The traditional East Asian calendars divide a year into 24 solar terms . Dàhán or Daikan is the 24th solar term. It begins when the Sun reaches the celestial longitude of 300° and ends when it reaches the longitude of 315°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 300°. In the Gregorian calendar, it usually begins around January 20 and ends around February 4.