30 years of Table Mountain Observatory and the Smithsonian Institute
Courtesy of James W Young
Why did the Smithsonian select Table Mountain as their Observatory? The historical facts bring the past to life but keep in mind history never ceases to be rewritten; here is a collection of pieces uncovering the development of Table Mountain Observatory by James W. Young, retired astronomer from JPL. Young worked at Table Mountain for 47 years. At his retirement he decided to complied facts about Table Mountain. His research, which is still in the making, required countless hours at the Smithsonian institute, hundreds of miles of traveling, as well as searching down family members of past TMO scientist to uncover historical facts. “Before we begin at the beginning, the following story may enlighten the reader to show what can come from ‘looking into the past’.” Young found the following series of events most intriguing and noteworthy, especially into how his own career parallels some of the following circumstances.
“Table Mountain?
I’ve heard of that. Isn’t that somewhere in South Africa?” Yes indeed, but not this one! There are a gazillion ‘Table Mountains’ around the globe, a term used to describe a flat top mountain just about anywhere. The most famous one is that found in Cape Town, South Africa, but there are many others much less known. Among those there are a number of such named mountains in the states of Washington and California, and in particular, this one in Southern California about which this history shall focus on.
Blue Ridge, with these two separate ridges approximately one mile apart. The two ridges are closest together three miles west of Wrightwood at a place named ‘Big Pines’ at an elevation of 6862 feet. California Highway 2 (the Angeles Crest Highway) runs east west through the Swarthout Valley, through Wrightwood, and cuts between the two ridges at Big Pines. This road continues west through the San Gabriel’s exiting the mountains some 60 miles east from La Canada/Flintridge communities near the Verdugo Mountains.
Table Mountain’s elevation is 7516 feet above sea level, with a secondary peak (named Mt. Peltier) having an elevation of 7473 feet, just over a mile to the east. Blue Ridge’s elevation ranges from around 7800 feet near Big Pines, to over 8500 feet (Wright Mountain) about four miles to the south-east of TM. At Big Pines, the ‘Table Mountain Road’ extends 1 ¼ miles to the top of Table Mountain from Highway 2. This road curves past the old Big Pines Ski Clubhouse, through McClellan Flat, then past the Table Mountain Campground entrance, and finally to the ski and toboggan play area parking lot. A small controlled access road extends further up to the east and ends at the Jet Propulsion Laboratory’s “Table Mountain Facility”.
Solar research by Smithsonian
The Smithsonian Institute’s interest in solar research began before 1900, but soon thereafter, Charles Greely Abbot became the driving force into the development of ‘field stations’ to conduct research far away from the environs of Washington, DC. Just exactly what the sun was sending into space in the form of all kinds of radiation was the interest. Was the sun stable in this outpouring of solar radiation in the various wavelengths then being studied? To make it plain and simple, this was called the solar constant, a measure of flux, or the amount of incoming solar electromagnetic radiation per unit area. The smallest variations due to pollutants and moisture is minimized by finding high elevation sites that is dry and far from pollution found in large cities. The haze, moisture, and other pollutants never permitted careful and statistical analysis of minute changes made from the sea level circumstances of Washington, DC.
Abbot established many worldwide field stations over the next two decades in Asia, Africa, South and North America. One attempt was to go all out by building a facility atop Mt. Whitney in California. In 1909, with donations and grant funds, a building was constructed on the very summit of Whitney, to house a full array of various instruments. Abbots primary purpose was to study the atmosphere of Mars from this site, as well as the earth’s atmosphere. The trouble was getting there, and even staying there. It was soon abandoned.
During the 1910s, Abbot was very involved with the newly established Mt. Wilson Observatory in Southern California. Again, they conducted solar research using several facilities at their disposal. Although Mt. Wilson was used during the early 1910s, other facilities that proved very effective were constructed in Chile, Egypt, and the southwest United States.
The mention of the ‘field station’ at Mt. Harquahala, Arizona is significant to the eventual development of the facility at Table Mountain. The site at Montezuma had been the SAO’s most useful and prolific data gathering station in the quest for pinning down an accurate number for the solar constant. But always looking for improvements in the calibration of data, a second station was needed to produce data of similar statistical accuracy for confirmation. Such a station was established at Mt. Harquahala, Arizona, about 90 miles to the west of Phoenix. The Montezuma station was doing extremely well, until a mining company began operations very near to the SAO facility. This created a pollution problem that showed up in their data, and from then on the Montezuma facility no longer could be used effectively. On top of that serious problem, the Harquahala station suffered severe problems due to the yearly summer monsoon activity that came from the Gulf of Mexico in the form of thunderstorms. Abbot and the SAO researchers were continually looking for some additional sites in the southwest United States. One was Clark Mountain, near the Nevada border with California (near where Interstate 15 is today). Abbot had been advised of Table Mountain, which was just a mile or so up from the newly developed ‘Big Pines-L.A. County Camp’. The Los Angeles County Board of Supervisors had purchased considerable acreage from local ranchers in the upper, or west side of Swarthout Valley. The old road through the valley had been re-graded through Lone Pine Canyon, making passage more tolerable up the steep grade from the Cajon Pass out of San Bernardino.
When Abbot was told about Table Mountain sometime in the late 1910s from someone at Mt. Wilson, (as mentioned earlier) he traveled to the area to see if this area could be a replacement site for the ineffective Mt. Harquahala, Arizona site suffering from weather related problems. The travel from Wilson to Table Mountain took approximately five hours! Once again, here is the picture taken during his initial visit with a few of his partners, unidentified.
By late 1924, Abbot decided to use Table Mountain for the new ‘field station’ to replace the one at Harquahala, Arizona. They took additional trips to the mountain to prepare for building the site to house the field director, his assistant, and various instruments. The photos show the developing Big Pines Camp, road, and the new cabin area at McClellan Flat a half mile up Table Mountain Road.
Establishing the Table Mountain Observatory (TMO)
Before making a final decision, tests of the sky clarity, moisture content, and other measurements were made during early spring of 1925. After concluding the site was perfect for their new field station, Smithsonian purchased part of the Big Pines-L.A. County Camp property, namely the summit of Table Mountain, from Los Angeles County. The LA County Board of Supervisors also helped with the road improvements from McClellan Flat to the top. Table Mountain was then surveyed for the building placements by additional trips of SAO personnel to the summit in the late spring of 1925.
The Smithsonian records do not actually indicate where all the wood was obtained for the buildings, but one could presume it came from local woodcutters, located in Saw Mill Canyon in the Swarthout Valley. Local wood had been used for many of the buildings at the Big Pines Camp, and certainly could have been used for the field station buildings on Table Mountain.
Now it was time to build the necessary facilities for the new field station at Table Mountain. In the summer of 1925, A. F. Moore of Smithsonian took charge of the construction of five separate buildings; two residences, a garage, a shop, and a tunnel ‘bunker’ for the instruments. As with all previous field stations, the site director and assistant were expected to live on the mountain, year-round. The road was plowed in the winter for access to the site, and the snowplow needed to be housed in a garage. A shop/office for computations use was also constructed. A water pumping facility with a storage tank was also necessary.
Sometime in the 1930s, after much difficulty with winter snows completely covering the access road on the summit’s north slope, a new route was chosen around to the south side of the final summit climb. By the late fall of 1925, Table Mountain had the necessary buildings, equipment, instrumentation, and staff to begin their full solar research programs for this newest field station. Equipment from Mt. Harquahala had been transported to Table Mountain, and Harquahala was phased out of the active Smithsonian stations.
Although not a part of Table Mountain, the ‘Big Pines - L. A. County Camp’ (also known as the ‘Big Pines Recreation Camp) was used in the 1920s and 30s by Smithsonian for supplies and the mail. In fact, this area actually became the town of Swarthout (later correctly spelled as Swarthout). The Recreation camp and Swarthout became a bustling business for skiers, toboggans, and even ice skaters in the winter, along with camping and outdoor recreational activities in the summer.
Most communications between the Table Mountain field station and Smithsonian in Washington DC were done by mail, but there needed to be a faster method of reporting data back ‘home’. Soon, negotiations were completed in 1926 for a telephone line to the recreations camp area; from the camp to Wrightwood, down Lone Pine Canyon to Keenbrook, and on into San Bernardino.
Communications between the field station and Washington DC soon became possible with this new line, at least from Swarthout. It wasn’t until 1935 that an actual line was made from the camp to Table Mountain itself.
The underground bunker, or tunnel enclosure, was designed after the successful use of them at Montezuma and Harquahala. Smithsonian continued is observatory work through the 60s.
Table Mountain taken over by the Jet Propulsion Laboratory
Jet Propulsion Laboratory took over the lease in 1962 changed the name to Table Mountain Facility (TNF) JPL conducts high-precision astrometric observation to support NASA and international spacecraft mission navigation, and confirmation and recovery of near-Earth objects such as comets and asteroids that may potentially impact the Earth. That’s another story.
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