Background stars observed toward L 1544 in the present study. First panel from the left: DSS color image of L 1544 to delineate the dark patch of the starless core. Second panel: extinction map based on the Herschel/SPIRE far-infrared imaging. Third panel: close-up view of the central part of L 1544, enclosed within the orange rectangle on the second panel. The positions of the 2MASS/WISE sources are marked with crosses. Fourth panel: dust color temperature based on Herschel/SPIRE imaging. The methanol peak observed by Bizzocchi et al. (2014) is shown with orange contours. The half-transparent circle roughly denotes the region where CO is frozen out (Caselli et al. 1999).