In this paper we report accurate Chandra positions for two ultraluminous X-ray sources : NGC 7319-X4 at Right Ascension ( RA ) = 339.02917 ( 2 ) ^ { \circ } , Declination ( Dec ) = 33.97476 ( 2 ) ^ { \circ } and NGC 5474-X1 at RA = 211.24859 ( 3 ) ^ { \circ } , Dec = 53.63584 ( 3 ) ^ { \circ } .
We perform bore-sight corrections on the Chandra X-ray Satellite observations of these sources to get to these accurate positions of the X-ray sources and match these positions with archival optical data from the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope .
We do not find the optical counterparts : the limiting absolute magnitudes of the observations in the WFPC2 standard magnitude system are B = -7.9 , V = -8.7 and I = -9.3 for NGC 7319-X4 and U = -6.4 for NGC 5474-X1 .
We report on the X-ray spectral properties and we find evidence for X-ray variability in NGC 5474-X1 .
Finally , we briefly discuss several options for the nature of these ULXs .