Cinematography : The Golden Hour… App? by Christopher Dyer

Hi all… I have a short documentary shoot coming up next weekend, so this morning I scouted the location we're shooting to plan shots amongst other things. I got there at sunrise to see how the lighting looked, of course, it'll be perfect and amazing. Later, I thought it would be nice to have an App on my iPhone that clearly and simply shows me the time the golden hour will be each day at sunrise and sunset. When I searched, I found there were many, many apps that tell you when the Golden Hour / Blue Hour are each day. Based on screenshots, some of the apps looked overly complicated, some looked simple, some looked cheap while others looked pretty high-end. Many were free and many cost something. I'm curious if anyone has used a particular Golden Hour app on their iPhone and has a recommendation. I don't mind paying for one if it's the best one to have—I just can't seem to determine which one is the best. Suggestions? Which ones do you use? Or, is it just a waste of time/money?