William Herschel discovered NGC 6544 = H II-197 = h1994 on 22 May 1784 (sweep 223) and recorded "pB, pL, iR, r." John Herschel made the single observation "F; L; lE; bM; resolved." It was noted as probably a globular cluster in the 1921 Helwan Observatory lists, based on photographs taken in 1914-16.

200/250mm - 8" (8/23/84): at 200x, appears moderately bright with two stars are visible at the center and two or three stars are resolved at edges. The appearance is grainy with a brighter core.

8" (7/31/81): fairly faint, small, brighter core, easy but no resolution.

400/500mm - 17.5" (5/10/91): bright, 4'x3', elongated NW-SE, irregular and scraggly outline, mottled. Located in a rich star field. About six stars are superimposed including two or three mag 13 stars in a tight knot near the center. In addition, several faint stars are resolved at the edges (or nearby field stars). A double star with components mag 11.5/13.5 lies 2' SW.

600/800mm - 24" (7/30/16): at 260x; bright, moderately large, irregular scraggly halo, ~4'x3' roughly E-W. Well concentrated with a bright irregular core with resolved stars. A mag 11.2 is at the southwest side of the halo, 1.5' from center. Roughly 15-20 stars are resolved in the halo (horizontal branch magnitude ≈ 15.2), though some of these are likely field stars. At least a half-dozen stars are resolved in the central core including a pair of close brighter stars and a third nearly in line. At 375x at least a dozen stars were resolved over an irregular core region.

Notes by Steve Gottlieb