We have studied the very long‐term temporal properties of the optical emission from Be X‐ray binaries (BeX) in the Small Magellanic Cloud (SMC) over a ∼16 yr baseline, using light curves from the MAssive Compact Halo Objects (MACHO) and Optical Gravitational Lensing Experiment (OGLE) data bases. All the BeX in our sample display superorbital variations, many of them quasi‐periodic on time scales of ∼200–3000 d. These long‐term variations are believed to be related to the formation and depletion of the circumstellar disc around the Be star, and we compare and contrast their behaviour with that of the Large Magellanic Cloud (LMC)’s prototypical BeX, A0538‐66. The great majority of sources show a correlation of outburst amplitude with brightness (the opposite to that seen in A0538‐66) although the amplitudes are mostly small (≤0.1 mag). We suggest this is an orbital inclination effect. In addition, we have also detected many of their optical orbital periodicities, visible as a series of precisely regular outbursts. Furthermore, the amplitude of these periodic outbursts can vary through the long‐term superorbital cycle, and we discuss mechanisms which can produce this effect, as well as examining an apparent correlation between these periodicities. As a by‐product of this variation survey we have compiled a list of all the reported SMC BeX orbital and superorbital periodicities at optical and X‐ray wavelengths.

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We present a multi-wavelength analysis of the very fast X-ray transient MAXI J0158-744, which was detected by MAXI/GSC on 2011 November 11. The subsequent exponential decline of the Xray flux was followed with Swift observations, all of which revealed spectra with low temperatures (∼100eV) indicating that MAXI J0158-744 is a new Supersoft Source (SSS). The Swift X-ray spectra near maximum show features around 0.8 keV that we interpret as possible absorption from O viii, and emission from O, Fe, and Ne lines. We obtained SAAO and ESO optical spectra of the counterpart early in the outburst and several weeks later. The early spectrum is dominated by strong Balmer and He i emission, together with weaker He ii emission. The later spectrum reveals absorption features that indicate a B1/2IIIe spectral type, and all spectral features are at velocities consistent with the Small Magellanic Cloud. At this distance, it is a luminous SSS (> 10 37 erg s −1 ) but whose brief peak luminosity of > 10 39 erg s −1 in the 2-4 keV band makes it the brightest SSS yet seen at "hard" X-rays. We propose that MAXI J0158-744 is a Be-WD binary, and the first example to possibly enter ULX territory. The brief hard X-ray flash could possibly be a result of the interaction of the ejected nova shell with the B star wind in which the white dwarf (WD) is embedded. This makes MAXI J0158-744 only the third Be/WD system in the Magellanic Clouds, but it is by far the most luminous. The properties of MAXI J0158-744 give weight to previous suggestions that SSS in nearby galaxies are associated with early-type stellar systems.