On the lack of observational records by European astronomers of the 1054 guest star This question relates to the Crab nebula, the Crab Pulsar and the known concurrent supernovae event as recorded by Chinese astronomers in 1054.

I'm wondering, I'm looking at the history of the discovery of the Crab pulsar...and I'm wondering what the reason is (or suspected to be) as to why European records show a discernible lack of observations?
Of the three known medieval supernovae (in 1006, 1054, and 1181 AD), only SN 1006 was definitely recorded by Europeans, and even then, was only discussed in any detail in a single European source (the annals of the monastery of St. Gall in Switzerland). Although there are multiple accounts (some quite detailed) of the supernova of 1006 in Arabic/Islamic records, there is only one known Arabic record of SN 1054, and none for SN 1181. 

Since SN 1006 was by far the brightest of the three, the simplest explanation would be that SN 1054 was, like SN 1181, just not bright enough or long-lasting enough to merit sufficent widespread commentary in Europe. (Remember that China in the 11th Century was a much more advanced society than Europe of the same time, with a dedicated tradition of government-supported astronomical/astrological observations.)