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>  Docs Center  >  ENVI API  >  ENVI Classic Data Control  >  ENVI_COMPUTE_SUN_ANGLES

### ENVI_COMPUTE_SUN_ANGLES

ENVI_COMPUTE_SUN_ANGLES

Use this function to compute solar elevation and solar azimuth angles for a given time, latitude, and longitude. This function returns a two-element array of double-precision values representing solar elevation and azimuth, respectively, for the selected input values.

## Syntax

Result = ENVI_COMPUTE_SUN_ANGLES (Day, Month, Year, GMTtime, Lat, Lon)

## Arguments

### Day

Use this keyword to specify the day of year for the desired solar angles. Day is an integer value, 1 through 31.

### Month

Use this keyword to specify the month for the desired solar angles. Month is an integer value, 1 through 12.

### Year

Use this keyword to specify the year for the desired solar angles. Year is an integer value of the form yyyy.

### GMTtime

Use this keyword to specify the Greenwich Mean Time (GMT) for the desired solar angles. GMTtime is a floating-point value, 0 through 2400. For example, a value of 1430.0 represents a GMT time of 14:30.

### Lat

Use this keyword to specify the latitude for the desired solar angles. Lat is a floating-point number in degrees. North is positive and South is negative.

### Lon

Use this keyword to specify the longitude for the desired solar angles. Lon is a floating-point number in degrees. East is positive and West is negative.

## Example

The following code computes solar elevation and azimuth angles for 34 degrees north, 117 degrees west on July 4, 1984, 22:45 GMT.

angles = envi_compute_sun_angles(4, 7, 1984, 2245., \$
34., -117.)
print, 'Sun elevation= ', angles[0]
print, 'Sun azimuth= ', angles[1]

## API Version

3.2

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