What kinds of coordinate can keep the Hawking temperature invariant for   the static spherically symmetric black hole?
  By studying the Hawking radiation of the most general static spherically symmetric black hole arising from scalar and Dirac particles tunnelling, we find the Hawking temperature is invariant in the general coordinate representation (\ref{arbitrary1}), which satisfies two conditions: a) its radial coordinate transformation is regular at the event horizon; and b) there is a time-like Killing vector. 
Chikun Ding and Jiliang Jing