ner_tags: O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O B-ObservationalTechniques I-ObservationalTechniques B-ObservationalTechniques O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O B-Survey I-Survey B-Citation I-Citation I-Citation I-Citation O O O O O O O O B-Survey O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation O O O O O B-Citation I-Citation I-Citation I-Citation O O O B-Citation I-Citation I-Citation I-Citation O O O O O B-Telescope I-Telescope I-Telescope O B-Telescope B-Instrument I-Instrument I-Instrument I-Instrument B-Instrument O O O O O O B-Citation I-Citation I-Citation I-Citation O O O B-Telescope I-Telescope B-Telescope B-Wavelength I-Wavelength O O O O O O O O B-Survey O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O B-Wavelength I-Wavelength O O O B-Wavelength O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O B-Survey I-Survey I-Survey I-Survey B-Survey B-Citation I-Citation I-Citation I-Citation O B-Dataset I-Dataset I-Dataset B-Dataset B-Citation I-Citation I-Citation I-Citation O O O O O O B-Dataset I-Dataset I-Dataset I-Dataset I-Dataset O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation O B-Citation I-Citation O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O B-ObservationalTechniques O O O O O O O O O O O O O O B-Wavelength O O O O O B-Instrument I-Instrument O O B-Observatory I-Observatory B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O B-Software B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O B-Survey I-Survey O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O
tokens: at radial gradients in stellar populations have worked within R e (e.g., Spinrad Taylor 1971 ; Mehlert et al. 2003 ; Annibali et al. 2007 ; Spolaor et al. 2010 ; Jimmy et al. 2013 ; McDermid et al. 2015 ; Goddard et al. 2017 ). In recent years, integral-field spectroscopy (IFS) has enabled stellar population measurements at a large radius (e.g., Greene et al. 2013 , 2015 ; Scott et al. 2013 ; McDermid et al. 2015 ; Boardman et al. 2017 ; Goddard et al. 2017 ; Barone et al. 2018 ; van de Sande et al. 2018 ). Here, we focus on the most massive galaxies in the present-day universe using the MASSIVE survey (Ma et al. 2014 ). We have gathered integral-field data for 90 MASSIVE galaxies and measured their stellar kinematics, including higher-order moments (Veale et al. 2017a , 2017b ), stellar velocity dispersion profiles (Veale et al. 2018 ), and kinemetry (Ene et al. 2018 ). In addition, we have Hubble Space Telescope ( HST )/Wide Field Camera 3 (WFC3) imaging for 30 of the galaxies (Goullaud et al. 2018 ) and uniform Canada–France–Hawai’i Telescope (CFHT) K -band imaging for nearly all objects. 2. Galaxy Sample MASSIVE is a volume-limited survey of 116 galaxies (see details in Veale et al. 2017b ) in the northern hemisphere within D 108 Mpc (i.e., to the distance of the Coma cluster), with K -band magnitudes of M K −25.3 mag (roughly > 10 11.5 M ⊙ ). Details of the target selection are described in Ma et al. ( 2014 ). Briefly, our targets are drawn from the Two Micron All-sky Survey (2MASS; Skrutskie et al. 2006 ) Extended Source Catalog (XSC; Jarrett et al. 2003 ) combined with distances from the high-density contrast (HDC) group catalog from Crook et al. ( 2007 ), supplemented by surface brightness fluctuations when available (Blakeslee et al. 2009 , 2010 ; Blakeslee 2013 ) and with the flow model of Mould et al. ( 2000 ) when needed. We have completed IFS observations for 90 galaxies, including complete coverage of the 75 galaxies that have M K −25.5 mag. We use the Mitchell IFS at the McDonald Observatory (Hill et al. 2008 ), which has a 107 × 107 arcsec 2 field of view, one-third of which is filled by 246 fibers of a 4′′ diameter. Each galaxy is observed at three dither positions with 20-minute exposures, interspersed with 10-minute sky observations. The spectra span 3650–5850 Å, with a spectral resolution of 4.5 Å FWHM. The data are reduced using the custom software Vaccine (Adams et al. 2011 ; Murphy et al. 2011 ). For more details, see Greene et al. ( 2015 ). A primary goal of the MASSIVE survey is to measure spatially resolved stellar kinematics for dynamical modeling (e.g., Thomas et al. 2016 ). To achieve a mean signal-to-noise ratio (S/N) of at least 20 pixel −1 , we group individual fibers into spatial bins and co-add the spectra from fibers in a given bin into a single spectrum. The binning scheme is described in detail in Veale et al. ( 2017a ), but we summarize the procedure here briefly for completeness. Central fibers with S/Ns >