J/A+A/610/A83 GALACTICNUCLEUS: JHKs imaging survey (Nogueras-Lara+, 2018)
GALACTICNUCLEUS: A high angular resolution JHKs imaging survey of the Galactic
Centre. I. Methodology, performance, and near-infrared extinction towards the
Galactic Centre.
Nogueras-Lara F., Gallego-Calvente A.T., Dong H., Gallego-Cano E.,
Girard J.H.V., Hilker M., de Zeeuw P.T., Feldmeier-Krause A., Nishiyama S.,
Najarro F., Neumayer N., Schoedel R.
<Astron. Astrophys. 610, A83 (2018)>
=2018A&A...610A..83N 2018A&A...610A..83N (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Galactic center ; Photometry, infrared ; Extinction
Keywords: Galaxy: nucleus - dust, extinction - Galaxy: centre -
stars: horizontal-branch
Abstract:
The Galactic Centre is of fundamental astrophysical interest, but
existing near-infrared surveys fall short covering it adequately,
either in terms of angular resolution, multi-wavelength coverage, or
both. Here we introduce the GALACTICNUCLEUS survey, a JHKs imaging
survey of the centre of the Milky Way with a 0.2" angular
resolution. The purpose of this paper is to present the observations
of Field 1 of our survey, centred approximately on SgrA* with an
approximate size of 7.95'x3.43'. We describe the observational
set-up and data reduction pipeline and discuss the quality of the
data. Finally, we present the analysis of the data. The data were
acquired with the near-infrared camera HAWK-I (High Acuity Wide field
K-band Imager) at the ESO VLT (Very Large Telescope). Short readout
times in combination with the speckle holography algorithm allowed us
to produce final images with a stable, Gaussian PSF (point spread
function) of 0.2" FWHM (full width at half maximum). Astrometric
calibration is achieved via the VVV (VISTA Variables in the Via
Lactea) survey and photometric calibration is based on the SIRIUS/IRSF
(Infrared Survey Facility telescope) survey. The quality of the data
is assessed by comparison between observations of the same field with
different detectors of HAWK-I and at different times. We reach
5σ uncertainties are less than 0.05" at J≤20, H≤17, and
Ks≤16. We can distinguish five stellar populations in the
colour-magnitude diagrams; three of them appear to belong to
foreground spiral arms, and the other two correspond to high- and
low-extinction star groups at the Galactic Centre. We use our data to
analyse the near-infrared extinction curve and find some evidence for
a possible difference between the extinction index between J-H and
H-Ks. However, we conclude that it can be described very well by a
power law with an index of JHKs=2.30+.-0.08. We do not find any
evidence that this index depends on the position along the line of
sight, or on the absolute value of the extinction. We produce
extinction maps that show the clumpiness of the ISM (interstellar
medium) at the Galactic Centre. Finally, we estimate that the majority
of the stars have solar or super-solar metallicity by comparing our
extinction-corrected colour-magnitude diagrams with isochrones with
different metallicities and a synthetic stellar model with a constant
star formation.
Description:
We include in electronic form the Ks extinction maps and the
corresponding uncertainty maps presented in the manuscript in Section
7. They correspond to Figs. 28, 30 and 31. The units in all the cases
are Ks magnitudes. All the images are astrometrically calibrated
following the procedure described in the main text (Sec. 3).
Files are named AK + ("u" if the map is an uncertainty map) + _ +
associated number of figure in the main text + ("a" or "b"
meaning upper and lower panel in the corresponding figure,
respectively) + .fit
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 153 8 List of fits files
fits/* . 8 Individual fits files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 25 F6.4 arcsec/pix Scale Scale of the image
27- 30 I4 --- Nx Number of pixels along X-axis
32- 35 I4 --- Ny Number of pixels along Y-axis
37- 42 I6 Kibyte size Size of FITS file
44- 54 A11 --- FileName Name of FITS file, in subdirectory fits
56-153 A98 --- Title Title of the FITS file
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History:
From Francisco Nogueras-Lara, fnoguer(at)iaa.es
Acknowledgements:
The research leading to these results has received funding from the
European Research Council under the European Union's Seventh
Framework Programme (FP7/2007-2013) / ERC grant agreement No [614922].
This work is based on observations made with ESO Telescopes at the La
Silla Paranal Observatory under programmes IDs 195.B-0283 and
091.B-0418. We thank the staff of ESO for their great efforts and
helpfulness. F N-L acknowledges financial support from a MECD
pre-doctoral contract, code FPU14/01700. F N acknowledges Spanish
grants FIS2012-39162-C06-01, ESP2013-47809-C3-1-R and
ESP2015-65597-C4-1-R. This work has made use of the IAC-STAR Synthetic
CMD computation code. IAC-STAR is supported and maintained by the
computer division of the Instituto de Astrofisica de Canarias.
(End) F. Nogueras-Lara [IAA-CSIC, Spain], P. Vannier [CDS] 30-Nov-2017