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tokens: in Column 6. The uncertainties are at the 1σ level and are calculated with behr (Section 3.2 ). (9) Logarithmic 0.5–7 keV peak flux converted from the peak count rate in Fig. 6 with the method in Section 2.2.1 . (10) The Method(s) responsible for identifying the transient candidate. In Fig. 6 (left), we show the light curves of the transient candidates during the observation when the transient happens. The light curves are derived from the X-ray events extracted in Section 3.2 , and are binned by 5-count intervals. The data points in these light curves indicate total count rates, including contributions from the source and background. The estimated average background count rate is marked as the dashed line in each panel of Fig. 6 (left). The durations of XT1 and XT2 tend to be shorter than for other transient candidates (Fig. 6 left). The T 90 values of XT1 and XT2 are and ks, respectively (see Bauer et al. 2017 and Xue et al. 2019 for details). We do not derive T 90 for other sources, because T 90 cannot be derived for many transients that extend beyond the Chandra exposures (e.g. ID3 and ID9 in Fig. 6 left). Also, unlike XT1 and XT2, many of the other transient candidates have non-zero fluxes in the quiescent states, and thus their T 90 calculation requires careful subtraction of the quiescent fluxes, which is beyond the scope of this work. Figure 6. Light curves for each transient candidate. The left-hand panels are light curves for the observation with the transient, with each bin including 5 counts. The horizontal dashed lines indicate the estimated average background count rates. The right-hand panels are long-term light curves with each data point representing a Chandra observation. The transient observation is highlighted in red colour. The horizontal dashed lines indicate a net count rate of zero. We plot the long-term light curves in Fig. 6 (right), where each Chandra observation is represented by a data point. These data points indicate net count rates, which are background-subtracted. As expected, the transient observation generally has a count rate much higher than other observations. However, unlike the CDF-S XT1 and XT2 events, most of the other transient candidates have detectable signals in some of the non-transient observations. Also, CDF-S XT1 and XT2 tend to have higher hardness ratios than the rest of the selected transient candidates (Fig. 5 ). These differences indicate that most of the new transient candidates are physically distinct from CDF-S XT1 and XT2 (see Section 3.3 ). 3.3 Optical/NIR counterparts We have compiled the likelihood counterpart matching results from the survey catalogues (Table 1 ). All the transient candidates have optical/NIR counterparts. The counterpart properties are presented in Table 3 . We also match the counterparts with the Gaia catalogue (Gaia Collaboration 2018 ) using a 1 arcsec matching radius, and mark the sources with non-zero parallax and/or proper motion as ‘star’ in Table