When are rated challenges conducted?


I am interested to increase my ratings.
I have checked some posts and understood we need to participate in the rated challenges.
I started looking for them, however, I could not find any. I have checked the calendar as well.
Could anyone please help to understand when are they conducted and how can we participate in the same?

Mainly there are three rated challenges that happen on Codechef every month.
Long Challange-Currently Ongoing
Cook-Off-Cancelled this month
Lunchtime-Date not announced but will take place after CookOff

Apart from these contests, there are some external rated contests as well.

Refer to this for more information [Monthly Programming Competition | Codechef]