How Vespera compensate for the lack of field derotator?

How Vespera compensate for the lack of field derotator?

Vespera realizes unitary exposures of 10s. This is enough so that the field rotation is not visible on the raw images. Thus, the field rotation is compensated when stacking the images. Thanks to our image processing algorithms that take into account the entire signal perceived in the field, it is possible to stack images without limits and field loss.