Hello Mike,I presume that you have looked at the information about this comet (discovery circumstances and subsequent development) in Gary Kronk’s Vol 1 pages 369-373 Cometography. This is the “bible” when it comes to researching past comets. If you have not got these pages let me know.It was an extrordinary comet with a description (from Cometography) from an observer in Sussex on 1680 Dec 20 afterthe comet had emerged form the sun’s glare in the southwest that the tail extended to the zenith and was broader than a rainbow. On the same day John Flamsteed said the comet appeared as a beam of light about the width of the moon extending stright up from the horizon. It had become visible before daylight had ended.
Denis Buczynski Secretary Comet Section