What does the San Fernando Observatory Do?

There are numerous ways to study the Sun, both with ground-based and space-based instruments. Ground-based observing is limited in the number of wavelengths that can be observed since the Earth’s atmosphere prevents many wavelengths from reaching the ground. Space-based instruments, however, are capable of capturing the whole electromagnetic spectrum or just parts of it, depending on the instrument’s design.

The San Fernando Observatory takes ground-based, full-disk, photometric images of the Sun in several different wavelengths and has been collecting these images since 1986, resulting in one of the longest photometric records currently available. SFO has also used the same two telescopes during that time, which means we don’t need to worry about calibrating and matching data from other instruments in order to create a uniform set of images. From these images, we identify the attributes of solar surface magnetic features such as sunspot areas and deficits (sunspots are cooler and darker than the Sun’s surface) and facular areas and excesses (faculae are hotter and brighter than the Sun’s surface). This information is used, along with solar irradiance measurements from satellite instruments, to investigate the observed variation in that irradiance, thus contributing to the further understanding of our Sun.