Updated Flux calculation for instances where background is turned off.
Updated Flux calculation for instances where background is turned off.

DiracInstitute/kbmod,jbkalmbach/kbmod,PWhiddy/kbmod,DiracInstitute/kbmod,DiracInstitute/kbmod,PWhiddy/kbmod,jbkalmbach/kbmod,jbkalmbach/kbmod,DiracInstitute/kbmod,PWhiddy/kbmod,jbkalmbach/kbmod,PWhiddy/kbmod