liquid mirror telescope

A liquid mirror telescope is a reflector telescope whose primary mirror is formed of a rotating open container of a reflective liquid such as mercury, i.e., a liquid mirror. Under gravity, the upper surface forms into an upward-facing concave parabola, useful for a reflector telescope. However, the resulting mirror is in a fixed position, aimed straight up, though very slight aiming can be accomplished by moving the rest of the optics, with some decrease in the quality of the image. The the International Liquid Mirror Telescope (ILMT) is an example liquid mirror telescope and the Large Zenith Telescope (LZT) is a past example.