solposx.solarposition.usno

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solposx.solarposition.usno#

solposx.solarposition.usno(times, latitude, longitude, *, delta_t=67.0, gmst_option=1)#

Calculate solar position using the USNO algorithm.

The U.S. Naval Observatory (USNO) algorithm is provided in [1].

Parameters:

  • times (pandas.DatetimeIndex) – Timestamps - must be localized. Prior to 1970 and far in the future UTC and UT1 may deviate significantly. For such use cases, UT1 times should be provided.

  • latitude (float) – Latitude in decimal degrees. Positive north of equator, negative to south. [degrees]

  • longitude (float) – Longitude in decimal degrees. Positive east of prime meridian, negative to west. [degrees]

  • delta_t (numeric, default : 67.0) – Difference between terrestrial time and UT1. If delta_t is None, uses pvlib.spa.calculate_deltat() using times.year and times.month from pandas.DatetimeIndex. For most simulations the default delta_t is sufficient. The USNO has historical and forecasted delta_t [2]. [seconds]

  • gmst_option (int, default : 1) – Different ways of calculating the Greenwich mean sidereal time. gmst_option needs to be either 1 or 2. See [1].

Returns:

DataFrame with the following columns (all values in degrees):

  • elevation : actual sun elevation (not accounting for refraction).

  • zenith : actual sun zenith (not accounting for refraction).

  • azimuth : sun azimuth, east of north.

Return type:

pandas.DataFrame

References

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