SIMBAD references

Rapid spectroscopy of GRB afterglows is an important and hard task. Based on the archival XS-GRB spectral database, we here perform a pilot study on the afterglow's spectroscopy in the forthcoming SVOM era in two aspects. First, our simulation indicates that the color acquired from the SVOM/VT blue and red channels is effective in discriminating between low-z (z . 3) and distant GRB candidates until z ∼ 6. Second, by doubling the sample size, we find that the previously proposed global photoionization response of the circumburst gas to the prompt emission (i.e., the CIV/CII-L_iso / E_peak² relationship) is roughly confirmed, although the confirmation is dissatisfactory at the large L_iso / E_peak² end. We believe that this issue can be further addressed in the SVOM era by a larger spectroscopy sample, thanks to its capability of rapid identification of optical candidates of afterglow and its anti-solar pointing strategy.