day vs night using elevation angle

[rodrigo-j-goncalves]

I needed to know if it was daytime or nighttime in my study sites (using only lat-lon and date-time), and I found out about pyephem 'angle' :)

This is my function. Any comments to improve are welcome :)
Thanks for this package!

---

import ephem # For daytime calculation

def is_daytime(latitude, longitude, date_time_utc):
    """
    Determines if it is daytime or nighttime at a given location and time.

    Args:
        latitude (float): The latitude of the location (e.g., 40.7128 for New York).
        longitude (float): The longitude of the location (e.g., -74.0060 for New York).
        date_time_utc (str): The date and time in UTC format (e.g., '2025/09/04 12:00:00').

    Returns:
        int: 1 if it's daytime, 
             0 if it's nighttime.
    """
    # Create an observer object
    observer = ephem.Observer()
    observer.lat = str(latitude)
    observer.lon = str(longitude)
    observer.date = date_time_utc

    # Create a Sun object
    sun = ephem.Sun()

    # Calculate the position of the Sun for the given observer and time
    sun.compute(observer)

    # Check the Sun's altitude (angle above the horizon)
    # A positive altitude means the sun is above the horizon (daytime)
    if sun.alt > 0:
        # print(f"the altitude is: {sun.alt}\nDaytime")
        return 1  # It is daytime
    else:
        # print(f"the altitude is: {sun.alt}\nNighttime")
        return 0  # It is nighttime

# ------------------------------------------------------------------

# Test usage
# For the region of Azores region, Portugal
# https://dayspedia.com/time/pt/Azores-/

Lat = 38.66
Lon = -28.07
date_time_test = '2025/09/04 11:13:00'

print(f'Did you say is daytime at the Azores [{Lat}, {Lon}], on {date_time_test} ?')
print(f'Well.... that would be {(is_daytime(Lat, Lon, date_time_test) == 1)}!!')