# How to calculate moon overhead and underfoot time?

For hunting purposes, some hunters follow the moon phases to hunt accordingly. To give some context, here's some links:

I would like to know how to calculate the time when the moon is directly overhead in the sky (moon overhead) and when the moon is directly underfoot in the opposite side of the earth's sky (moon underfoot). Those are the information that I have:

• Moon rise time
• Moon set time
• Moon phase (first, full, last, new)

Those information come from AccuWeather API: https://apidev.accuweather.com/developers/astronomyAPIGuide#MoonPhasesRange. There are some other APIs that give the moon phase in degree format or between 0 and 1 but we chose AccuWeather.

I tried to calculate this with only the moon rise and set time. I thought that simply calculating halfway between rise and set time will suffice. However, I didn't always get the same results as the moon overhead and underfoot in this website: http://www.solunarforecast.com/solunarcalendar.aspx

Is there a formula to get the time of moon overhead and underfoot with the information that I have?

UPDATE

I used the definition

when the moon is directly overhead in the sky

because that is what I found from my research. However, it's seems the correct definition is when the moon is at highest point in the sky.

Also, since it's for hunting purposes, I don't need the time to be accurate to the minute (but that could be nice).

• The term "directly" is problematic. Do you mean within 1 degree, or 1 arc second, or exactly? Of course exactly won't get you any useful results. Just for example see answers to How long does it take for ISS to travel over all possible places of the world one time? and What are the chances that the ISS transits the moon as seen from your house (or headquarters)?
– uhoh
Commented May 11, 2020 at 5:35
• It appears from the link that you gave that you are not talking about the moon being literally overhead, but being at it's highest point. This is called the culmination of the moon. It also depends on how accurate you need the answer to be, and that in turn depends on why you need this. It also depends on what you mean by "simple". Is trigonometry "simple"? Is geoastro.de/TransitCulm/index.html simple? Commented May 11, 2020 at 6:54
• @JamesK I've updated my question to give more context. Also, you're right it's when the moon is the highest point in the sky for moon overhead. Thanks for pointing out ! Commented May 11, 2020 at 12:04