  There are currently many large-field surveys operational and planned
including the powerful Vera C. Rubin Observatory Legacy Survey of Space and
Time. These surveys will increase the number and diversity of transients
dramatically. However, for some transients, like supernovae (SNe), we can gain
more understanding by directed observations (e.g. shock breakout, $\gamma$-ray
detections) than by simply increasing the sample size. For example, the initial
emission from these transients can be a powerful probe of these explosions.
Upcoming ground-based detectors are not ideally suited to observe the initial
emission (shock emergence) of these transients. These observations require a
large field-of-view X-ray mission with a UV follow up within the first hour of
shock breakout. The emission in the first one hour to even one day provides
strong constraints on the stellar radius and asymmetries in the outer layers of
stars, the properties of the circumstellar medium (e.g. inhomogeneities in the
wind for core-collapse SNe, accreting companion in thermonuclear SNe), and the
transition region between these two. This paper describes a simulation for the
number of SNe that could be seen by a large field of view lobster eye X-ray and
UV observatory.
