Angeles National Forest

Table Mountain Observatory

Table Mountain Observatory

Table Mountain Observatory, usually called TMO, is the astronomical part of NASA JPL’s Table Mountain Facility above Wrightwood in the San Gabriel Mountains. The facility overlooks the Mojave Desert about 60 miles northeast of JPL’s Pasadena campus, at roughly 7,500 feet in elevation. Its altitude, mountain setting, and distance from Los Angeles air pollution make it well suited to observing and atmospheric research. [1]

The scientific history of the site reaches back to 1926, when the Smithsonian Institution established an observatory there for solar irradiance studies. JPL began using the mountain for spacecraft solar-panel testing in the late 1950s and early 1960s. In 1962, JPL acquired the U.S. Forest Service lease, built TM-1, installed a 16-inch optical telescope, and achieved first light on August 1. [2]

Table Mountain Facility has never been only an astronomy site. Its work has included solar testing, spacecraft calibration, atmospheric lidar, ozone and water-vapor measurement, and instrument-comparison campaigns. Long-term lidar research has measured stratospheric ozone, temperature, aerosols, tropospheric ozone, and water vapor. [1][3][4]

A major modern instrument is Pomona College’s 1-meter, 40-inch telescope, shared with JPL. The telescope has a 40.5-inch mirror and supports CCD imaging, filter wheels, polarimetry, near-infrared work, and adaptive optics. Built between 1982 and 1985, and improved with new optics in 1996, it has served both student observing and research. [5]

Table Mountain Observatory is a mountain-edge science station where the San Gabriels meet the desert sky. It belongs to the same regional landscape as Cajon Pass, Big Pines, Angeles Crest, Wrightwood, and the Mojave overlook country, though its purpose is scientific rather than recreational.

Sources and Further Reading

[1] NASA Jet Propulsion Laboratory, Atmospheric Lidar Group. Table Mountain – TMF

[2] NASA Jet Propulsion Laboratory. Table Mountain Facility: 1961-1962

[3] NASA Jet Propulsion Laboratory, Atmospheric Lidar Group. JPL Table Mountain Atmospheric Lidar Group

[4] Network for the Detection of Atmospheric Composition Change. Table Mountain Facility, California

[5] Pomona College. Table Mountain Observatory

Dawson Saddle Trail

Hike the Dawson Saddle Trail for Cooler Temps

AUGUST 19, 2020 BY CHRIS KASTEN

Late afternoon sun works its’ way through layers of smoke and cumulus clouds while the Ranch Fire burns way down below in the mouth of San Gabriel Canyon. That’s Mt. Williamson in the background, just right of center.

Hike the Dawson Saddle Trail for cooler temps and beautiful views of canyons and desert. A few days ago, Joanie and I drove up to Dawson Saddle for a late afternoon hike. Located approximately 13 miles west of Wrightwood, Dawson Saddle is the highest spot along the Angeles Crest Highway. At an elevation of 7,901′ , this trailhead starts you out at about the coolest temps possible this time of year. While the Front Country of the San Gabriel mountains smolders during the occasional heat waves of summer, high country hikes, or walks, are well worth considering for a refreshing getaway.

Scarlet monkey flowers are in full bloom along this small unnamed stream flowing off of Mt. Burnham. The location of the photo was taken along Highway 2 (Angeles Crest Highway) just east of Dawson Saddle. In the background is a culvert running underneath and through the old rock work of the highway.

About a mile up the trail, while heading toward Throop Peak, we caught this scene of smoke and cumulus clouds out over San Gabriel Canyon. The Ranch Fire II was still out of control a short distance up Highway 39 near Azusa. Up above 8,000′ , the breeze coming in from the Pacific was cooling, yet tinged with the acrid scent of burning chaparral from miles away. Our light was beginning to fade and we turned back around for the trailhead. While driving back home, we stopped at a spot alongside the highway, where an unnamed stream flowed down the north slope of Mt. Burnham and then under the road. Clusters of Crimson Monkey Flower and Columbine graced the stream bed. Scooping up the icy water and splashing our faces and arms under a darkening summer sky revived us for the twilight drive back.