Diameters Star Sp Type (mas) 1 Diameter ( )2 NR Vul K3 I (L05) 3.04 0.1 4.12 BD+354077 M2.5 I (L05) 3.18 0.13 5.45 BI Cyg M3-M4 I (L05) 5.16 0.34 9.21 RW Cyg M3 I (L05) 5.09 0.36 11.8 AZ Cyg M3 Iab (M19) 3.74 0.18 8.41 V424 Lac M0 I (L05) 3.77 0.08 12.6 V 336 And M2Ib (KM89) 2.46 0.05 3.08 AD Per M2.5 Iab (M19) 2.39 0.15 8.39 BU Per M3 I (L05) 2.27 0.29 21.0 FZ Per M1.5 (M19) 1.8 0.24 13.7 KK Per M2 Iab-Ib (M19) 2.27 0.10 2.17 SU Per M3-M4 I (L 05) 3.20 0.21 10.9 RS Per M4 I (L 05) 2.96 0.13 5.13 S Per M4.5 I (L 05) 4.08 0.36 6.91 W Per M4.5 I (L05) 2.93 0.12 6.14 XX Per M4 Ib (M19) 2.77 0.16 5.90 6 Gem M1-M2 Ia-Iab (KM89) 4.11 0.48 49.3 TV Gem M1 I (L 05) 3.41 0.53 37.5 WY Gem M2 Iabep+ (M19) 2.68 0.03 3.96 An Interferometric Imaging Survey of Red Supergiant Stars Ryan P. Norris (New Mexico Tech) Abstract Red supergiant stars (RSGs) are an end stage of massive star evolution. Among the notable behaviors of stars during this stage are their irregular and semi- regular variability and mass-loss. In order to better understand the sources of these phenomena, we collected high resolution optical interferometric observations of 17 RSGs using the Center for High Angular Resolution Astronomy (CHARA) Array at Mount Wilson between 2015 and 2016. Here, we present stellar diameters derived from these data. We comment on evidence of surface asymmetries on those stars for which we were able to obtain closure phases and present an example image for one of these objects. In addition, we have obtained near-contemporaneous spectroscopy of these stars using SpeX on the NASA InfraRed Telescope Facility (IRTF). We have developed libraries of synthetic spectra derived from spherical MARCS, PHOENIX, and SATLAS stellar atmospheres, and are currently working to derive fundamental stellar parameters with these data. Diameter Fitting We used the OITOOLS.jl1 package to run a grid search for fitting model limb-darkened disks to the squared visibilities. Future efforts will resistrict the fit to the first two lobes of the visibility curve in order to avoid effects from large surface features. 1:https://github.com/fabienbaron/OITOOLS.jl Figure 1: Example χ2 surface for the linearally limb-darkened disk of RS Per. 1: Linear limb-darkening coefficent. 2: Using Gaia parallaxes as reported in Bailer-Jones et al. 2018 References 1)Bailer-Jones, C. A. L., Rybizki, J., Fouesneau, M.,Mantelet, G., & Andrae, R. 2018, AJ, 156, 58 2)Keenan P. C., McNeil R. C., 1989,ApJS, 71, 245 (KM89) 3)Levesque, E. M., Massey, P., Olsen, K. A. G., et al. 2005,ApJ,628, 973 (L05) 4) Norris et al. 2021. Submitted.. 5)Messineo, M., & Brown, A. G. A. 2019,AJ,158, 20 (M19) Example Imaging Image Reconstruction Of the 17 stars observed 10 have enough (u, v) coverage for image reconstruction and have closure phases suggesting surface assymetries. In Figure 2, we present an example image for RS Per. Details of the reconstruction process can be found in Norris et al. 2021. We used SQUEEZE1 and the OITOOLS.jl package to reconstruct images. 1:https://github.com/fabienbaron/squeeze Figure 2: Image reconstruction of RS Per (top) and corresponding uv coverage (bottom). Beam size is depicted in the lower right corner of the image. Image was reconstructed using SQUEEZE and total variation and Laplacian regularizers.