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Observing Sites

 
Over the years I've investigated many sites throughout the Southwestern United States, settling on a number of locations that offer either great seeing conditions, very darks skies with high transparency, or both. The dark sky sites listed below (Mount Wilson not included) require a drive ranging from 3 to 7 hours from my home in the Pasadena CA area. In late 2013 a group of stakeholders including myself sited a new telescope system at the Las Campanas Observatory in Chile. Full sky coverage of the southern hemisphere night skies is now possible thanks to this new facility.
**NEW** The Las Campanas Observatory, owned and operated by the Carnegie Institution of Washington DC, is located in the southern Atacama Desert of Chile approximately 100 kilometers (62 mi) northeast of the beach resort city of La Serena.  Sitting high atop a mountain ridge between the Pacific Ocean and the Andes Range, Las Campanas enjoys the clear, dry conditions critical for astronomical observations.  The Pan-American Highway threads its way north-south along the desert floor far below and about 12 air miles west of the Observatory. From the Pan-American Highway (Chile Ruta 5) to the Observatory is a 21.5 mile drive on a combination of paved and excellent dirt roads.

Pictured here is the roll-off shed on Las Campanas’ Manquis Ridge at 7600 feet elevation.  The roll-off houses a custom made Astro-Physics 12” Mak-Cass telescope installed in December 2013. The facility consists of two spaces, a 28 ft. long x 11 ft. wide telescope floor and a 10’8” long x 11 ft. wide separate control room on the far south (right) end of the building.   At upper left (on the background peak) are the twin Magellan 6.5 meter telescope domes. Directly behind the roll-off can be seen the dome of the Henrietta Swope 40” telescope.

Mount Wilson
The Mount Wilson Observatory is known to be one of the finest sites on the North American continent for exquisite seeing conditions. Perched on the Front Range of the San Gabriel Mountains at an elevation of 5700 feet, this Observatory is situated well above the normal inversion layer of the Los Angeles Basin and benefits from the prevailing laminar airflow off the Pacific Ocean. Seeing conditions of 1 arc-second are common with 0.5 arc-second or better nights not at all unusual. The darkness of the sky varies with the season and local conditions, with limiting magnitude ranging from 4.5 to 6.6 depending upon the presence of the marine layer.

Pictured is the 16" dome covered in a mantle of snow. The primary instrument in this dome is a Meade 16"LX200 telescope. Having a choice of this telescope or setting up my own equipment in the dome, I can tailor my imaging effort to best accomplish the goals set for any session.
Little Blair Valley Anza Borrego Desert State Park is the site of a monthly star party of friends and acquaintenances. This site is located in Eastern San Diego County in Anza Borrego Desert State Park and sits at an elevation of 2700 feet in a predominantly creosote-ocotillo vegetation zone. The weather conditions are extreme to say the least, with temperature swings of seventy degrees Fahrenheit possible over the course of a 24 hour period. Daytime summer temperatures over 100°F and nighttime winter lows in the teens are not uncommon. The skies can remain exceptionally clear, even when nearby mountain areas are clouded over, giving rise to the local legend of supernatural intervention, or a God's Eye over this area. Overall, I'd rate the average seeing of this site at about 2 to 2.5 arc-seconds, with an average limiting magnitude of about 6.6. The lights from El Centro, CA do result in a moderate light dome to the SE while the lights of San Diego can do the same to the SW, depending on the influence of the marine layer. The photo to the left shows two of my observing buddies, Dave Held and Dave Davis just finishing set up and waiting for nightfall.
Oak Springs Summit
Oak Springs Summit is located at an elevation of 6200 feet in the Delamar Mountains of southeastern Nevada. Because of it's proximity to the top secret Area 51 base, commercial overflights are almost non-existent, making this a great site for wide field astrophotography. Very good seeing coupled with inky black skies make this one of the best sites I have visited in the Southwest. I've found the seeing to be consistently good at this site during the many times I visited there in the months of August through October. Evaluating the seeing by splitting close binary stars with precisely known orbital elements, I've managed to cleanly resolve separations down to 0.36 arc-seconds with my C-14. That speaks volumes about the incredibly stable air over this site! Las Vegas puts up a very meager light dome about 10° up into the SW sky, mostly shielded by the surrounding mountains. In every other direction the sky is pitch black. As one would expect, this part of Nevada shows up like a "black hole" on familiar IDAS night map of the United States. Being that close to Area 51 and the Extraterrestrial Highway, maybe I'll get abducted by alien beings some night while imaging their distant home galaxy!
Red Cloud Road Red Cloud Road Site is located at 1800 feet elevation in the desert of Eastern Riverside County approximately 9 miles west of Desert Center, CA and 3 miles south of US Interstate 10. It's a wide open, flat landscape with unobstructed horizons to the north and south, sporting plenty of great places to set up. Similar to Little Blair Valley, it's distinguished by a creosote-ocotillo vegetation zone. Access to the site is via a good dirt road easily negotiable by a family sedan. This dark sky site has an average seeing of about 2 arc-seconds and a typical limiting magnitude of between 6.6 and 6.8. The most obvious light dome visible from this site is to the south, created by the lights of El Centro, CA. Fortunately it's not very obtrusive owing to the distance between the site and El Centro itself. Air traffic arriving and departing the Los Angeles area can be somewhat of a nuisance when attempting wide field imaging at this site, particularly in the northern and eastern skies. A bit too hot to visit during the summer months, the Red Cloud Road site is perfect in the spring, late fall and winter.
Figueroa Mountain Lookout Figueroa Mountain Lookout is located in the Santa Barbara Mountains overlooking the Santa Inez Valley to the southwest. A dirt road winds its way to the 4500 foot summit, which has been graded flat into a large gravel parking lot. Sunset views from Figueroa Mountain can be quite beautiful, with the day star sinking into the ubiquitous fog of the Pacific Ocean to the west. Because of it's proximity to the ocean, this site can have very good seeing, on the order of 1 arc-second or better. In addition, surrounding light pollution is minimal, making this a dark sky site with a limiting magnitude of about 6.8. The one drawback however, is it's location directly beneath the normal flight pattern between Southern California and the Bay Area. Wide field imaging can be a test of patience at this site, with plenty of exposures ruined by the tracks of aircraft strobe and navigation lights. The site is better suited to longer focal length instruments and correspondingly smaller field of view images. Prevailing winds are from the north, so setting up on the south side of the parking lot (as pictured here) is important.
Grandview Campground is located at an elevation of 8600 feet in the White Mountains of eastern Inyo County. The Massive White Mountains rise to a height of over 14,000 feet and form a barrier between the Owens Valley on the west and the arid Nevada desert on the east. This is the home of the famous Bristlecone pine, reputed to be the oldest living things on the planet. Sky conditions are very dark with no real noticeable light pollution in any direction. Seeing can vary, but I can truthfully say I've had very good conditions during my visits to this site. Grandview Campground, accessible by any factory standard vehicle, is an established US Forest Service Campground with primitive facilities (pit toilets, no water) in a scrub and Juniper pine zone. Because of its high elevation, this is a summer and fall site only, with severe cold and potentially heavy snows blanketing the ground during winter months. A usual weather pattern in the Whites and their nearby western neighbors, the Sierra Nevada, is for cumulus buildups during the afternoon during the summer months, sometimes culminating in a thunderstorm but usually always dissipating in the early evening. For that reason I prefer this site in September and October, when the moist air flows eastward from the Pacific Ocean abate and clear skies and dry conditions are the norm.
The Laguna Mountains are located in eastern San Diego County, California and form a barrier between the cooler coastal plains to the west and the austere grandeur of the Anza Borrego Desert to the east. At an average elevation of around 6000 feet across the roof of this range, the Lagunas are a delightful sky-island environment of mixed oak and pine vegitation. A gently rolling terrain builds up from the Pacific Ocean to culminate at the crest of this mountain range, where an abrupt and scenically breathtaking escarpment plummets thousands of feet to the arid eastern desert. This topography results in a relatively laminer airflow over the range, bringing with it exquisite seeing conditions over much of the year. I've noted seeing of <0.5 arc-seconds here on the very best of nights, with 1 arc-second seeing a fairly common occurance. In my experience, the only other place in California that can consistently match or beat the Lagunas for seeing is the Mount Wilson Observatory. When a heavy marine layer blankets the coastal plains to the west and snuff out the lights of San Diego, this site delivers naked eye limiting magnitude skies of 6.8 or better. head

The Aztec Hills site is located just south of Arizona Interstate 8 near the settlement of Dateland in Yuma County. This is strictly a winter site with generally warm, sunny days and cool evenings. Snowbird retirees from all over the United States migrate to this southwest corner of Arizona every winter to escape the harsh climate of their homes. During the summer temperatures frequently top 110°F here and the place is essentially deserted except for a few local inhabitants. Winter night views show a clear cut outline of the Milky Way's Orion Arm with a limiting magnitude of around 6.6 to 6.8 on the best nights. The area south of this site includes the off limit portions of the Barry M. Goldwater Bombing Range, where the roar of fighter jets can be heard all hours of the day as they practice over this harsh landscape. Occasionally the aircraft will drop slow falling incendiary flares during night maneuvers, lighting up portions of the southern sky and putting a real damper on imaging. Fortunately that seems to be an early evening practice, with the later evening remaining still and dark. The site is conveniently within about 3 miles of Dateland, where fuel and some basic food supplies can be found.

The East Mojave National Preserve is a 1.6 million acres desert park established in 1994 as part of the California Desert Protection Act and encompasses much of the Mohave Desert as well as transitional elements of the Great Basin and Sonoran deserts. Elevations vary from about 800 feet near Baker, California to 7,929 feet atop Clark Mountain near the Nevada state line, with diverse terrains ranging from sand dunes to pinyon-juniper forests. This large swath of land is essentially bounded on the north by Interstate 15, on the south by Interstate 40, and on the east by the California-Nevada border. Summer temperatures here often exceed 100°F while winter nights can dip down into the teens. Depending on your location in the Preserve, at night you'll experience varying degrees of a light dome from Las Vegas, Nevada to the north or northeast. Generally speaking, all locations in the night sky except those towards Las Vegas are very dark and will provide astronomers with a genuine dark-sky experience. The Preserve does not get the amount of traffic common to typical National Parks, so there are plenty of places to find set up where visitors are few and far between.
\ The Kofa Mountains of Western Arizona are a spectacularly scenic region of the Sonoran Desert offering dark skies for astro-imaging. There is a small but relatively unobtrusive light dome at night from Phoenix, about 130 miles to the east as well as another from closer Yuma, Arizona to the south. Neither of these cities have any impact on deep sky imaging from this site however, making this a prime location for Arizona and California amateurs alike. The Milky Way is very prominent on clear nights, cut sharply into the night sky with a great amount of detail visible to the naked eye. The nearby town of Quartzsite, Arizona is a convenient place to stock up on supplies, food and gasoline. Being a desert location, the best season for visiting this site is from October through April, when daytime temperatures are moderate and evenings can bring chilly conditions. The summers are blistering hot and will be avoided by all but the hardiest of Sun worshipers. Access on many of the dirt roads into the Kofa National Wildlife Refuge, where this site is located, is best accomplished with a 4WD vehicle, although well graded roads can also be found that are trailer accessible.