There are a couple hundred globular clusters known to exist in the Milky Way. Almost all of them are residents of the summer sky; not far away from the bulge of the galactic center in Sagittarius. A few notable ones can be seen in the spring and fall as well, and the outlier M79 culminates in the middle of winter. Charles Messier catalogued an appreciable number of globulars in Sagittarius and Ophiuchus, but missed many more. One summer night when I had nothing better to do, I decided to use Lewis and Clark's ATI CAT (Computer Aided Telescope) system to track down some of these overlooked globulars. The CAT (here mounted on a Celestron C8) was an early version of digital setting circles, very expensive and difficult to align. It works, however, and I find it fun to browse through a section of the NGC every once in a while, letting the computer pick my targets.

I started my original tour at 6:22 UT on June 30, 1994 and ended at 8:36 UT on the same date. In the two hours the routine was running, I saw 40 of the globulars the CAT guided me to and only failed to see one. I encourage all to take a variation of this tour, using any optical aid available.

Many of the globulars were competing with skyglow and haze, just above the southern horizon. The naked eye limit here was probably close to 4.5. Under dark skies, most of these objects will look much better through an 8" telescope than my descriptions indicate. The brightness of the sky background called for medium power (113x) on most of the objects to provide contrast. Brighter objects received higher power (160x) if an attempt at resolution was made. Lower powers seemed useless.

I set the CAT to allow only certain objects in the tour. First, of course, I limited the objects to globular clusters. Then, to account for the horizon, I eliminated objects that were at altitudes of less than 10 degrees. I set the magnitude parameters to include objects from magnitude 7.5 to magnitude 11.0, removing the brightest globulars as well as those that I didn't have much hope of seeing. And so I proceeded.

The Objects
Coordinates for Milky Way globulars can be found in the online Astronomical Almanac. Many of these globulars also are listed in my Globular Cluster Database in Skytour.
(An object number with nothing in front of it indicates NGC catalog)

Obj. Mag. Diam.
63048.4 6.8' Diffuse but easy; fair-sized in a sparse field. Thought I resolved a few stars near edges.
6316 9.0 4.9' Faint; totally unresolved. Easy because it is 2' away from a magnitude 9.5 field star.
6293 8.2 7.9' Unresolved but bright. Compressed near center. Field quite rich.
6355 9.6 5.0' Extremely diffuse; near limit of perception. Mid-sized; no central condensation. Lies 10' W of a trapezoidal grouping of faint stars.
6144 9.1 9.3' Suspected, but not positive. Appears to be a relatively large cloud near a star of magnitude 10.
6284 9.0 5.6' Refreshingly bright. Very compressed. No resolution, but might be partially resolved with 11" aperture.
6325 10.7 4.3' A real challenge for averted and extended (keep eye motionless for 30+ seconds) vision. It is 8' south of the western edge of a keystone-shaped asterism of 10th magnitude stars. Quite small; probably visible only because its center is condensed.
6287 9.2 5.1' Much easier than 6325--large, diffuse, and unresolved. In the midst of a star-poor field.
6235 10.2 5.0' Easy with averted vision. In the middle of a triangle of faint stars. Not extremely compressed. Nice field.
6342 9.9 3.0' Small and compressed; high surface brightness. Held without averted vision. 11th magnitude star nearby, as well as peculiar star patterns in surrounding field.
M9 7.9 9.3' Large and unmistakable. Partially resolved around the edges, with an irregular outline.
6356 8.4 7.2' Very high surface brightness. Beautiful at 160x, though still unresolved. Edges appeared ragged and nucleus off-center.
M107 8.1 10' Large and diffuse (often listed as magnitude 9 or fainter) but with enough total brightness to make it stand out. In middle of obtuse triangle of 9th magnitude stars. Fascinating though faint at 160x. Surface appeared uneven.
6366 10.0 8.3' After much effort, I gave up. My only failure in the routine.
6229 9.4 4.5' Worth the jump up to Hercules. High surface brightness; makes an equilateral triangle with two 7th magnitude stars. No resolution, even at 160x.
6535 10.6 3.5' Not distinct; fairly diffuse for its size and best with averted vision. In field of faint stars.
M14 7.6 11' Very bright and large, with only slight condensation over a large central area. Grainy at 160x, but only a few field stars seen near edges.
6539 9.6 6.9' Right at the limit: a very slight brightening near an 11th magnitude star. Rest of field is star-poor.
6517 10.3 4.3' A tiny but distinct glow: vertex of a right angle between two stars of 9th and 10th magnitudes.
6440 9.7 5.4' Substantially larger and brighter than 6517; held without averted vision. In line with three 11th magnitude stars.
6642 8.8 4.5' Quite compressed and fairly bright, but featureless. Shares field with red star of 7th magnitude.
6401 9.5 5.6' Small and very diffuse. Right on top of an 11th magnitude star, which makes it look more like a planetary nebula than a globular.
6544 8.3 8.9' Very pretty. Rich field; 11th magnitude star combines with nuclear area to give impression of E-W elongation. Bluish in color like M13. Irregular outline but no resolution at 160x.
6638 9.2 5.0' Nice; fairly compressed. Perfectly round. Bright at 160x, but no resolution.
6553 8.3 8.1' Large, faint, and diffuse, like a miniature M55. No central condensation, but a star of magnitude 11 sits on the northern edge.
6522 8.6 5.6' Easily seen. Faint stars nearby. Moderate compression; round.
6528 9.5 3.7' Tiny, diffuse glow. Held without averted vision; round with no detail.
6624 8.3 5.9' Bright; large central area and nearly stellar nucleus. Faint field stars near edges.
6569 8.7 5.8' Dimmed by its low altitude, and devoid of detail. Large and diffuse, but easy.
M69 7.7 7.1' Large but low. Compressed. A magnitude 7.5 star is two diameters away.
6652 8.9 3.5' Almost too low; small and round. Has a 7th magnitude star in the field.
M70 8.1 7.8' Mid-sized and bright. Stellar nucleus appears off-center. Little detail visible.
M54 7.7 9.1' Appears very small in relation to size given by CAT. Too compressed to be resolved, but it is bright and 160x gives a good view of the nucleus.
M75 8.6 6.0' Much like M54, but even smaller and more compressed. Edges appear uneven, with extensions.
6712 8.2 7.2' Decidedly uncompressed. Ghost-like, with some resolution at 160x, especially along a central axis like that of M4.
6760 9.1 6.6' Large, diffuse, unresolved. Not compressed at all. Easily detected, though.
M71 8.3 7.2' Complete resolution even at 113x. Remarkable brightness and color variations in individual stars. Bright star near center. Not compressed; looks more like M11 than a globular.
M56 8.3 9.1' Not extremely compressed, but substantial compared to M71. Lots of resolution at edges and across face with 160x. Sits in a pretty Milky Way field.
7006 10.6 2.8' Small, round, and featureless, but bright. Moderately compressed as a whole.
6934 8.9 5.9' Bright; resembles 6229. Stellar nucleus and slight resolution around edges at 160x. Star one diameter to the NW is reddish.
M72 9.4 5.9' Diffuse and featureless, with a low surface brightness. Doesn't hold up to 160x, though well-seen at 113x.