Olszewski, E. W; Saha, A; Knezek, P; Subramaniam, A; de Boer, T; Seitzer, P
(American Astronomical Society, 2009-12)
Using imaging that shows 4 mag of main-sequence stars, we have discovered that the Galactic globular cluster NGC 1851 is surrounded by a halo that is visible from the tidal radius of 700 arcsec (41 pc) to more than 4500 ...