The fraction of residual particles N in 85Rb bosenovae is observed to satisfy N/2⩽N<N, where N/2 appears to be a strict lower bound. Here, we point out that Bose-Einstein condensates of particles of integer spin possess an ambiguity to a constituency of pairs. We explain the lower bound N/2 by the formation of pairs produced in collapse. Pair formation reduced the critical temperature by a factor of about three, sufficient for an instability to produce a prompt explosion. We propose a recount following forced pair dissociation upon exposure to an X-ray flash.