An erect image, in optics, is one that appears right-side up.
Some telescopes and other devices, such as the camera obscura present an inverted image on the viewing surface. Various means are used to achieve an erect image. A common example of an erect image is the image of a person in a standard plane mirror.
While the erect image is setting, the inverted image appears to be rising from the surface.
The M49 is an erect image instrument that is magnified by the lenses in the eyepiece.