A luminaire comprising: a housing delimiting a light exit window and comprising a reflective inner surface facing the light exit window; an elongate light guide mounted in the housing and partially covering the light exit window by extending in an elongation direction across a central region of the light exit window, the elongate light guide comprising: a first major surface facing the reflective inner surface; a second major surface opposite the first major surface; and a pair of opposing side surfaces being arranged at opposite ends of the elongate light guide in said elongation direction, and extending between the first major surface and the second major surface; and at least one light source arranged to couple light into the light guide; wherein the elongate light guide leaves exposed a pair of further regions of the light exit window adjacent to the central region, and characterized in that the light guide further comprises a plurality of light outcoupling structures proximal to the second major surface arranged to redirect light onto the reflective inner surface through the first major surface, in that the at least one light source is arranged to couple light into the light guide via one of said opposing side surface, and in that the light exit window has a circular outline. a housing delimiting a light exit window and comprising a reflective inner surface facing the light exit window; an elongate light guide mounted in the housing and partially covering the light exit window by extending in an elongation direction across a central region of the light exit window, the elongate light guide comprising: a first major surface facing the reflective inner surface; a second major surface opposite the first major surface; and a pair of opposing side surfaces being arranged at opposite ends of the elongate light guide in said elongation direction, and extending between the first major surface and the second major surface; and at least one light source arranged to couple light into the light guide; wherein the elongate light guide leaves exposed a pair of further regions of the light exit window adjacent to the central region, and characterized in that the light guide further comprises a plurality of light outcoupling structures proximal to the second major surface arranged to redirect light onto the reflective inner surface through the first major surface, in that the at least one light source is arranged to couple light into the light guide via one of said opposing side surface, and in that the light exit window has a circular outline. a first major surface facing the reflective inner surface; a second major surface opposite the first major surface; and a pair of opposing side surfaces being arranged at opposite ends of the elongate light guide in said elongation direction, and extending between the first major surface and the second major surface; and at least one light source arranged to couple light into the light guide; wherein the elongate light guide leaves exposed a pair of further regions of the light exit window adjacent to the central region, and characterized in that the light guide further comprises a plurality of light outcoupling structures proximal to the second major surface arranged to redirect light onto the reflective inner surface through the first major surface, in that the at least one light source is arranged to couple light into the light guide via one of said opposing side surface, and in that the light exit window has a circular outline.