The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA Derived Quantities, Data Visualization Tools and Stellar Library

Abstract: Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (July 2014-July 2017). This is the third data release for SDSS-IV, and the fifteenth from SDSS (Data Release Fifteen; DR15). New data come from MaNGA - we release 4824 datacubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g. stellar and gas kinematics, emission line, and other maps) from the MaNGA Data Analysis Pipeline (DAP), and a new data visualisation and access tool we call "Marvin". The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials and examples of data use. While SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020-2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data.

• The paper presents the first release of MaNGA-derived quantities, including 4824 datacubes with stellar kinematics and gas properties.
• It details advanced data reduction pipelines with improved flux calibration, line-spread function estimation, and spectral covariance handling.
• It introduces Marvin, a novel visualization tool that streamlines querying and analysis of complex 3D astronomical data.

Summary of "The Fifteenth Data Release of the Sloan Digital Sky Surveys"

The paper "The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA Derived Quantities, Data Visualization Tools and Stellar Library" presents the fifteenth data release (DR15) from the Sloan Digital Sky Survey (SDSS). This release, part of the fourth phase of SDSS (SDSS-IV), is notable for several key new data products and updates stemming from its sub-programs, particularly the MaNGA survey. The document comprehensively outlines the contents of DR15, the methodologies of the data processing, and the application tools developed to facilitate the access and interpretation of this data.

MaNGA Highlights

A significant feature of DR15 is the inclusion of 4824 datacubes from the Mapping Nearby Galaxies at APO (MaNGA) survey. This dataset extends the observations from the first three years of SDSS-IV operations (July 2014–July 2017). For the first time, DR15 includes derived quantities like stellar kinematics, gas properties, and other survey-supported analyses from the MaNGA Data Analysis Pipeline (DAP). Additionally, DR15 introduces the MaNGA Stellar Library (MaStar), which provides an empirical spectral library that aims to cover stellar parameter space more comprehensively than previous libraries.

Data Visualization and Access

The release introduces "Marvin," a new tool designed for the visualization and analysis of MaNGA datasets. Marvin addresses the inherent complexity of MaNGA's three-dimensional data structure, allowing researchers to query, access, and analyze data efficiently, either through a webpage tool or a programmatic Python interface. This tool is integral for handling the extensive datasets produced by the MaNGA survey and enhances the usability of spectroscopic data cubes by providing streamlined access and visualization capabilities.

Pipeline Enhancements

DR15 reports enhancements in data reduction and processing pipelines. Notable improvements include adaptations to flux calibration utilizing updated stellar models, enhanced estimation of line-spread function, and better management of spectral covariance during data cube assembly. The data reduction and analysis protocols have been revised iteratively to improve the fidelity and scientific value of resultant data products.

Other Programs

While the primary focus of DR15 is MaNGA, the release also provides updates on other SDSS initiatives such as APOGEE-2, which continues to explore the infrared spectroscopic characteristics of diverse stellar populations, with a focus on high-resolution spectra. Although DR15 does not include new APOGEE-2 data, it highlights refinements to existing data and analytical methods.

Additionally, the extended Baryon Oscillation Spectroscopic Survey (eBOSS) contributes further to LSS studies by focusing on cosmological samples of luminous red galaxies and quasars, a framework that allows continued exploration of large scale structure and further cosmological constraints.

Implications and Future Directions

The data accessible through DR15 is set to impact broad areas of astrophysics — from understanding the formation and dynamics of galaxies, the properties of stars throughout the Milky Way, to refining cosmological models based on large-scale structure surveys. The continued development pipeline improvements and research tools fortify SDSS's role in astronomical data provision.

Future steps for SDSS-IV and impending SDSS-V are set to further expand the volume and diversity of astronomical datasets. DR16 will serve as an endpoint for new eBOSS datasets, while the anticipated SDSS-V is set to introduce even greater observational capabilities and thematic research areas, encompassing both galactic and extragalactic phenomena.

In conclusion, DR15 of the SDSS collections marks a significant advancement in the accessibility and utility of astronomical data, reflecting continuous refinement of data gathering, analysis pipelines, and public dissemination strategies, providing the scientific community with the resources needed to tackle both current and emerging questions in astrophysics.