The scales of Hamsadhwani are as follows :
Aarohanam (Ascending) : S R2 G3 P N3 S’
Avarohanam (Descending) : S’ N3 P G3 R2 S
Hamsadhwani is a janya raga, derived from Shankarabharanam (below), 29th on the Melakarta scale.
It is an auspicious raga, very suitable for beginnings and perhaps that is why there are so many compositions on Lord Ganesha in this raga. There are many well known compositions in Hamsadhwani, a few of them are Vatapi Ganaptim by Muthuswami Dikshithar, Raghunayaka by Tyagaraja, Karunanidhiye by Sudhananda Bharathi, and Gam Ganapathe by Muttiah Bhagavathar.
Tamil readers may enjoy the following discussion on the raga by Charulatha Mani.
Note : The 12 notes in the octave are named as below. Please note that C is used as Sa for the sake of simplicity as the scale is relative in Carnatic Music. Also note that the scales paint only a superficial picture of the raga as the gamakas(ornamentations) are a very important part of a raga.