Dhanurmas is the 30-day period of Sun’s transition from Dhanu Rasi (Sagittarius) to Makar Rasi (Capricorn). Dhanurmas 2017 – 2018 is from December 16, 2017 to January 13, 2018. Dhanurmas is not an independent month in most of the Indian calendars calendars except for the Malayalam calendar followed in Kerala. In Malayalam calendar the month from mid December to mid January is known as Dhanu Masam.
Dhanurmas begins in the middle of Margashirsh month in Telugu, Kannada, Gujarati and Marathi calendar. In North Indian calendars it begins during the Krishna Paksha of Poush month. Dhanur Mas is basically the period the sun shifts from the Dhanur rashi to Makar rashi and it ends on the Makar Sankranti.
Dhanurmas is also known as Marghazhi month in Tamil Nadu and is a highly auspicious period for Vishnu devotees.
The Ekadasi falling during the Dhanurmas period is considered highly auspicious. In
South India, especially the Vaikunta Ekadasi which falls during the waning phase of the moon in Dhanurmas attracts thousands of devotees to important Vishnu devotees for the passing through Moksha Dwaram or Swarga Vathil.