|NGC 6522 & NGC 6528: Globular Clusters (Sagittarius) RA: 18h 04.2m / DEC: -30° 01'.5|
Instrument: 10-inch Starfinder
Galaxy clusters are among my favorite deep-sky sights. However, a less common sight is two or more globular star clusters in the same field of view. NGC 6522 and NGC 6528 make a fine pair at 129X in my 10-inch. Their appearance is recorded in the sketch at left. The larger and brighter of the two is NGC 6522. This globular has a visual magnitude of 9.9 and features a stellar core embedded within a 5' diffuse glow. Across the field toward the northeast boundary, NGC 6528 appears as a 90" diameter patch of dull light. Surprisingly, NGC 6528 is slightly brighter at magnitude 9.6. I wonder if the outer shell is substantially fainter than the core region? This fine pair is squeezed between 3.0 magnitude Gamma Sagittarii and 4.7 magnitude HD 164975.
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Revised: January 26, 2003 [WDF]