[AZ-Observing] History in My Hands

The featured program at last night's monthly meeting of the Coconino  
Astronomical Society was a behind the scenes tour of Lowell Observatory led by  
Kevin 
Schindler. Schindler is the educational program supervisor at Lowell. In  
addition to developing programs for school groups, Kevin has an intimate  
knowledge of the observatory's history. He performs as Percival Lowell in a  
one-man 
show about the observatory's founder and has written a history of the  24-inch 
Clark refractor. Kevin's tour took us to facilities not included in the  
program for the general public and concluded with a visit to the archival vault 
 
in the basement of the Slipher building.
 
It is in the Slipher building vault where the photographic plates made with  
the 13-inch Lawrence Lowell astrograph are stored. These include the original  
discovery plates for Pluto. As a former member of the public program staff at 
 Lowell, I'd given and heard this portion of Kevin's presentation several 
times.  So, while the others in our group were focused on Schindler's 
re-telling 
of the  events that took place around Tombaugh's discovery of our Solar 
System's most  distant planet, my focus wandered to a shelf of notebooks near 
where 
I was  standing.
 
The notebooks were labeled "Spectrograph Logs." The fist notebook had a  
white paper tab sticking out from a page near the back. I carefully pulled the  
small hardbound booklet from the shelf and read the tab, "And. Neb."  
Immediately, I sensed that this might be a record of the one of the most  
significant 
scientific discoveries of the 20th century. Flipping to the tabbed  page 
confirmed that suspicion.
 
Vesto M. Slipher, the namesake of the building in which we were standing,  
was the first person to make spectrographic observations of galaxies beyond the 
 
Milky Way. He did his work with a Brashear spectrograph attached to the back 
end  of the 24-inch Clark refractor. Arguably, the most significant 
observation he  made in this field was that of December 30, 1912, to January 1, 
1913.
 
Over the course of two nights, Slipher made an exposure recording the  
spectrum of M31, better known as the Andromeda Nebula in those days. Analysis 
of  
this spectrum revealed that M31 was moving through space at a rate surpassing  
that of any other known object. Throughout the remainder of the second decade 
of  the 20th century, Slipher made spectral observations showing that all the 
spiral  nebulae had motions as fast or faster than the Andromeda Nebula. This 
turned out  to be the first solid evidence that these objects resided far 
beyond the Milky  Way. And more than a decade later, Edwin Hubble would cite 
Slipher's work as  being crucial in his development of the theory of an 
expanding 
universe.
 
Reading the handwritten notes in that booklet, I could see that Slipher had  
exposed a chemically treated glass slide for a little longer than 4 hours the  
first night, and had continued the exposure for nearly 7 hours the following  
night. In total, he had manually guided the 24-inch Clark through an 11-hour  
exposure to record this galaxy's spectral bar code. I wondered if he had 
entered  these notes at the end of two very long and tiring nights' work; if he 
had felt  a sense of discovery when first seeing the spectrum; and how long it 
had taken  before he came to the conclusion that such incredible rates of 
motion could only  be explained if the objects were far beyond our home galaxy?
 
What a remarkable experience that was for me, to finish a very special tour  
of Lowell Observatory with a real piece of history in my hands.
 
Regards,
 
Bill in Flagstaff

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