Mt. Laguna Comes of Age as an Astronomical Site

One of the three finest spots for star-viewing in the continental United States sits not on Palomar Mountain but here, 60 miles east of San Diego on the edge of the Anza-Borrego Desert, where four telescopes pierce an extraordinarily clear night sky.

The Laguna observatory, with the mirror in its largest scope measuring 40 inches in diameter, is overshadowed by the 200-inch giant on Palomar Mountain in North County, the world’s second-largest. (There is a slightly bigger but far less famous Soviet instrument.)

As an observation site, astronomers say, Laguna has attributes available almost nowhere else today in North American.

Those characteristics include: the largest number of clear nights anywhere in the continental United States; clean, non-turbulent dust-free air from the Pacific Ocean, and a location between a national forest and state park, limiting the light pollution that now plagues Palomar.

That location also results in the unusual mix of research and public relations done by astronomers from San Diego State University and the University of Illinois. Scientists from the two universities operate the facility jointly, specializing in the study of binary stars for clues as to how the universe ages.

They also reserve one of the four telescopes exclusively for visitors to the campgrounds in the Cleveland National Forest that surrounds the observatory. The 16-inch telescope, the first built on the mountain, was part of the agreement between San Diego State and the U.S. Forest Service that allowed the facility to begin in 1966.

In contrast to the cloistered nature of almost all other observatories, where the public seldom, if ever, is invited to participate, campers are allowed to hear lectures and look at nearby planets or stars every Friday and Saturday night during the summer.

“The Forest Service contract has us come out of the silver dome and talk to the public,” Burt Nelson, chairman of the SDSU astronomy department, said. “We’ve developed an excellent program.”

Both Nelson and Ed Olson, an astronomer from Illinois, said the public access program in no way detracts from the scientific research on Laguna.

“It generates a good public feeling and the response has been quite enthusiastic,” Olson said. “Indeed, it’s an important activity.”

As SDSU’s John Schopp put it, “There is a thrill 10 times greater for people to see Saturn with the naked eye through the telescope--to feel the photons coming across the void of space into eye--than to look at a close-up magazine picture taken by a satellite.”

The mix is planned to continue with an ambitious expansion--a visitors center and a 100-inch telescope--announced at a special Star Party on top of the mountain last week for selected SDSU alumni.

Construction on the visitors center is scheduled to be under way shortly, in time for the fly-by of Halley’s Comet between November and March. It will include a museum, an auditorium for more formal lectures, and living quarters to allow more astronomers from other universities to use the telescopes.

Seed money for fund-raising comes from $53,000 left to SDSU for public purposes by Auwona Harrington, the longtime observatory secretary who was killed last year by a drunk driver. Nelson said the center will be named for Harrington.

The new telescope, to cost an estimated $2.4 million, will allow astronomers to intensify their research of binary stars. Astronomers hope for completion within five years.

Nelson said the Laguna location is well-suited to look at eclipsing binary stars, which orbit each other at very close distances within a matter of days. As such, the astronomers never see light from both stars--they see only a single point of light--but that light source varies in intensity as the stars whip around each other.

“We get a lot of information about the physics of stars by tracing the light variations,” Schopp said. Binary stars are fairly common, Schopp said, since the formation process for stars usually involves a stellar cloud collapsing into two pieces as it shrinks in size, and the pieces continue to orbit each other as they pick up rotational momentum and more defined shapes as stars.

Nelson said the study of binary stars adds to theories about how stars and, therefore, the universe, age.

“With the size of our telescopes, it would be silly for us to look at distant things, the exotic stuff that can be probed at Palomar,” Nelson said. “But there are still a lot of basic questions still unanswered in our own backyard, so to speak.’

In some cases, the stellar blobs split into a star and planets instead of two stars, Schopp said, such as with our own solar system. “There must be many other sites, perhaps millions, where the same basic situation has attained, where planets and not a binary star form,” he said.

“My own guess is that planetary systems, even those with intelligent life, are quite common, sort of like riding a bus.”

Such musings, though not part of the normal research on the mountain, provide the philosophical underpinnings for astronomy. And because SDSU emphasizes teaching as much as research, the origins of the universe--the so-called Big Bang theory--are food for thought in undergraduate classes.

SDSU offers the only undergraduate and master’s degrees in astronomy available in the 19-member California State University system. With a steady number of 12 to 15 graduate students each year, the master’s program has graduated about 60 students in the last 20 years, Nelson said. About half go on to other universities that have doctorate programs, he said.

The graduate students offer the summertime lectures to campers as well as undertake long-term observation projects as part of larger research projects. Those who do not continue with doctoral studies either obtain jobs teaching in secondary schools or at junior colleges, or take astronomy-releated positions in private industry. Many combine computer modeling with astronomy.

“As a science, astronomy is undoubtedly the smallest of professions, in terms of the number of practitioners,” Schopp said. Yet astronomers are always scrambling to get sufficient time on telescopes around the world. Observatories from Mauna Kea mountain in Hawaii to the Canary Islands west of Portugal are always oversubscribed.

The push for a 100-inch telescope at Laguna results in part from the need for additional viewing time, especially since the Mt. Wilson observatory overlooking Los Angeles is no longer useful due to light pollution.

“It needs to be used in a unique way, since 100-inch facilities are still smaller than those at places like Palomar,” said Olson. “A new observatory on Laguna would allow us to run long-term programs (in nearby space) that require substantial observation time in order to gather sufficient data, things that can’t be researched by one or two random observations. They are the types of problems which tend to be interesting, but eclectic and therefore hard now to get viewing time for.”