Observatory Site

07/02/06

LOCATION

The Francisquito Observatory is located approximately 50km north of downtown Los Angeles, California, and approximately 50km inland of the Pacific Ocean in a straight line from the well known tourist centre of Santa Monica. Please see the FAQ page for information on the origin of the name "Francisquito" and clues on how to pronounce it.

Like most of Southern California, the Francisquito Observatory enjoys long stretches of sunny days and clear nights. This is the single most advantageous aspect of the observatory's location. Nearly all rainfall (averaging only 35cm per year) is received in the five-month period from November through March. The Santa Clara River valley runs directly west from the observatory site to the coast and usually provides a conduit for dry, stable air to move inland; as a result, atmospheric conditions are usually quite steady and provide for good telescope 'seeing'. During May and June, moist air will sometimes push far inland from the coastline and cause hazy conditions and heavy fog during the late evening/early morning hours.

On the negative side, being situated in a vast metropolitan area with over 15 million inhabitants means that light pollution of the night sky is a significant issue for observatory operations. The observatory's location was chosen not for its favorability as a telescope site, but rather, for its pleasant and convenient situation for day-to-day living. Surprisingly, the observatory site itself has a visual limiting magnitude of about 3.5 to 4.0 on most moonless nights. This is due to the fact that the Angeles National Forest adjoins the observatory site to the North and East, and thus limits the extent of urban development in the immediate area. If one travels just 2km from the observatory site toward the south, the visual limiting magnitude drops precipitously to -1.0 or worse.

SITE-SPECIFIC OPERATING RESTRICTIONS

The observatory features an outdoor telescope installation, with the instruments situated in one corner of a small garden. Because the observatory is located in a typical, tightly-packed Southern California housing development, the amount of sky available for observing is severely restricted. The eastern sky is mostly clear above an altitude of 15 degrees. The southern sky is blocked to an altitude of 55 degrees and the western sky is blocked to an altitude of 75 degrees, making observing west of the local meridian infeasible. The northern sky is mostly open, except that there is a powerful sodium vapor street lamp located only 10 metres from the telescope; this is referred to with great disdain as the STREET LAMP FROM HELL.

One would think with all these restrictions and negative factors, that getting any kind of useful astronomy done is impossible. Well, here is the defining characteristic of the Francisquito Observatory: we strive to make the most of what we do have - abundant good weather, a steady and surprisingly dark sky directly overhead, and an unobstructed eastern sky. In spite of so many things working against us, with careful planning it is possible to work around the restrictions and achieve good results. Accordingly, NEA targets are generally restricted to those at declinations between 0 degrees and +50 degrees; if an NEA is a real fast mover, we can sometimes sneak down to -5 degrees declination for a few minutes just east of the local meridian. Virtually all astrometric observations are made within the two-hour window directly east of zenith.

OBSERVATORY GROUNDS

The garden setting makes the Francisquito Observatory (arguably) one of the fairest places in our galaxy to work as an astronomer. There are brightly colored flowers blooming year round and the experience is made all the more pleasant in spring and early summer by the fragrant perfume of orange blossoms and jasmine. A small pond with a splashing waterfall and swirling constellation of koi fish make working here a pleasing experience for the ears as well. After scanning dozens of CCD images each night showing nothing but dark space interspersed with the occasional orbiting rock, glowing clouds of ionized gas, and the violent thermonuclear furnaces of distant stars and galaxies, it is a supreme pleasure to sit in the observatory garden and be surrounded by such an abundance of life.

Click on any of the thumbnail images below to see the full-size image.