Top: folded optical light curves of PSR J1544+4937. The I, R, g, and B data shown as solid circles were obtained with Keck LRIS; the one r′-band point shown as a red square was obtained with CFHT MegaCam. A best-fit model from Icarus with χ2/dof = 1.78 (dof = 42) is shown as solid lines, with model parameters listed. Middle: simultaneous measured LRIS g − I color and B − R color vs. orbital phase, respectively. The weighted mean of g − I = 1.91 and B − R = 1.65 are shown as dashed lines. The colors are consistent with no evolution. Bottom: the ratio of the square root of the projected area over distance in units of R☉ kpc−1 as a function of orbital phase, assuming all the optical emission is from regions with T = 4300 K. The BTSettl atmosphere model is used in the conversion (Allard et al. 2011). The symbols are the same as in the top panel. The solid line shows the best-fit hot dayside model (an isothermal dayside with T = 4300 K and negligible emission from the night side) with inclination angle i = 51° and χ2/dof = 2.24 (dof = 48). The dashed line shows a best-fit hot spot model (an isothermal hot spot with T = 4300 K facing the neutron star, and negligible emission from other regions), with a radius of 57°, centered at latitude 38°, and viewed at i = 52°. The corresponding reduced chi-squared is χ2/dof = 1.51 (dof = 46).