19526

This article includes three images of the Arches cluster near the center of the Milky Way, each taken with a different telescope. I’d be interested to know what the three telescopes are.

John McKee
Brunswick, Maine

In the trio of progressively sharper (left to right) images, the leftmost one was taken in 1994 with a 3-meter telescope at the Lick Observatory in California, the middle image was taken in 1996 by the 10-m Keck 1 telescope atop Hawaii’s Mauna Kea, and the rightmost picture was taken in 1997 by the Hubble Space Telescope’s Near Infrared Camera and Multi-Object Spectrometer. —R. Cowen