A Mystical Night on Mount Wilson
By: Mike Bertin
September 27, 2015 2:16PM PDT
A Mystical Night on Mount Wilson
© Mike Bertin, Irvine, CA Sept 21, 2015
Anyone who knows me knows that I am a Palomar Observatory groupie. I'm a docent there, leading public tours, and giving talks (including one to OCA) about the Observatory's founder, George Ellery Hale. If a person can be in love with a piece of glass and the steel that holds it, I'm in love with Palomar's 200 inch Hale Telescope.
But, having said that, I think the most important telescope in human history is the 100 inch Hooker Telescope on Mount Wilson. With this telescope Edwin Hubble discovered in 1924 that the great "spiral nebulae" in Andromeda (M31) that astronomers had seen in their telescopes for a century was a galaxy outside the Milky Way. And in 1929 he found that other, more distant galaxies (though not M31) were rushing away from ours at incredible speeds -- the universe was expanding. These are two of the most important discoveries in the history of science.
Mount Wilson is one of the observatories founded by George Ellery Hale, and the 100 inch is the third of his four great telescopes. Over the years I've had chances to visit Mount Wilson, but either I was traveling, or I had a conflict, or the visit was rained out. One Saturday night in September I finally made it. I was not disappointed.
OCA member Rich Guy rented an evening on the 100 inch, and generously invited me and a few other OCA members to share the viewing experience. Renting time on the 100 inch is a new program in the last year; only about 150 visitors have had the chance to look through this historic telescope. Ironically, Rich was ill on the night of the viewing, but his daughter, Suzanne, represented the family. Steve Short, Sam Saeed, Barbara Toy, Alan Smallbone, Gary Schones, Kyle Coker, Amir Soheili, and several of their spouses made up the OCA viewing contingent.
It was a warm, clear night, and seeing the starlight stream down through the open dome shutters onto that old telescope was amazing and exciting. Mount Wilson is close to downtown LA, but it's in another world.
Of course I don't believe in ghosts, but the whole evening I was thinking "This is where George Ellery Hale stood on November 2, 1917, at first light for this telescope", and "This is where Edwin Hubble stood in 1924 and 1929 when he first understood the nature of galaxies in the Universe." For me this was a mystical experience.
The evening's program was well organized. Three Mount Wilson staff members, Heven Renteria, Norm Vargas, and Tom Thompson (ex JPL astronomer) were informative, easy going, and excellent guides for our viewing session.
For current visual observing sessions the 100 inch is set up as a "bent Cassegrain" in which the light exits the telescope through the declination axis. From there it is guided through a 6 inch Explore Scientific refractor and diagonal mirror to a spot on the side of the telescope accessible by a ladder. The true field of view of the system was about 5.5 arc minutes, so extended objects like the M11, the Wild Duck Cluster, or large galaxies like Andromeda, don't show their full grandeur -- they are too big for the field of view.
But in the globular clusters we saw individual stars could be resolved all the way to the cluster's center. And I saw more structure in planetary nebulae than I've ever seen visually before. Here's what we looked at between 7:45PM to 1AM, with some editorial comments:
1. The moon -- nice, with many small craters that I would not be able to see in my 10" SCT telescope.
2. M92, a globular cluster in Hercules, smaller than M13 and with stars more densely packed.
3. M57, the Ring Nebula in Lyra.
4. Epsilon Lyra, the Double-Double. There was ample black space between the close members of the Double-Double. With separations of 2.3 and 2.5 arc minutes they were an easy split in the 100 inch.
5. Albireo, the famous color contrast double in Cygnus. Nice, but not spectacular compared to the views in my 10" scope. We could see the color best with the scope slightly de-focused.
6. The Blinking Planetary Nebula, NGC 6826, in Cygnus.
7. Campbell's Hydrogen Star (PK 64+ 5.1), a small planetary nebula in Cygnus, with the hot Wolf Rayet star HD 184738, magnitude 11.3 in the center of a ring of glowing red gas. If you know where to look and your telescope points accurately, you might be able to pick out the center star. But it took the aperture of the Hooker Telescope to let us see the color in the surrounding gas ring.
8. M11, the Wild Duck open cluster in Scutum, ablaze with the light of more than 500 suns. We looked at the center of M11. We couldn't see the characteristic V shape of the Wild Duck -- it's better in an amateur scope with a wide field of view. But the view of the center of this cluster was a splash of diamonds on the black velvet sky.
9. The Saturn Nebula (NGC 7009), a planetary nebula in Aquarius. I've seen the Saturn Nebula many times in my scope, but in the Hooker Telescope I could see a central bulge surrounded by a ring of gas. Very "Saturn-like." It was a highlight.
10. Neptune (now in Aquarius), was clearly seen as a disc -- its diameter is about 2.3 arc seconds, and we could see its largest moon, Triton.
11. M15, a globular cluster in Pegasus.
12. NGC 7331, an edge on spiral galaxy in Pegasus.
13. NGC 604, the largest known HII region in the Milky Way, embedded in M33, the Pinwheel Galaxy in Triangulum, glowed brightly. Our guides described NGC 604, a stellar birthplace and nursery for young hot stars, as the Orion Nebula on steroids.
14. M32, one of the Andromeda Galaxy's satellite galaxies, was brighter than I've ever seen it before.
15. The Blue Snowball Nebula (NGC 7662), a blue-green planetary nebula in Andromeda.
16. Our last stop was Uranus (now in Pisces), seen as a 3.7 arc minute disc. Its three brightest moons, Titania, Oberon & Ariel made a 20 arc minute triangle well separated from the planet. Some sharp eyed OCA observers also saw Umbriel, magnitude 15.
At the end of the evening, after 1 AM, a few of us stopped in at the control room of the Chara Array, where we chatted with array operator Dr. Chris Farrington. Chara is operated by Georgia State University, and combines the light of 6 one meter telescopes in an unusual interferometer configuration. It's the only science instrument still operating on Mount Wilson.
At 2 AM the last of us loaded our cars and started on the curving mountain roads from 5700 feet down to sea level. The lights of Los Angeles blazed away below us, and the skies above us were clear and bright with the starlight of late summer.
It was lovely on that mountaintop that September night, a mystical experience for me to walk in the footsteps of Hale and Hubble, to see that nearly 100 year old 100 inch telescope slewing quietly in the dark above us as we admired the view. Thanks for inviting me, Rich.