Subaru Telescope captures visible-light images of comets ISON and Lovejoy

During the early morning of October 31, 2013, the Faint Object Camera and Spectrograph (FOCAS), mounted on the Subaru Telescope, captured images of the detailed structures of the envelopes of dust and gas — the comae — surrounding the nuclei of comets ISON (C/2012 S1) and Lovejoy (C/2013 R1).

The optical image of Comet ISON follows Subaru’s successful mid-infrared imaging of it with the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on October 19 and 21. The current image, taken with an exposure time of five seconds, shows the structure of the coma — the atmosphere around the nucleus — as well as a tail extending from the nucleus. Named for the robotic telescope that spotted it, the International Scientific Optical Network (ISON), the comet was 118 million miles (190 million kilometers) away from Earth and 93 million miles (150 million km) from the Sun at the time of observation conducted by Masafumi Yagi from the National Astronomical Observatory of Japan. As it continues to head for its close encounter with the Sun, Comet ISON is expected to become very bright.

During the same night of Yagi’s observations — October 31, 2013 — FOCAS also captured an image showing the detailed features around the nucleus of Comet Lovejoy, which was only recently discovered in September 2013 by the Australian observer Terry Lovejoy. The most notable aspect of this image is the X-shaped complex structure surrounding the nucleus, which is probably a dust jet flowing from it. It can be seen around midnight from Japan and Hawaii.

“The observation of the night was hard because the weather conditions changed often,” said Yagi. “We needed to open and close the dome several times. We were fortunate to capture clear images of the comets and share these images with so many people.”