tokens: rays, and calibrate the absolute flux to reduce the raw SAMI observations (Allen et al. 2015 ). Each galaxy field was observed in a set of approximately seven 30 minute exposures that are aligned together by fitting the galaxy position within each hexabundle with a two-dimensional Gaussian and fitting a simple empirical model describing the telescope offset and atmospheric refraction to the centroids. The exposures are then combined to produce a spectral cube with regular 05 spaxels, with a median seeing of 21. More details for Data Release 1 and Data Release 2 reduction can be found in Green et al. ( 2018 ) and Scott et al. ( 2018 ), respectively. 2.2. Sample Selection The GAMA group sample includes all galaxy associations with two or more members, so to ensure the robustness of our group sample, we first select all SAMI observed galaxies that belong to GAMA halos with at least five members to ensure that they have a robustly estimated velocity dispersion (Robotham et al. 2011 ). Moreover, only galaxies classified as cluster members by Owers et al. ( 2017 ) are taken as cluster galaxies. This gives us an initial sample of 574 galaxies (out of a potential 2502 observed by GAMA) in 205 groups in the GAMA regions and 861 galaxies in eight clusters. Stellar population measurements are compromised for 100 galaxies because nearby galaxies or stars affect their observation (van de Sande et al. 2017 ). In addition, we also exclude three more galaxies whose g − i colors suggest contamination from other objects in the field of view and eight galaxies whose annuli do not reflect the shape of their isophotes and/or the central bin is not well aligned with the peak of their flux map (since they could lead to a biased gradient). In this paper, we are particularly interested in whether the evolution of central and satellite galaxies has an environmental dependence. We focus on the passive central galaxies to ensure a like-to-like comparison in determining how their central and satellite status affects their stellar population gradients. We use the SAMI spectroscopic classifications presented in Owers et al. ( 2019 ) to select a homogeneous sample. The galaxies are classified as star-forming, passive, or H δ -strong using the absorption and emission line properties of each SAMI spectrum. We select 843 passive galaxies; of these, 98 are central and 745 are satellite galaxies (Figure 1 ). Figure 1. Distribution of g − i color with stellar mass as a function of galaxy classification for the galaxies included in SAMI v0.11. Unselected passive galaxies are shown as green crosses. Galaxies selected in the final sample are shown as red crosses, and nonpassive galaxies are shown as black crosses. The dotted line is the stellar mass cut at ; galaxies below this mass are excluded from the final sample. To ensure the stellar population measurements we use are reliable, we exclude all galaxies with masses less than , owing to the low signal-to-noise ratio (S/N) and
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