gnus-subscribe-newsgroup-hooks

gnus-subscribe-newsgroup-hooks is a variable defined in `gnus-start.el'.
Its value is

nil

• This variable is an alias for `gnus-subscribe-newsgroup-functions'.
• This variable is obsolete since 24.3;
  use `gnus-subscribe-newsgroup-functions' instead.
• This variable may be risky if used as a file-local variable.

Documentation:
*Hooks run after you subscribe to a new group.
The hooks will be called with new group's name as argument.

You can customize this variable.