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Despite the 30-year history of ultra-luminous X-ray sources (ULXs) studies,issues like the majority of their physical natures (i.e., neutron stars,stellar-mass black holes, or intermediate black holes) as well as the accretionmechanisms are still under debate. Expanding the ULX sample size in theliterature is clearly a way to help. To this end, we investigated the X-raysource population, ULXs in particular, in the barred spiral galaxy NGC 1559using a Chandra observation made in 2016. In this 45-ks exposure, 33 X-raypoint sources were detected within the 2.'7 isophotal radius of the galaxy.Among them, 8 ULXs were identified with the criterion of the X-ray luminosity$L_x>10^{39}$ erg s$^{-1}$ (0.3-7~keV). Both X-ray light curves and spectra ofall the sources were examined. Except for some low-count spectra that onlyprovide ambiguous spectral fitting results, all the X-ray sources werebasically spectrally hard and therefore likely have non-thermal origins. Whileno strong X-ray variability was present in most of the sources owing to therelatively short exposure of the observation, we found an intriguing ULX, namedX-24, exhibiting a periodicity of $\sim$7500s with a detection significance of2.7$\sigma$. We speculate that it is the orbital period of the system.Roche-lobe over flow and Roche limit are consistent with the speculation. Thus,we suggest that X-24 may be the one of the rare compact binary ULXs, and hence,a good candidate as a stellar-mass black hole.

Chandra Observation of NGC 1559: Eight Ultraluminous X-ray Sources Including a Compact Binary Candidate