The ornamental design for a ceilingpanel, as shown and described.
FIG. 1 is a front perspective view of a ceiling panel according to our new design, as seen when mounted on a ceiling, illustrating unclaimed shading on a surface of each of four panel components;
FIG. 2 is a front plan view of the design of FIG. 1, illustrating shading relative to an unclaimed ridge line extending between the outside corner and the inside corner of each of the four panel components;
FIG. 3 is a side end view of FIG. 1, each of the four side-end views being the same; and,
FIG. 4 is a rear view of FIG. 1, showing an unclaimed ceiling-facing surface.
The dash-dash broken lines illustrate environmental structure and form no part of the claimed design.