Supermassive black hole mass measurements for NGC 1300 and 2748 based on Hubble Space Telescope emission-line gas kinematics

We present Space Telescope Imaging Spectrograph emission-line spectra of the central regions of the spiral galaxies NGC 1300 and 2748. From the derived kinematics of the nuclear gas we have found evidence for central supermassive black holes in both galaxies. The estimated masses of the black holes in NGC 1300 and 2748 are (6.6+6.3−3.2) × 107 and (4.4+3.5−3.6) × 107 M⊙, respectively (both at the 95 per cent confidence level). These two black hole mass estimates contribute to the poorly sampled low-mass end of the nuclear black hole mass spectrum.