went out there last month
used by V Slipher and his brother E C Slipher
lowell observatory spectrograph
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Re: lowell observatory spectrograph
Very cool!
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Re: lowell observatory spectrograph
Very interesting construction.
regards Rainer
Observatorio Real de 14
San Luis Potosi Mexico
North 22° West 101°
Observatorio Real de 14
San Luis Potosi Mexico
North 22° West 101°
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The Slipher Spectrograph at Lowell Observatory, Flagstaff, Arizona
https://astronomy.com/magazine/news/202 ... -at-lowell
Spectrum of the Sombrero Galaxy (NGC 4594) https://collectionslowellobservatory.om ... /show/1183
Spectrum of the Sombrero Galaxy (NGC 4594) taken by V.M. Slipher. The lines are shifted toward the red end of the spectrum, indicating that the galaxy is receding from Earth. The sharp lines are calibration spectra; the galaxy spectra is the fuzzy stuff.
Slipher’s astronomical studies went in several simultaneous directions. Shortly after his arrival in 1901, the observatory received a state-of-the-art spectrograph made for the 24-inch Clark refractor, the institution’s main instrument. By 1902, Slipher had worked out the bugs with this tricky piece of equipment.
In 1909, Slipher began recording spectra of spiral nebulae, urged on by Lowell, who thought they might show spectral similarities to our solar system. This task was difficult, however, because these objects were faint. Nonetheless, Slipher consulted with astronomers at other observatories and experimented with equipment, including faster lenses and observing techniques that might minimize the difficulty.
In the fall of 1912, Slipher recorded a plate of the “Andromeda Nebula” that he felt was sufficiently good to obtain its radial velocity. No radial velocities of nebulae were known at that time. He recorded better plates in November and December 1912, and still a better result on the nights of December 29, 30, and 31, and into the predawn hours of New Year’s Day 1913. He measured the plates over the first half of January, finding that the nebula was moving three times faster than any previously known object in the universe.
Confusion ensued, and Slipher spent more time measuring the plates. On February 3, 1913, he wrote to Lowell that the Andromeda Nebula was approaching Earth at the unheard-of velocity of 186 miles per second (300 kilometers per second), still an accurate value. “It looks as if you had made a great discovery,” wrote Lowell. “Try some other spiral nebulae for confirmation.”
Slipher next went after what we now call the Sombrero Galaxy (M104) in Virgo. He found its spectral lines shifted far toward the red, indicating that it is receding from Earth at 620 miles per second (1,000 km per second). By the 1914 American Astronomical Society meeting in Evanston, Illinois, Slipher was able to announce results for 15 spirals. Nearly all were receding at high velocities. Three years later, Dutch astronomer Willem de Sitter theorized that the universe is expanding. It was Slipher’s observations of the so-called spiral nebulae that established this fact.
And then in 1923 came Hubble’s discovery of the nature of galaxies. By 1929, Hubble derived his crucial velocity-distance relationship for galaxies, using, as Hubble wrote Slipher, “your velocities and my distances.” Slipher and Hubble had together uncovered the expanding universe, the nature of galaxies, and a way to measure extragalactic distances.
Spectrum of the Sombrero Galaxy (NGC 4594) https://collectionslowellobservatory.om ... /show/1183
Spectrum of the Sombrero Galaxy (NGC 4594) taken by V.M. Slipher. The lines are shifted toward the red end of the spectrum, indicating that the galaxy is receding from Earth. The sharp lines are calibration spectra; the galaxy spectra is the fuzzy stuff.
https://ned.ipac.caltech.edu/level5/Sep ... eman5.htmlSlipher was well aware of the significance of his observations. The velocities of the nebulae are much larger than those of the Galactic stars. He inferred that they lie outside the Milky Way. In his 1917 paper, he wrote:
A letter from Hertzsprung to Slipher in 1914 makes the same point. Hertzsprung wrote:It has for a long time been suggested that the spiral nebulae are stellar systems seen at great distances. This is the so-called “island universe” theory, which regards our stellar system and the Milky Way as a great spiral nebula which we see from within. This theory, it seems to me, gains favor in the present observations.
My … congratulations to your beautiful discovery of the great radial velocity of some spiral nebulae. It seems to me, that with this discovery the great question, if the spirals belong to the system of the milky way or not, is answered with great certainty to the end, that they do not.
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Re: lowell observatory spectrograph
The spectrograph was mounted in the autumn of 1901. Complete, with the necessary counterbalances at the upper end of the telescope, it added 450 pounds to the weight of the telescope tube, which required a corresponding increase in the counterbalances on the declnation axis. The mounting of the refractor is massive, and this considerable increase in the weight upon the bearings has not influenced the running of the driving-clock.
THE LOWELL SPECTROGRAPH
By V. M. Slipher
THE ASTROPHYSICAL JOURNAL
JULY 1904