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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 (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; 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:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 153 8 List of fits files fits/* 0 8 Individual fits files
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
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
History: From Francisco Nogueras-Lara, fnoguer(at) 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
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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