Breakdown of the 10" Refractor Plate Collection

General

I have cataloged 415 total plates in the collection. The plates fall into three categories. 362 are 6"x7" sized plates and were probably exposed with a camera that attached to the 10" Refractor. They have a plate scale which is consistent with the focal length of the 10" Refractor and we have found a camera/tail piece which is large enough to have held plates of this size. Fifty one (51) of the plates are 4"x7" sized plates and were probably exposed with a wide angle camera that sat piggy-back on the 10" Refractor. We have concluded this because the field of view on the plates are several tens of degrees on a side and several of the 4"x7" plates appear to have been exposed concurrently with 6"x7" plates. The remaining two plates in the collection are odd sizes and appear to be reproductions that were not exposed with the 10" telescope.

Epochs in the Collection

The earliest plate in the collection was exposed on December 18th, 1896. Most of the plates were then exposed between 1897-1900 and 1908-1920 (see figure). The last plate in the collection was exposed on March 2nd, 1946.

10" Refractor Observers

At least twenty five separate individuals labored to expose the plates in the collection. Of these, "Lv" (which 134/415 plates) and "Beal" (97/415) were by far the most prolific observers. We have reason to believe that "Lv" and "F.P.L" are Leavenworth, who was a professor of Astronomy at Minnesota in the early 20th century. We are in the process of attempting to identify the other observers of record. Of greatest interest are the identities of "N" (who was one of the few identifiable original observers) and "Irene Ney" and "Marry Harroum" who are the only observers who are obviously identifiable as female. It is unknown if Irene Ney is related to the mid-20th century UMn Astronomy professor Ed Ney.

Astronomical Research Programs Conducted

There are sixty two (62) identifiable astronomical objects on 406 plates in the collection. We feel that it may be possible to make some guesses about the research programs conducted with the 10" Refractor by analyzing the pattern of objects observed.

The most observed object by far was M42 (the Orion Nebula) which was imaged on at least 148 of 406 plates ranging in epoch from January 5th, 1897 to March 2nd, 1922. We believe this may have been a program for monitoring the nebula supervised by Dr Francis Preserved Leavenworth since he published several articles on the subject in the Astronomical Journal. Leavenworth once reported finding a new star in the Orion Nebula and then retracted the claim shortly thereafter. (Unfortunately the controversial plates are no longer in our collection.) We also know from his published work that Dr Leavenworth conducted a great deal of non-photographic work with the 10" Refractor using a micrometer to measure double stars.

The 23 plates of M57 (the Ring Nebula) from April 28th, 1897 to October 24th, 1913 were probably part of a program supervised by Dr Burt Leroy Newkirk. We believe he may have been attempting to measure the geometric parrallax of M57.

There are also a series of 35 plates taken of Nova Geminorum (DN Gem; HD 50480) between August 4th, 1912 and April 24, 1919 which we believe were meant to measure the decline in brightness for this object from its outburst in 1912. However, we can find no record that this data was ever published except for a note in Astronomische Nachrichten about its position.

The ten (10) plates of asteroids, sixteen (16) plates of comets, and forty four (44) plates of nearby/high proper motion stars, were probably taken for astrometric purposes. Many of these plates have been marked on the non-emulsion side of the plate to note the location of reference stars as one might do prior to measuring the relative positions on a plate. And Dr Leavenworth, William Otis Beal, and Alfred Davis all published papers in the Astronomical Journal reporting the positions and orbits of comets and asteroids using photgraphs made with the 10" Refractor.

Plate Catalog

A full listing of the cataloged plates can be found at:

http://etacar.umn.edu/~martin/teninch/catalog.html