Final Targeting Strategy for the SDSS-IV APOGEE-2S Survey

Abstract APOGEE is a high-resolution (R ∼ 22,000), near-infrared, multi-epoch, spectroscopic survey of the Milky Way. The second generation of the APOGEE project, APOGEE-2, includes an expansion of the survey to the Southern Hemisphere called APOGEE-2S. This expansion enabled APOGEE to perform a fully panoramic mapping of all of the main regions of the Milky Way; in particular, by operating in the H band, APOGEE is uniquely able to probe the dust-hidden inner regions of the Milky Way that are best accessed from the Southern Hemisphere. In this paper we present the targeting strategy of APOGEE-2S, with special attention to documenting modifications to the original, previously published plan. The motivation for these changes is explained as well as an assessment of their effectiveness in achieving their intended scientific objective. In anticipation of this being the last paper detailing APOGEE targeting, we present an accounting of all such information complete through the end of the APOGEE-2S project; this includes several main survey programs dedicated to exploration of major stellar populations and regions of the Milky Way, as well as a full list of programs contributing to the APOGEE database through allocations of observing time by the Chilean National Time Allocation Committee and the Carnegie Institution for Science. This work was presented along with a companion article, Beaton et al. (2021), presenting the final target selection strategy adopted for APOGEE-2 in the Northern Hemisphere.

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Final Targeting Strategy for the Sloan Digital Sky Survey IV Apache Point Observatory Galactic Evolution Experiment 2 North Survey

The Astronomical Journal ◽

10.3847/1538-3881/ac260c ◽

2021 ◽

Vol 162 (6) ◽

pp. 302

Author(s):

Rachael L. Beaton ◽

Ryan J. Oelkers ◽

Christian R. Hayes ◽

Kevin R. Covey ◽

S. D. Chojnowski ◽

...

Keyword(s):

Near Infrared ◽

Survey Design ◽

Target Selection ◽

Lessons Learned ◽

Galactic Evolution ◽

Sloan Digital Sky Survey ◽

Scientific Success ◽

Sky Survey ◽

Evolution Experiment ◽

Targeting Strategy

Abstract The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is a dual-hemisphere, near-infrared (NIR), spectroscopic survey with the goal of producing a chemodynamical mapping of the Milky Way. The targeting for APOGEE-2 is complex and has evolved with time. In this paper, we present the updates and additions to the initial targeting strategy for APOGEE-2N presented in Zasowski et al. (2017). These modifications come in two implementation modes: (i) “Ancillary Science Programs” competitively awarded to Sloan Digital Sky Survey IV PIs through proposal calls in 2015 and 2017 for the pursuit of new scientific avenues outside the main survey, and (ii) an effective 1.5 yr expansion of the survey, known as the Bright Time Extension (BTX), made possible through accrued efficiency gains over the first years of the APOGEE-2N project. For the 23 distinct ancillary programs, we provide descriptions of the scientific aims, target selection, and how to identify these targets within the APOGEE-2 sample. The BTX permitted changes to the main survey strategy, the inclusion of new programs in response to scientific discoveries or to exploit major new data sets not available at the outset of the survey design, and expansions of existing programs to enhance their scientific success and reach. After describing the motivations, implementation, and assessment of these programs, we also leave a summary of lessons learned from nearly a decade of APOGEE-1 and APOGEE-2 survey operations. A companion paper, F. Santana et al. (submitted; AAS29036), provides a complementary presentation of targeting modifications relevant to APOGEE-2 operations in the Southern Hemisphere.

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Structure and dynamics of the Milky Way disk as revealed from the radial velocity distributions of APOGEE red clump stars

Proceedings of the International Astronomical Union ◽

10.1017/s174392131601173x ◽

2016 ◽

Vol 11 (S321) ◽

pp. 50-50

Author(s):

Daisuke Toyouchi ◽

Masashi Chiba

Keyword(s):

Near Infrared ◽

Milky Way ◽

Radial Velocities ◽

Galactocentric Distance ◽

Chemical Abundances ◽

Structure And Dynamics ◽

Evolution Experiment ◽

Dynamical Properties ◽

Red Clump ◽

Independent Work

AbstractWe investigate the structure and dynamics of the Milky Way (MW) disk stars based on the analysis of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) data, to infer the past evolution histories of the MW disk component(s) possibly affected by radial migration and/or satellite accretions. APOGEE is the first near-infrared spectroscopic survey for a large number of the MW disk stars, providing their radial velocities and chemical abundances without significant dust extinction effects. We here adopt red-clump (RC) stars (Bovy et al. 2014), for which the distances from the Sun are determined precisely, and analyze their radial velocities and chemical abundances in the MW disk regions covering from the Galactocentric distance, R, of 5 kpc to 14 kpc. We investigate their dynamical properties, such as mean rotational velocities, 〈Vφ〉 and velocity dispersions, as a function of R, based on the MCMC Bayesian method. We find that at all radii, the dynamics of alpha-poor stars, which are candidates of young disk stars, is much different from that of alpha-rich stars, which are candidates of old disk stars. We find that our Jeans analysis for our sample stars reveals characteristic spatial and dynamical properties of the MW disk, which are generally in agreement with the recent independent work by Bovy et al. (2015) but with a different method from ours.

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VVV DR1: The first data release of the Milky Way bulge and southern plane from the near-infrared ESO public survey VISTA variables in the Vía Láctea

Astronomy and Astrophysics ◽

10.1051/0004-6361/201118407 ◽

2012 ◽

Vol 537 ◽

pp. A107 ◽

Cited By ~ 232

Author(s):

R. K. Saito ◽

M. Hempel ◽

D. Minniti ◽

P. W. Lucas ◽

M. Rejkuba ◽

...

Keyword(s):

Near Infrared ◽

Milky Way ◽

Public Survey ◽

Data Release

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Effects of the selection function on metallicity trends in spectroscopic surveys of the Milky Way

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731099 ◽

2017 ◽

Vol 606 ◽

pp. A97 ◽

Cited By ~ 15

Author(s):

G. Nandakumar ◽

M. Schultheis ◽

M. Hayden ◽

A. Rojas-Arriagada ◽

G. Kordopatis ◽

...

Keyword(s):

Stellar Population ◽

Milky Way ◽

Target Selection ◽

Selection Function ◽

Population Synthesis ◽

Sample Distribution ◽

Stellar Population Synthesis ◽

Source Sample ◽

Correction Terms ◽

Metallicity Distribution

Context. Large spectroscopic Galactic surveys imply a selection function in the way they performed their target selection. Aims. We investigate here the effect of the selection function on the metallicity distribution function (MDF) and on the vertical metallicity gradient by studying similar lines of sight using four different spectroscopic surveys (APOGEE, LAMOST, RAVE, and Gaia-ESO), which have different targeting strategies and therefore different selection functions. Methods. We use common fields between the spectroscopic surveys of APOGEE, LAMOST, RAVE (ALR) and APOGEE, RAVE, Gaia-ESO (AGR) and use two stellar population synthesis models, GALAXIA and TRILEGAL, to create mock fields for each survey. We apply the selection function in the form of colour and magnitude cuts of the respective survey to the mock fields to replicate the observed source sample. We make a basic comparison between the models to check which best reproduces the observed sample distribution. We carry out a quantitative comparison between the synthetic MDF from the mock catalogues using both models to understand the effect of the selection function on the MDF and on the vertical metallicity gradient. Results. Using both models, we find a negligible effect of the selection function on the MDF for APOGEE, LAMOST, and RAVE. We find a negligible selection function effect on the vertical metallicity gradients as well, though GALAXIA and TRILEGAL have steeper and shallower slopes, respectively, than the observed gradient. After applying correction terms on the metallicities of RAVE and LAMOST with respect to our reference APOGEE sample, our observed vertical metallicity gradients between the four surveys are consistent within 1σ. We also find consistent gradient for the combined sample of all surveys in ALR and AGR. We estimated a mean vertical metallicity gradient of − 0.241 ± 0.028 dex kpc-1. There is a significant scatter in the estimated gradients in the literature, but our estimates are within their ranges. Conclusions. We have shown that there is a negligible selection function effect on the MDF and the vertical metallicity gradients for APOGEE, RAVE, and LAMOST using two stellar population synthesis models. Therefore, it is indeed possible to combine common fields of different surveys in studies using MDF and metallicity gradients provided their metallicities are brought to the same scale.

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City-Scale Distance Sensing via Bispectral Light Extinction in Bad Weather

Remote Sensing ◽

10.3390/rs12091401 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1401

Author(s):

Dong Zhao ◽

Yuta Asano ◽

Lin Gu ◽

Imari Sato ◽

Huixin Zhou

Keyword(s):

Extinction Coefficient ◽

Near Infrared ◽

Imaging System ◽

Weather Conditions ◽

Light Extinction ◽

Selection Strategy ◽

Infrared Wavelengths ◽

The Difference ◽

Bad Weather ◽

Almost All

In this paper, we propose a novel city-scale distance sensing algorithm based on atmosphere optics. The suspended particles, especially in bad weather, would attenuate the light at almost all wavelengths. Observing this fact and starting from the light scattering mechanism, we derive a bispectral distance sensing algorithm by leveraging the difference of extinction coefficient between two specifically selected near infrared wavelengths. The extinction coefficient of the atmosphere is related to both wavelength and meteorological conditions, also known as visibility, such as the fog and haze day. To account for different bad weather conditions, we explicitly introduce visibility into our algorithm by incorporating it into the calculation of extinction coefficient, making our algorithm simple yet effective. To capture the data, we build a bispectral imaging system that is able to take a pair of images with a monochrome camera and two narrow band-pass filters. We also present a wavelength selection strategy that allows us to accurately sense distance regardless of material reflectance and texture. Specifically, this strategy determines two distinct near infrared wavelengths by maximising the extinction coefficient difference while minimizing the influence of building’s reflectance variance. The experiments empirically validate our model and its practical performance on the distance sensing for the city-scale buildings.

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Multi-Wavelength Surveys for Galaxies Hidden by the Milky Way

International Astronomical Union Colloquium ◽

10.1017/s0252921100054178 ◽

1999 ◽

Vol 171 ◽

pp. 103-110 ◽

Cited By ~ 1

Author(s):

Renée C. Kraan-Korteweg

Keyword(s):

Near Infrared ◽

Milky Way ◽

Status Report ◽

Selection Effects ◽

Systematic Mapping ◽

Local Universe ◽

First Results ◽

Multi Wavelength ◽

Zone Of Avoidance

AbstractThe systematic mapping of obscured and optically invisible galaxies behind the Milky Way through complementary surveys are important in arriving at the whole-sky distribution of complete galaxy samples and therewith for our understanding of the dynamics in the local Universe. In this paper, a status report is given of the various deep optical, near infrared (NIR), and systematic blind H I-surveys in the Zone of Avoidance, including a discussion on the limitations and selection effects inherent to the different multi-wavelength surveys and first results.

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The origin of very massive stars around NGC 3603

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935107 ◽

2019 ◽

Vol 625 ◽

pp. L2 ◽

Cited By ~ 2

Author(s):

V. M. Kalari ◽

J. S. Vink ◽

W. J. de Wit ◽

N. J. Bastian ◽

R. A. Méndez

Keyword(s):

Near Infrared ◽

Milky Way ◽

Massive Stars ◽

Mass Function ◽

Initial Mass Function ◽

Future Data ◽

Solar Type ◽

Stellar Initial Mass Function ◽

The Universe ◽

Shed Light

The formation mechanism of the most massive stars in the Universe remains an unsolved problem. Are they able to form in relative isolation in a manner similar to the formation of solar-type stars, or do they necessarily require a clustered environment? In order to shed light on this important question, we study the origin of two very massive stars (VMS): the O2.5If*/WN6 star RFS7 (∼100 M⊙), and the O3.5If* star RFS8 (∼70 M⊙), found within ∼53 and 58 pc, respectively, of the Galactic massive young cluster NGC 3603, using Gaia data. The star RFS7 is found to exhibit motions resembling a runaway star from NGC 3603. This is now the most massive runaway star candidate known in the Milky Way. Although RFS8 also appears to move away from the cluster core, it has proper-motion values that appear inconsistent with being a runaway from NGC 3603 at the 3σ level (but with substantial uncertainties due to distance and age). Furthermore, no evidence for a bow-shock or a cluster was found surrounding RFS8 from available near-infrared photometry. In summary, whilst RFS7 is likely a runaway star from NGC 3603, making it the first VMS runaway in the Milky Way, RFS8 is an extremely young (∼2 Myr) VMS, which might also be a runaway, but this would need to be established from future spectroscopic and astrometric observations, as well as precise distances. If RFS 8 was still not found to meet the criteria for being a runaway from NGC 3603 from such future data, this would have important ramifications for current theories of massive star formation, as well as the way the stellar initial mass function is sampled.

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THE MILKY WAY PROJECT AND ATLASGAL: THE DISTRIBUTION AND PHYSICAL PROPERTIES OF COLD CLUMPS NEAR INFRARED BUBBLES

The Astrophysical Journal ◽

10.3847/0004-637x/825/2/142 ◽

2016 ◽

Vol 825 (2) ◽

pp. 142 ◽

Cited By ~ 14

Author(s):

Sarah Kendrew ◽

Henrik Beuther ◽

Robert Simpson ◽

Timea Csengeri ◽

Marion Wienen ◽

...

Keyword(s):

Physical Properties ◽

Near Infrared ◽

Milky Way

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A spectroscopic census of the Fornax cluster and beyond: preparing for next generation surveys

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2530 ◽

2019 ◽

Vol 490 (2) ◽

pp. 1666-1677 ◽

Cited By ~ 1

Author(s):

Natasha Maddox ◽

Paolo Serra ◽

Aku Venhola ◽

Reynier Peletier ◽

Ilani Loubser ◽

...

Keyword(s):

Dynamic System ◽

Southern Hemisphere ◽

Large Scale ◽

Near Infrared ◽

State Of The Art ◽

Large Scale Structure ◽

Large Cluster ◽

Cluster Membership ◽

The Many ◽

Fornax Cluster

ABSTRACT The Fornax cluster is the nearest large cluster in the southern sky, and is currently experiencing active assembly of mass. It is thus the target of a number of ongoing observing campaigns at optical, near-infrared, and radio wavelengths, using state-of-the-art facilities in the Southern hemisphere. Spectroscopic redshifts are essential not only for determining cluster membership, but also kinematics within the cluster and identifying substructures. We present a compilation of all available major spectroscopic campaigns undertaken within the Fornax region, including new and previously unpublished spectroscopy. This provides not only a comprehensive census of Fornax cluster membership as a resource for the many ongoing studies of this dynamic system, but also probes the large-scale structure in the background volume.

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The Nuclear Star Cluster of the Milky Way: Star Formation, Stellar Collisions and Central Dark Mass

Symposium - International Astronomical Union ◽

10.1017/s0074180900001418 ◽

1996 ◽

Vol 174 ◽

pp. 81-90

Author(s):

R. Genzel

Keyword(s):

Star Formation ◽

Near Infrared ◽

Milky Way ◽

Infrared Imaging ◽

Star Cluster ◽

Structure Evolution ◽

Late Type ◽

Massive Black Hole ◽

Imaging And Spectroscopy ◽

Central Parsec

High resolution near-infrared imaging and spectroscopy now gives detailed information about the structure, evolution and mass distribution in the nuclear star cluster of the Milky Way. The central parsec is powered by a cluster of luminous and helium rich, blue supergiants/Wolf-Rayet stars. The most likely scenario for the formation of the massive stars is a star formation burst a few million years ago at which time a dense gas cloud may have fallen into the center. The stellar density in the ∼ 0.3 pc radius central core is high enough that collisions with main sequence stars destroy the largest late type giant stars. Radial velocity measurements for about 300 early and late type stars between 0.1 and 5pc radius from the dynamic center now strongly favor the existence of a central dark mass of 2.5 − 3.3 × 106M⊙ (density (109M⊙pc−3, M/L2μm) ∼ 100M⊙/L⊙) within 0.1pc of the dynamic center. This central dark mass cannot be a cluster of neutron stars. It is either a compact cluster of stellar black holes or, most likely, a single massive black hole.

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