Comparison of HAT-P-55b’s transmission spectra. Upper panel: transmission spectra of HAT-P-55b. The blue triangles and black circles show the OSIRIS transmission spectra obtained with the conventional (“band”) and new (“pixel-binned”) methods. The gray dots show the pixel transmission spectrum. The orange squares show the broadband transmission spectrum obtained with MuSCAT2 by Kang et al. (2024). Bottom panel: difference between the new and conventional methods (red diamonds) and the corresponding histogram. The dashed line marks an overall offset of ΔR_p/R_★ = −0.00094.