Ashlesha is nakshatra number 9 of the 27 lunar mansions in Vedic astrology, spanning 106.67° of the zodiac in 13°20' steps. Its planetary lord is Mercury and its presiding deity is Sarpa.
The Moon's position in Ashlesha at birth shapes the Vimshottari Mahadasha sequence — a Ashlesha birth begins life in the Mercury mahadasha, with the balance of that period decided by how far the Moon had travelled through the nakshatra.
Use the free Kundli generator to find whether Ashlesha is your janma nakshatra, and the Panchang to see exactly when the Moon transits Ashlesha on any date.