R.A.H., Naylor T.,
Parker Q.A., Phillipps S., Ruhland C., Steeghs D., Unruh Y.C., Vink J.S.,
Wesson R., Zijlstra A.A.
<Mon. Not. R. Astron. Soc., 440, 2036-3058 (2014)>
=2014MNRAS.440.2036D 2014MNRAS.440.2036D (SIMBAD/NED BibCode)
ADC_Keywords: Models ; Photometry, uvby ; Photometry, H-alpha
Keywords: surveys - stars: general - HII regions - planetary nebulae: general -
Galaxy: bulge - Galaxy: disc
Abstract:
The VST Photometric Hα Survey of the Southern Galactic Plane and
Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and
Hα at ∼1arcsec angular resolution. Its footprint spans the
Galactic latitude range -5°<b<+5° at all longitudes south of
the celestial equator. Extensions around the Galactic Centre to
Galactic latitudes ±10° bring in much of the Galactic bulge.
This European Southern Observatory public survey, begun on 2011
December 28, reaches down to ∼20th magnitude (10σ) and will
provide single-epoch digital optical photometry for ∼300 million
stars. The observing strategy and data pipelining are described, and
an appraisal of the segmented narrow-band Hα filter in use is
presented. Using model atmospheres and library spectra, we compute
main-sequence (u-g), (g-r), (r-i) and (r-Hα) stellar colours in
the Vega system. We report on a preliminary validation of the
photometry using test data obtained from two pointings overlapping the
Sloan Digital Sky Survey. An example of the (u-g, g-r) and
(r-Hα, r-i) diagrams for a full VPHAS+ survey field is given.
Attention is drawn to the opportunities for studies of compact nebulae
and nebular morphologies that arise from the image quality being
achieved. The value of the u band as the means to identify
planetary-nebula central stars is demonstrated by the discovery of the
central star of NGC 2899 in survey data. Thanks to its excellent
imaging performance, the VLT Survey Telescope (VST)/OmegaCam
combination used by this survey is a perfect vehicle for automated
searches for reddened early-type stars, and will allow the discovery
and analysis of compact binaries, white dwarfs and transient sources.
Description:
Synthetic colours for main sequence stars, computed as described in
Section 4 from model atmospheres, are here tabulated in full for three
representative reddening laws (RV = 2.5, 3.1 and 3.8) and a range of
reddenings (A0 = 0, 2, 4, 6, 8, 10). The form of the reddening laws
used is due to Fitzpatrick & Massa (2007ApJ...663..320F 2007ApJ...663..320F, Cat.
J/ApJ/663/320). When using the blue-filter tables, it should be borne
in mind that beyond g-r∼3, the red leak in the u filter signif-
icantly alters u-g. In this domain we expect the synthetic colours to
progressively become less reliable as they increas- ingly depend on
hard-to-measure very low levels of red trans- mission. Objects that
appear to have these extreme, peculiar colours are likely to be
reddened red giants or supergiants, since reddened K-M main sequence
stars are too faint to be detected in VPHAS+ exposures. Beyond g-r∼3.5
these table entries are italicised. Two further tables of synthetic
colours are included for K-M giants that have been computed using P98
library spectra. Data are provided for the RV=3.1 mean Galactic law
only, for the limited purposes of (a) giving an impres- sion of how
these luminous red objects may contaminate (u-g, g-r) diagrams at
redder (g-r) through u red leak (b) enabling comparisons with the
M-giant spur commonly seen in (r-Hα, r-i) colour-colour
diagrams.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 74 36 VST/OmegaCAM synthetic colours for main-sequence
stars in the (u-g), (g-r) plane reddened with
an RV=2.5 extinction law
tablea2.dat 74 36 VST/OmegaCAM synthetic colours for main-sequence
stars in the (u-g), (g-r) plane reddened with
an RV=3.1 extinction law
tablea3.dat 74 36 VST/OmegaCAM synthetic colours for main-sequence
stars in the (u-g), (g-r) plane reddened with
an RV=3.1 extinction law
tablea4.dat 83 36 VST/OmegaCAM synthetic colours for main-sequence
stars in the (r-i), (r-Hα) plane reddened
with an RV=2.5 extinction law
tablea5.dat 83 36 VST/OmegaCAM synthetic colours for main-sequence
stars in the (r-i), (r-Hα) plane reddened
with an RV=3.1 extinction law
tablea6.dat 83 36 VST/OmegaCAM synthetic colours for main-sequence
stars in the (r-i), (r-Hα) plane reddened
with an RV=3.8 extinction law
tablea7.dat 87 12 VST/OmegaCAM blue-filter colours synthesised
from P98 spectrophotometry for K-M giant stars,
reddened using an RV=3.1 extinction law
tablea8.dat 83 12 VST/OmegaCAM red-filter colours synthesised
from P98 spectrophotometry for K-M giant stars
reddened using an RV=3.1 extinction law
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See also:
J/ApJ/663/320 : IR-through-UV extinction curve (Fitzpatrick+, 2007)
Byte-by-byte Description of file: tablea[1237].dat
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Bytes Format Units Label Explanations
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1- 3 F3.1 --- RV RV value of extinction law (G1)
5- 9 A5 --- SpType Spectral type
11- 16 F6.3 mag (u-g)0 u-g colour index for A0=0 range of reddening
18- 23 F6.3 mag (g-r)0 g-r colour index for A0=0 range of reddening
25- 30 F6.3 mag (u-g)2 u-g colour index for A0=2 range of reddening
32- 36 F5.3 mag (g-r)2 g-r colour index for A0=2 range of reddening
38- 43 F6.3 mag (u-g)4 u-g colour index for A0=4 range of reddening
45- 49 F5.3 mag (g-r)4 g-r colour index for A0=4 range of reddening
51- 55 F5.3 mag (u-g)6 u-g colour index for A0=6 range of reddening
57- 61 F5.3 mag (g-r)6 g-r colour index for A0=6 range of reddening
63- 68 F6.3 mag (u-g)8 u-g colour index for A0=8 range of reddening
70- 74 F5.3 mag (g-r)8 g-r colour index for A0=8 range of reddening
76- 81 F6.3 mag (u-g)10 ? u-g colour index for A0=10 range of
reddening (tablea7 only)
83- 87 F5.3 mag (g-r)10 ? g-r colour index for A0=10 range of
reddening (tablea7 only)
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Byte-by-byte Description of file: tablea[4568].dat
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Bytes Format Units Label Explanations
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1- 3 F3.1 --- RV RV value of extinction law (G1)
5- 9 A5 --- SpType Spectral type
11- 16 F6.3 mag (r-i)0 r-i colour index for A0=0 range of reddening
18- 23 F6.3 mag (r-Ha)0 r-Ha colour index for A0=0 range of reddening
25- 29 F5.3 mag (r-i)2 r-i colour index for A0=2 range of reddening
31- 35 F5.3 mag (r-Ha)2 r-Ha colour index for A0=2 range of reddening
37- 41 F5.3 mag (r-i)4 r-i colour index for A0=4 range of reddening
43- 47 F5.3 mag (r-Ha)4 r-Ha colour index for A0=4 range of reddening
49- 53 F5.3 mag (r-i)6 r-i colour index for A0=6 range of reddening
55- 59 F5.3 mag (r-Ha)6 r-Ha colour index for A0=6 range of reddening
61- 65 F5.3 mag (r-i)8 r-i colour index for A0=8 range of reddening
67- 71 F5.3 mag (r-Ha)8 r-Ha colour index for A0=8 range of reddening
73- 77 F5.3 mag (r-i)10 r-i colour index for A0=10 range of reddening
79- 83 F5.3 mag (r-Ha)10 r-Ha colour index for A0=108 range of reddening
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Global notes:
Note (G1): RV is the ratio of reddening to extinction at V.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 31-Jul-2015