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Hi Maik and all, I have been thinking about the Great Comet of -43 and the possibility that it was a return of the 1744 comet.? If you are correct about the orbit of this latter object (and you certainly make a good case in my opinion) and the comet returned around the middle of -43, it seems strange that it would have passed by unrecorded. True, the apparition would not have been a good one, but with the very bright intrinsic magnitude of this object, it is unlikely that it would not have been seen. It is also unlikely that, at the same time, another bright comet appeared (though not ipossible of course). The Chinese observations note that this comet was "reddish-yellow" in colour, presumably due to sodium boiling out from dust particles. This implies that the comet was large, dusty and relatively close to the Sun. It also suggests that it was bright enough for a definite colour to be perceived.? My question is whether the Chinese dates could be incorrect. As you point out, there are some difficulties with the records (the comet could not have been in Orion, for instance) and all the records were composed well after the event itself. Is it possible that the Chinese observations were given the wrong date? It would not be the only time that this happened in ancient Chinese chronicles, at least, as their translations have come down to us. Assuming a perihelion date at the end of July, if the Chinese observations were made during July instead of June, the fit both with the Roman comet and the computed return of 1744 seem to be better, I think. Unfortunately, I do not have a program that can handle such early dates, but as best as I can determine, the comet would indeed have been in the NW sky in the middle of July, with a tail most likely pointing toward the NE as recorded. It would have been deep in twilight, but bright enough to be conspicuous, especially if it displayed a bright dust tail. Indeed, the relatively modest length of the recorded tail (5 - 10 degrees) might even suggest that the observations were made in twilight, with the fainter extremities of the tail being invisible against a bright sky. The Chinese and Roman observations may overlap as the comet drifted further into twilight but became brighter. As seen in Rome, the comet became visible some time during the hour before sunset, at small elngation and setting soon after the Sun. There is no indication that the comet was visible at night. This is just a suggestion and I realize that it could be criticized as altering the data to fit the hypothesis. But I simply suggest it as a possible line of thought. Cheers, David
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