Historical clue formulations

• Memo taker — 2019-09-15
• One paying close attention — 2015-01-19
• Observant individual — 2012-08-03
• Observant one — 2009-09-12
• Observant one — 2007-07-29
• Observant one — 2005-07-17
• Observer — 2005-02-28
• Observant one — 2003-05-12
• Keen-eyed one — 2003-04-25
• Observant one — 2002-10-06
• Observant one — 1999-10-24
• Citer — 1998-11-02
• Observer — 1998-07-07