GnomonicPhoto shows the local True Solar Time in the Smartphone´s camera screen and allows capturing the image of a sun dial at a given time to check the sun dial´s appropriate functioning. Once the image is captured, it is possible to superimpose three labels including gnomonic data of the time of the capture and an additional label with comments before saving. The following information can be addded: - Date and time. - Latitude and longitude. - True Solar Time. - Mean Solar Time. - Sun Azimuth