Government UAS pilot reported conducting a mission in controlled airspace without airspace authorization.

Narrative

On the morning of Day 0; I; an Officer with a Police Department SWAT team; conducted a sUAS mission for pre-operational footage of a targeted location for a warrant service in the coming days. This specific morning while conducting a flight in controlled airspace (Class B) it was raining and pretty windy. I observed the air space to be a 200 ft. ceiling where I was launching from; Location X; but failed to recognize that the location where I needed to fly and conduct a pre-operational flight was in 0ft airspace. The target location was on the very edge of the 200 ft. and 0 ft. airspace. The flight took approximately 7 minutes starting from XA19 hrs. and landing at XA26 hrs.I did not recognize the error until after the flight. I entered into the 0 ft. airspace at approximately XA20 hrs. and 266 ft. I realized I was too high and descended below 200 ft. thinking I was in the 200 ft. ceiling airspace still. I exited the 0 ft. ceiling airspace at approximately XA25 hrs.After recognizing the error; I have taken steps to correct this error for any future operations.