If you have questions about our products you own, Fill out the form below and we will answer any questions you have. Tips: Fields marked with*are required. Digital Zenith Photography Position System ER-DZP-1 (≤0.3″)◆Astronomical latitude measurement error ≤0.3″◆Error in the determination of astronomical longitude ≤0.02S◆Consist of three parts: Digital Zenith photography, location subsystem