Pushing the Boundaries of Ground-based Observing

If you go out very late tonight or early in the morning, look around for the constellation Cassiopeia. It’s a W-shaped star pattern high in the northern part of the sky. Not far away from it, you might spot a little schmear of light that looks like a little oval-shaped cloud. This is the Andromeda Galaxy, which is the closest spiral galaxy to our own Milky Way. It lies about 2.5 million light-years away, so the light that you see coming from it as you view left the galaxy about the time some of our earliest ancestors were living in caves.

If you look at Andromeda (M31 for short) through a decent back-yard type telescope, you can make out a spiral galaxy, but it’s a pretty fuzzy view. And, if you could zoom the view using a professional observatory to see individual features, it would be focused on only a part of the galaxy since such a telescope would like magnify the view so much to get the features you want. As far away as M31 is, it can quickly fill a field of view as you zoom in. So, astronomers have been seeking new and better ways to image it completely and sharply from the ground, and use more sophisticated data analysis techniques to bring out individual features in M31 (and any distant object, really) while still capturing the entire scene. They want the beauty of a panoramic scene with the clarity of a close-up.

The Subaru Telescope of the National Observatory of Japan recently took a full view of the Andromeda Galaxy using the telescope’s powerful Hyper Suprime-Cam (HSC) to try and get that high-resolution panoramic view. The data were processed through special software by scientists affiliated with Subaru, the Kavli Institute for Physics and Mathematics of the Universe, and Princeton University. The result is a spectacularly sharp view of our distant neighbor in space. If you zoom in on the full-resolution image, you can see individual stars in the galaxy, which is just amazing.

The amount of data needed to create an image of this size and clarity is quite large, and requires what’s called “pipeline” processing. As more of these high-resolution data sets stream from the world’s telescopes, such pipelines will grow and evolve. This “first light” image from the HSC-equipped Subaru Telescope shows the power of good equipment and high-end processing to bring dim, distant objects in the universe “closer” to us for study. The fact that this comes from a ground-based telescope on the summit of Mauna Kea in Hawai’i, which is well above much of Earth’s atmosphere (but still has to deal with some atmospheric interference) is really astounding.

Take some time to browse the larger image and check out some of the other images that the Subaru folk posted on their page. Let your eyes zoom to Andromeda through Subaru’s high-resolution camera, and let your imagination explore this distant stellar city.