|     | Harvard-Smithsonian Center for Astrophysics Harvard Observatory Plate Stacks BM Series Characteristics |   | 
| Basics | 
 | |||||||||
| Observatory | 
 | |||||||||
| Filed | 
 | |||||||||
| Record Books: | (2) 1-3222 Online: [01] [02] | |||||||||
| Comments: | Instrument moved to Mexico, February 7, 1941. Plates 1-410 were taken with the 3-in Ross-Lundin lens previously used for the MB series (which see). Plates 411 ff. were taken with a 3-in Ross-Fecker lens. Two new Ross-Fecker lenses were tested, with numbers in this series in February 1937. The first plates were taken with the BM on the old 8-in I mount in Cambridge until this was reclaimed by the I in October 1934. | |||||||||