Surface brightness fluctuations ( SBF ) have been detected for three elliptical galaxies—NGC 3379 in the Leo group , NGC 4406 in the Virgo cluster , and NGC 4373 in the Hydra–Centaurus supercluster—using marginally–sampled , deep images taken with the Planetary Camera of the WFPC–2 instrument on the Hubble Space Telescope ( HST ) .
The power spectrum of the fluctuations image is well–fit by an empirical model of the point–spread function ( PSF ) constructed using point sources identified in the field .
The previous ground–based SBF measurements for NGC 3379 and NGC 4406 are recovered , thereby demonstrating the capability of the Planetary Camera of WFPC–2 to measure distances using the SBF technique despite the marginal sampling of the images .
The residual variance due to unresolved sources in all three galaxies is only 2–5 % of the detected fluctuations signal , which confirms the advantage of HST imaging in minimizing the uncertainty of this SBF correction .
Extensive consistency checks , including an independent SBF analysis using an alternate software package , suggest that our internal uncertainties are < 0.02 mag .
The fluctuations magnitude for NGC 4373 is \overline { I } _ { F 814 W } = 31.31 \pm 0.05 mag , corresponding to a distance modulus of ( m - M ) _ { 0 } = 32.99 \pm 0.11 .
This implies a peculiar velocity for this galaxy of 415 \pm 330 km s ^ { -1 } , which is smaller than derived from the D _ { n } – \sigma relation .
These results demonstrate the power of the post–repair HST to measure distances to elliptical galaxies at significant redshifts using the SBF technique .