Chemical element of metals. Cu comes from Cuprum, Fe comes from Ferrum, Ag from Argentum. The symbols were not followed by a period (full stop) as with abbreviations. Later chemical elements were also assigned unique chemical symbols, based on the name of the element, but not necessarily in English. For example, sodium has the chemical symbol 'Na' after the Latin "natrium". The same applies to "W" (wolfram) for tungsten, "Fe" (ferrum) for iron, "Hg" (hydrargyrum) for mercury, "Sn" (stannum) for tin, "K" (kalium) for potassium, "Au" (aurum) for gold, "Ag" (argentum) for silver, "Pb" (plumbum) for lead, "Cu" (cuprum) for copper, and
SN 1054 are not confirmed so conclusively: supernovas of the first millennium (SN 185, SN 386 and SN 393) are established on the basis of a single document each, and so they cannot be confirmed; in relation to the supposed historical supernova which followed the one in 1054, SN 1181, there are legitimate doubts concerning the proposed remnant (3C58) and an object of less than 1000 years of age. Other historical supernovae of which there are written accounts which precede the invention of the telescope (SN 1006, SN 1572 and SN 1604) are however established with certitude. Telescope-era supernovae are of course