When to tie the rakhi
The rakhi is tied before the sutak begins, or after the eclipse is over and everyone has bathed. If the eclipse is in the evening or at night, its sutak begins nine hours earlier, often in the morning or afternoon, so the rakhi is tied in the morning before that, provided Bhadra has ended. If Bhadra and the sutak together leave no time in the day, many families tie the rakhi after the eclipse ends, after bathing, or on the next morning.
If the eclipse is not visible where you live, its sutak does not apply there, and the usual rules for the day are followed.
Rules around an eclipse
For a lunar eclipse the sutak, the period of inauspiciousness, begins nine hours before the eclipse (for a solar eclipse, twelve hours). During sutak and the eclipse, temples close, images are not touched, cooking and eating are avoided, and tulasi or kusha leaves are put in stored food and water. Children, the elderly, the sick and pregnant women are exempt from the fast. During the eclipse itself people chant mantras, which are said to bear many times their usual merit. When it ends, the house is cleaned, everyone bathes, the temple is purified and charity is given. Sutak applies only where the eclipse is visible.