What are you trying to do? Give it light or heat the cage?
Heat, I would go with a ceramic heat emitter or a radiant heat panel and then you could use a thermostat, I preferred che's over a heat lamps and rhp rock. Other than that I have no idea what a gtp requires! I eventually want one though
I use a radiant heat panel on a thermostat for my GTP with great success. Then there's also a fluorescent in his cage for light.
You can put heat lamps on a thermostat but other than the annoyance of a light flickering on and off all day long I've also read it will KILL the life of your bulb.