CASIS: Cassegrain Adaptive-Optics Simultaneous Imaging System for the VLT

Kissler-Patig, M.; Casali, M.; Délabre, Bernard; Hubin, N.; Käufl, H. U.; Jolley, Paul; Louarn, Miska Le; Oberti, Sylvain; Pirard, Jean-François

doi:10.1007/978-1-4020-9190-2_85

Cited by 49 publications

(56 citation statements)

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“…The total integration time of each observation is given by N × NDIT × DIT. Kissler-Patig et al 2008) located at the ESO Very Large Telescope (VLT) unit telescope 4, using the broadband filters J, H, and K s . HAWK-I has a field of view (FOV) of 7 .5 × 7 .5 with a cross-shaped gap of 15 between its four Hawaii-2RG detectors.…”

Section: Observationsmentioning

confidence: 99%

GALACTICNUCLEUS: A high angular resolutionJHK_simaging survey of the Galactic centre

Nogueras-Lara¹,

Gallego-Calvente²,

Dong³

et al. 2018

A&A

176

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Context. The Galactic centre (GC) 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. Aims. 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′ × 3.43′. 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. Methods. The data were acquired with the near-infrared camera High Acuity Wide field K-band Imager (HAWK-I) at the ESO Very Large Telescope (VLT). 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 VISTA Variables in the Via Lactea (VVV) survey and photometric calibration is based on the SIRIUS/Infrared Survey Facility telescope (IRSF) 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. Results. We reach 5σ detection limits of approximately J = 22, H = 21, and Ks = 20. The photometric 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 GC. 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 αJHKs = 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 GC. 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.

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Section: Observationsmentioning

confidence: 99%

GALACTICNUCLEUS: A high angular resolutionJHK_simaging survey of the Galactic centre

Nogueras-Lara¹,

Gallego-Calvente²,

Dong³

et al. 2018

A&A

176

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“…This work makes use of the GALACTICNUCLEUS survey (Nogueras-Lara et al 2018a, 2019a carried out using the HAWK-I camera (Kissler-Patig et al 2008) at the ESO VLT unit telescope 4, which includes accurate JHK s photometry of more than 3.3 million stars located in the GC and inner regions of the Galactic bulge. Figure 1 shows the fields included in the GALACTICNUCLEUS survey: three different regions distributed along the GC (Central, NSD East, and NSD West), two regions in the inner Galactic bulge (inner bulge South and inner bulge North), and two transition regions (transition East and West).…”

Section: Datamentioning

confidence: 99%

GALACTICNUCLEUS: A high angular-resolution JHK_s imaging survey of the Galactic centre

Nogueras-Lara

Schödel

Neumayer

et al. 2020

A&A

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Context. The characterisation of the extinction curve in the near-infrared (NIR) is fundamental to analysing the structure and stellar population of the Galactic centre (GC), whose analysis is hampered by the extreme interstellar extinction (AV ~ 30 mag) that varies on arc-second scales. Recent studies indicate that the behaviour of the extinction curve might be more complex than previously assumed, pointing towards a variation of the extinction curve as a function of wavelength. Aims. We aim to analyse the variations of the extinction index, α, with wavelength, line-of-sight, and absolute extinction, extending previous analyses to a larger area of the innermost regions of the Galaxy. Methods. We analysed the whole GALACTICNUCLEUS survey, a high-angular resolution (~0.2″) JHKs NIR survey specially designed to observe the GC in unprecedented detail. It covers a region of ~6000 pc2, comprising fields in the nuclear stellar disc, the inner bulge, and the transition region between them. We applied two independent methods based on red clump (RC) stars to constrain the extinction curve and analysed its variation superseding previous studies. Results. We used more than 165 000 RC stars and increased the size of the regions analysed significantly to confirm that the extinction curve varies with the wavelength. We estimated a difference Δα = 0.21 ± 0.07 between the obtained extinction indices, αJH = 2.44 ± 0.05 and αHKs = 2.23 ± 0.05. We also concluded that there is no significant variation of the extinction curve with wavelength, with the line-of-sight or the absolute extinction. Finally, we computed the ratios between extinctions, AJ∕AH = 1.87 ± 0.03 and AH/AKs = 1.84 ± 0.03, consistent with all the regions of the GALACTICNUCLEUS catalogue.

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“…1). The observations were carried out with HAWK-I (High Wide field K-band Imager, Kissler-Patig et al 2008) located at the ESO VLT unit telescope 4 1 . We used the broadband filters J, H and K s to cover the NIR regime.…”

Section: Observationsmentioning

confidence: 99%

GALACTICNUCLEUS: A high-angular-resolution JHK_s imaging survey of the Galactic centre

Nogueras-Lara

Schödel

Gallego-Calvente

et al. 2019

A&A

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Context. The high extinction and extreme source crowding of the central regions of the Milky Way are serious obstacles to the study of the structure and stellar population of the Galactic centre (GC). Existing surveys that cover the GC region (2MASS, UKIDSS, VVV, SIRIUS) do not have the necessary high angular resolution. Therefore, a high-angular-resolution survey in the near infrared is crucial to improve the state of the art. Aims. Here, we present the GALACTICNUCLEUS catalogue, a near infrared JHKs high-angular-resolution (0.2″) survey of the nuclear bulge of the Milky Way. Methods. We explain in detail the data reduction, data analysis, calibration, and uncertainty estimation of the GALACTICNUCLEUS survey. We assess the data quality comparing our results with previous surveys. Results. We obtained accurate JHKs photometry for ∼3.3 × 106 stars in the GC detecting around 20% in J, 65% in H, and 90% in Ks. The survey covers a total area of ∼0.3 deg2, which corresponds to ∼6000 pc2. The GALACTICNUCLEUS survey reaches 5σ detections for J ∼ 22 mag, H ∼ 21 mag, and Ks ∼ 21 mag. The uncertainties are below 0.05 mag at J ∼ 21 mag, H ∼ 19 mag, and Ks ∼ 18 mag. The zero point systematic uncertainty is ≲0.04 mag in all three bands. We present colour–magnitude diagrams for the different regions covered by the survey.

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CASIS: Cassegrain Adaptive-Optics Simultaneous Imaging System for the VLT

Cited by 49 publications

References 1 publication

GALACTICNUCLEUS: A high angular resolutionJHK_simaging survey of the Galactic centre

GALACTICNUCLEUS: A high angular resolutionJHK_simaging survey of the Galactic centre

GALACTICNUCLEUS: A high angular-resolution JHK_s imaging survey of the Galactic centre

GALACTICNUCLEUS: A high-angular-resolution JHK_s imaging survey of the Galactic centre

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CASIS: Cassegrain Adaptive-Optics Simultaneous Imaging System for the VLT

Cited by 49 publications

References 1 publication

GALACTICNUCLEUS: A high angular resolutionJHKsimaging survey of the Galactic centre

GALACTICNUCLEUS: A high angular resolutionJHKsimaging survey of the Galactic centre

GALACTICNUCLEUS: A high angular-resolution JHKs imaging survey of the Galactic centre

GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre

Contact Info

Product

Resources

About

GALACTICNUCLEUS: A high angular resolutionJHK_simaging survey of the Galactic centre

GALACTICNUCLEUS: A high angular resolutionJHK_simaging survey of the Galactic centre

GALACTICNUCLEUS: A high angular-resolution JHK_s imaging survey of the Galactic centre

GALACTICNUCLEUS: A high-angular-resolution JHK_s imaging survey of the Galactic centre