275 and Tacitus became emperor in September, which does not fit the surviving evidence. Contemporary documentation from Egypt suggests that the interval was at the most only 10 or 11 weeks, and perhaps as short as just 5 weeks. If accounting for the time it took for the news of Aurelian's death to reach Italy, and the information to spread out into the empire from there, the interval of the supposed interregnum is very brief. The Epitome of Histories by the 12th-century historian Joannes Zonaras mentions an "interregnum" between Aurelian and Tacitus, but he likely used the 4th-century Enmannsche Kaisergeschichte as a source, wherein the term "interregnum" more probably referred to the time between Aurelian and Probus, regarding the briefly reigning emperors Tacitus and Florianus as sorts of "inter-regents". Other ancient historians, such as Eusebius, are known to sometimes have regarded Tacitus and Florianus as too insignificant to count. Despite the dismissal of a lengthy interregnum as fantasy, and the lack of unequivocal evidence for any extended interregnum at all, many historians still believe that there was a brief interregnum of some sort, often citing spurious numismatic (coin-based) evidence. Some coinage once thought to have been minted in the period between Aurelian and Tacitus, bearing the legend and sometimes the letters (interpreted as indicating the Roman Senate assuming control of the government between the reigns of the two emperors), have recently been re-assigned to the earlier reign of Gallienus. Severina's status Some scholars supporting the notion of an interregnum between Aurelian and Tacitus have turned to speculating based only on numismatic evidence that the Roman Empire was governed, at least nominally, by Severina until Tacitus became emperor. Though many numismatists view Severina's tenure as ruler of the empire as beyond dispute, it is only speculation and there are serious doubts with the interpretation given that it is only based in the interpretation of certain coins and that literary sources are entirely silent on the matter. Based on the increasing quantity of her coinage towards the end of Aurelian's reign, it has been argued that some coins were minted of Severina also after Aurelian's death, though Alaric Watson, author of a biography on Aurelian, dismissed this argument since he found it based more in a desire to find coins supposedly dating to the interregnum rather than the actual features of the coinage. According to the numismatist David L. Vagi, Severina ruling