The Harvard College Observatory plates come from a network of observatories which provided full coverage of both celestial hemispheres. Below lists the known telescope locations. There are currently 28 observatories in the database.

• Harvard College Observatory, Cambridge, MA
• Oak Ridge, Harvard, MA
• Boyden Station, Arequipa, Peru
• Boyden Observatory, Bloemfontein, South Africa
• Cerro Tololo Inter-American Observatory (CTIO), Chile
• Mount John​, New Zealand
• Willows, CA
• Mount Harvard, Peru
• Taunton, MA
• Chuquicamata, Chile
• San Jose, Peru
• Nantucket, MA
• Mount Hopkins, AZ
• Norwell, MA
• Hanover, South Africa
• Mandeville, Jamaica
• El Leoncito, Argentina
• Wilsons Peak, CO
• Ossipee, NH
• Austin, TX
• McDonald Observatory, Fort Davis, TX
• Asiago Observatory, Asiago, Italy
• Palomar Observatory, CA
• Lowell Observatory, Flagstaff, AZ
• Doña Ana, NM
• Organ Pass, NM
• Soledad, NM
• Sacramento Peak, NM