Example image of eyePlorer eyePlorer map for 'Mural instrument': Meridian (geography) Degree (angle) Arc (geometry) Astronomical object Alidade Telescope Elevation Sextant (astronomical) Sidereal time Astronomical transit Declination Right ascension 994 Abu-Mahmud al-Khujandi Rey, Iran Ulugh Beg Tycho Brahe Uraniborg Ven, Sweden Royal Observatory, Greenwich Alexandria Ptolemy Quadrans Muralis John Bird (astronomer) Transit instrument Quadrant (instrument) List of inventors Timeline of historic inventions Mannheim Observatory Timeline of science and engineering in the Islamic world Muhammad ibn Mūsā al-Khwārizmī Astronomy in medieval Islam