DESI Early Data Release Milky Way Survey value-added catalogue

International audienceWe present the stellar value-added catalogue based on the Dark Energy Spectroscopic Instrument (DESI) Early Data Release. The catalogue contains radial velocity and stellar parameter measurements for |$\simeq$| 400 000 unique stars observed during commissioning and survey validation by DESI. These observations were made under conditions similar to the Milky Way Survey (MWS) currently carried out by DESI but also include multiple specially targeted fields, such as those containing well-studied dwarf galaxies and stellar streams. The majority of observed stars have |$16\lt r\lt 20$| with a median signal-to-noise ratio in the spectra of |$\sim$| 20. In the paper, we describe the structure of the catalogue, give an overview of different target classes observed, as well as provide recipes for selecting clean stellar samples. We validate the catalogue using external high-resolution measurements and show that radial velocities, surface gravities, and iron abundances determined by DESI are accurate to 1 km s^−1, 0.3 dex, and |$\sim$| 0.15 dex respectively. We also demonstrate possible uses of the catalogue for chemo-dynamical studies of the Milky Way stellar halo and Draco dwarf spheroidal. The value-added catalogue described in this paper is the very first DESI MWS catalogue. The next DESI data release, expected in less than a year, will add the data from the first year of DESI survey operations and will contain approximately 4 million stars, along with significant processing improvements

DESI Early Data Release Milky Way Survey Value-Added Catalogue

We present the stellar value-added catalogue based on the Dark Energy Spectroscopic Instrument (DESI) Early Data Release. The catalogue contains radial velocity and stellar parameter measurements for $\simeq$ 400,000 unique stars observed during commissioning and survey validation by DESI. These observations were made under conditions similar to the Milky Way Survey (MWS) currently carried out by DESI but also include multiple specially targeted fields, such as those containing well-studied dwarf galaxies and stellar streams. The majority of observed stars have $16<r<20$ with a median signal-to-noise ratio in the spectra of $\sim$ 20. In the paper, we describe the structure of the catalogue, give an overview of different target classes observed, as well as provide recipes for selecting clean stellar samples. We validate the catalogue using external high-resolution measurements and show that radial velocities, surface gravities, and iron abundances determined by DESI are accurate to 1 km/s, $0.3$ dex and $\sim$ 0.15 dex respectively. We also demonstrate possible uses of the catalogue for chemo-dynamical studies of the Milky Way stellar halo and Draco dwarf spheroidal. The value-added catalogue described in this paper is the very first DESI MWS catalogue. The next DESI data release, expected in less than a year, will add the data from the first year of DESI survey operations and will contain approximately 4 million stars, along with significant processing improvements.Comment: Accepted to MNRAS; Value added catalogue is available at https://data.desi.lbl.gov/public/edr/vac/edr/mws/fuji

The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar and APOGEE-2 Data

This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library (MaStar) accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) survey which publicly releases infra-red spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the sub-survey Time Domain Spectroscopic Survey (TDSS) data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey (SPIDERS) sub-survey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated Value Added Catalogs (VACs). This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper (MWM), Local Volume Mapper (LVM) and Black Hole Mapper (BHM) surveys

The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar, and APOGEE-2 Data

This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys

Principles of Three Phase Capillary Pressures

Abstract In porous media, there are a variety of configurations in which three immiscible fluids can be distributed within a single body. For example, the fluids may be distributed as concentric rings. Alternatively, two fluids may be dispersed as separate blobs within the third fluid. The configuration governs the mobility of each fluid, and under equilibrium conditions is dictated by the three phase capillary pressure of the system. If the capillary pressure is altered, the configuration will change. Capillary pressure can be altered by flow of any phase through the pore body. However, in a three phase system flow cannot be described as simply "drainage" or "imbibition." Rather, flow must be described as "drainage/drainage," "drainage/imbibition: or "imbibition/imbibition" to account for the change in saturation of all three phases. This paper elaborates on the issues governing three phase capillary pressures and presents some first experimental results on oil/water/gas capillary pressures in a drainage/drainage mode. Literature Review Three phase capillary pressure data were first presented in a ternary plot format by Leverett(1). Details of how the data were obtained were not discussed. Another effort to present quantitative information on three phase capillary pressure systems was recently initiated in the field of hydrology. Lenhard and Parker(2) developed an experimental apparatus to directly measure monotonic capillary pressure curves for water/oil/air systems in unconsolidated media. Treated ceramic disks were used to create semi-permeable membranes for the free flow of water and oil from different ports. Direct measurements of water and total liquid saturations in three phase systems as functions of oil/water and air/oil capillary heads, respectively, were compared to saturation-pressure measurements in two-phase air/oil and oil/water systems for monotonic drainage saturation paths. Excellent agreement was observed between total liquid saturations in an air/oil/water system and oil saturations in an air/oil system as functions of air/oil capillary head. Excellent agreement was also found between water saturations in air/oil/water and oil/water fluid systems versus oil/water capillary head. The concept of three phase capillary pressures in enhanced oil recovery was recently revisited by Kantzas et al.(3,4) and Chatzis et al.(5) Three phase interactions (water/oil/gas) were evaluated in the course of investigating gravity assisted immiscible gas injection (GAIGI). Three phase capillary interactions were studied visually in regular geometry pores, but were not quantified. This was done by Kalaydjian(6) who performed both drainage and imbibition capillary pressure measurements using a multi porous membrane apparatus. Clashach sandstone cores were used. Measurements showed that both drainage and imbibition curves are dependent on the three saturations. This conclusion contradicts the results of Leverett as well as the hydrology models presented earlier. Kalaydjian(6) and Kalaydjian and Tixier(7) demonstrated the effect of the spreading coefficient on drainage capillary pressures (gas/oil) in the presence of connate water. It was found that the residual oil saturation was lower in the case of positive spreading coefficient than in the case of a negative one. Except for the low saturation values, the capillary pressure was higher in the case of a positive spreading coefficient than in the case of a negative one. </jats:sec