It's not only the pupils at Farthingbottom School that come from famous families, some of the teachers do too. One of these is the popular chemistry teacher, Dr M. Langley. He's a real sun-worshipper and spends a lot of time topping up his tan. Unfortunately he's not in today because he hasn't achieved his target of 811.44 hours exposure (and obviously turning orange is far more important than teaching his pupils).
Today his less popular brother Dr H. Langley is taking his class. He hates chemistry (and incidentally he hates cryptography even more).
"I don't know why my brother has to spend this many weeks lazing around. Here, take these and complete them" he says as he passes out some sheets of paper, "and tell me what record was held for 52 years."
The pupils look at the pieces of paper and then Felix shouts out "This isn't a periodic table, is it, sir?"
"That's right", answers Dr Langley
"Some of these letter combinations appear more than once", chips in Randolph.
"Of course they do" he replies sharply.
"Are we supposed to be filling in the grey boxes?" asks Marc-Frances.
"No, idiot, the yellow ones", snaps the teacher.
Hesitantly Portia raises her hand and says "Sir, are all these entries up to date and complete?"
"Well, at least there's one bright one in the class", he says. "As of today (1st October, 2015) the entries are correct as I have determined them, but this is not a complete set. I considered there was more than enough information for you without expanding the table any further."
Question: Can you determine which record Dr Langley is referring to?
Edit: After a considerable time during which there had been some muttering, but not a lot of progress, Dr Langley shook his head and said,
"I have heard lots of muttering about stars, but this is not my brother's class. You already know all you need to about his obsession (or would if you could do simple arithmetic). And his obsession should lead the search to find mine. I blame it all on our ancestors. Now hurry up and get finished before I have to throw out the whole chart and start all over again!"